Free Essays

Biology Assignment, Types of Wounds and Quick Treatments

5 Types of Open Wounds: Abrasion – Abrasions are wounds caused by traumatic scraping and loss of skin. Falls occurring while in motion frequently lead to skin abrasions. Extensive skin loss may occur with high-speed motorcycle or similar accidents. Thorough cleansing and bandaging of abrasions involving small/limited skin loss should be done as first aid. Extensive or deep abrasions require a bigger treatment, which, in the most severe cases, may include skin grafting (used to permanently replace damaged or missing skin or to provide a temporary wound covering). Lacerations – Lacerations consist of cuts to the skin caused by sharp objects.

Broken glass, knives, and other sharp tools are what commonly cause/started skin lacerations. In “Common Simple Emergencies,” thorough cleansing of a laceration wound is important in preventing wound infection. Adhesive strips, tissue adhesive, skin staples or stitches can be used to close a laceration wound. How to close a laceration wounds depends on the location, shape, size and the severity of the wound. Punctures – Puncture wounds result from forceful, deep skin penetration by slender objects. Accidentally stepping on a nail or other sharp object is a common cause of puncture wounds.

Punctures wounds provided bacteria with an entryway into the deep layers of the skin where they can grow. The risk for tetanus, an infection caused by the bacterium Clostridium tentani, in simpler words meaning, infection from dirty metallic objects may provide health concern. Puncture wounds can be treated through cleansing and making sure you are up to date with your tetanus vaccination. Puncture wounds associated with animal, such as bees or most commonly dogs and human bites may require some medicine/antibiotic treatment because of the high risk infection to the bone and flesh.

Animal bites may require rabies vaccination if the animal has rabies, or if their current status is unknown. Incision – Rarely occurs, unless when handling knives, or bumping into something sharp, incision is almost like a scratch except deeper and more serious. More like a cut in the skin caused by a sharp object such as a knife, broken glass, scissors or surgeon’s scalpel. Incision wounds are also “neat” (does not affect a large amount of area with little wounds) and the edges of the skin are usually smooth (not damaged, more like split)

Avulsion – An injury in which a body structure is forcibly detached. It most commonly refers to a surface trauma where all layers of the skin have been torn away; exposing the underlying structures (e. g. subcutaneous tissue, muscle, tendons). This is similar to an abrasion but more severe, as body parts such as an eyelid or an ear can be partially or fully detached from the body. (Simple form: the forced removal of all of layers of the skin, the Epidermis, Dermis and Hypodermis, revealing tissues, muscles, tendons and sometimes bones underneath)

Free Essays

Biology Paper on Evolution of Birds

Scott Lewis Evolution Lab BIO/101 University of Phoenix Evolution Lab The evolution lab report is based the theory of Darwin and Wallace and determining the type of seeds the birds feed on an average rainfall in the island of Galapagos. The birds in this experiment live on the island and survival is not easy and it is baking hot during the day, freezing cold at night and there isn’t much food available. Because of this, the birds have very specialized feeding behaviors. An example of evolution resulting from natural selection was discovered among birds living in the Galapagos Island.

These birds have varieties that vary in what they eat and their appearance. The specialization developed allowed the birds to survive during the dry season or times of drought/low precipitation when little food is available. Then this specialized tool allows the birds to better compete for food resources with other birds and animals. The objective of this experiment is to differentiate and determine what happen when the parameters are changed over time between the Darwin and Wallace report. The first experiment is meant to study the influence of beak size on the birds’ population numbers.

Deep breaks are suited to crack hard seeds, and shallow beaks are better suited for cracking soft seeds. To test out the hypothesis, I was able to change the beak size of Darwin to 17. 0mm and let Wallace Island at 12. 0mm. By doing so, the average beak size rose over time whereas it fluctuates for Wallace. The clutch size was changed from 10 eggs to 30 eggs for Darwin and left at 10 eggs for Wallace as well as population of 600 and 200 respectively. I also wondered about the changes of bird beaks from island to island.

When I changed the cm on the beak, I was able to conclude that these numbers help them adapt to the island and make them more fit to survival on available food. The material that was used to create this hypothesis was accessed through the Evolution Lab on the student website. I was able to change the clutch size as well as the beak because I felt that those where the most important aspects of these experiment. The determine reason for this according to the Darwin and Wallace, is the difference in temperature between summer and winter and the associated consequences for the life of the birds.

The different approach that I used for the clutch size was related to biological characteristics, such as the body weight or environmental factors such as climate. I was able to input the two sizes into the data to come up with the results as far as how the population grows with each size. ================ Input Parameters ================ Parameter DARWIN WALLACE ——————————————- Initial Beak Size: 17. 0 mm 12. 0 mm Heritability: 0. 7 0. 7 Variance: 2. 0 2. 0 Clutch Size: 30. 0 eggs 10. 0 eggs

Precipitation: 27. 0 cm 27. 0 cm Population: 600. 0 birds 200. 0 birds Island Size: 1. 0 km 1. 0 km ==================== Experimental Results ==================== Year Dar Beak Dar Pop | Wal Beak Wal Pop ————————-+——————- 1997 17. 08 600 | 12. 05 200 1998 17. 08 2142 | 12. 11 273 1999 17. 2 833 | 12. 16 401 2000 17. 35 2127 | 12. 27 447 2001 17. 46 866 | 12. 37 610 2002 17. 69 1875 | 12. 47 651 2003 17. 89 1096 | 12. 7 650 2004 18. 0 1924 | 12. 49 746 2005 18. 08 1149 | 12. 65 791 2006 18. 11 1727 | 12. 84 803 2007 18. 2 1280 | 13. 02 788 2008 18. 27 1885 | 13. 25 742 2009 18. 43 1100 | 13. 32 774 2010 18. 64 1999 | 13. 33 726 2011 18. 72 1097 | 13. 48 734 2012 18. 72 1974 | 13. 63 767 2013 18. 85 1063 | 13. 59 883 2014 18. 95 1960 | 13. 69 872 2015 18. 98 1225 | 13. 82 816 2016 19. 1 2039 | 13. 96 806 017 19. 16 1035 | 14. 11 815 2018 19. 27 2030 | 14. 16 805 2019 19. 31 1042 | 14. 34 859 2020 19. 37 2020 | 14. 47 803 2021 19. 41 1149 | 14. 59 908 2022 19. 46 2010 | 14. 69 1003 2023 19. 54 1108 | 14. 9 960 2024 19. 54 2090 | 15. 09 984 2025 19. 65 1000 | 15. 31 956 2026 19. 77 2150 | 15. 37 1049 2027 19. 84 1022 | 15. 41 950 2028 19. 94 2141 | 15. 56 974 2029 20. 03 1028 | 15. 67 961 030 20. 07 2196 | 15. 9 1024 2031 20. 1 924 | 16. 08 1090 2032 20. 15 2230 | 16. 12 989 2033 20. 11 897 | 16. 23 1051 2034 20. 13 2257 | 16. 33 1062 2035 20. 21 877 | 16. 5 1052 2036 20. 24 2286 | 16. 59 1052 2037 20. 23 865 | 16. 72 1094 2038 20. 29 2236 | 16. 83 1097 2039 20. 34 964 | 16. 97 1145 2040 20. 37 2261 | 17. 07 1133 2041 20. 48 916 | 17. 2 1133 2042 20. 52 2251 | 17. 5 1081 2043 20. 57 958 | 17. 37 1052 2044 20. 61 2331 | 17. 5 1095 2045 20. 66 847 | 17. 64 1082 2046 20. 74 2362 | 17. 78 1139 2047 20. 85 861 | 17. 9 1060 2048 20. 88 2518 | 17. 91 1097 2049 20. 82 703 | 18. 04 1160 2050 20. 77 2250 | 18. 16 1238 2051 20. 73 964 | 18. 3 1220 2052 20. 82 2231 | 18. 37 1211 2053 20. 92 930 | 18. 55 1135 2054 20. 96 2302 | 18. 72 1271 2055 21. 913 | 18. 85 1284 2056 21. 2 2254 | 18. 87 1189 2057 21. 28 902 | 18. 96 1224 2058 21. 29 2392 | 19. 09 1210 2059 21. 28 760 | 19. 23 1282 2060 21. 28 2463 | 19. 34 1150 2061 21. 29 735 | 19. 38 1196 2062 21. 38 2416 | 19. 39 1265 2063 21. 52 780 | 19. 47 1299 2064 21. 5 2431 | 19. 49 1268 2065 21. 51 824 | 19. 5 1348 2066 21. 53 2457 | 19. 55 1249 2067 21. 65 758 | 19. 62 1312 068 21. 73 2583 | 19. 65 1216 2069 21. 71 672 | 19. 85 1184 2070 21. 75 2334 | 19. 85 1291 2071 21. 66 870 | 19. 97 1248 2072 21. 68 2375 | 20. 06 1168 2073 21. 73 869 | 20. 12 1319 2074 21. 77 2302 | 20. 14 1316 2075 21. 77 894 | 20. 24 1230 2076 21. 74 2400 | 20. 32 1313 2077 21. 77 885 | 20. 4 1328 2078 21. 76 2316 | 20. 39 1297 2079 21. 78 911 | 20. 41 1343 2080 21. 78 2410 | 20. 5 1339 2081 21. 83 776 | 20. 44 1299 2082 21. 81 2550 | 20. 49 1286 2083 21. 8 712 | 20. 6 1303 2084 21. 88 2356 | 20. 69 1234 2085 21. 88 927 | 20. 75 1328 2086 21. 87 2318 | 20. 65 1347 2087 21. 87 856 | 20. 66 1405 2088 21. 89 2396 | 20. 64 1296 2089 21. 9 875 | 20. 7 1327 2090 21. 93 2161 | 20. 7 1341 2091 22. 0 997 | 20. 74 1405 2092 22. 04 2458 | 20. 69 1328 2093 22. 7 781 | 20. 79 1246 2094 22. 09 2350 | 20. 81 1344 2095 22. 24 854 | 20. 83 1272 2096 22. 36 2432 | 20. 88 1293 2088 21. 98 2146 | 20. 6 1312 2089 22. 07 1051 | 20. 69 1368 2090 22. 14 2286 | 20. 71 1260 2091 22. 19 880 | 20. 83 1323 2092 22. 2 2386 | 20. 87 1316 2093 22. 24 869 | 20. 99 1336 2094 22. 33 2388 | 20. 96 1420 2095 22. 46 839 | 20. 97 1355 2096 22. 52 2362 | 20. 95 1389

In conclusion, the hypothesis was accepted in the fact the environmental factors plays a huge role in the survival of the birds. The clutch size is very important in determining whether the population of the birds goes extinct on either island. Clutch size is the number of eggs that a female bird lays in her nest and in these experiment, birds mate for life and live for one year and each female produces only one clutch of eggs per year. References This is a hanging indent. To keep the hanging indent format, simply delete this line of text using the backspace key, and replace the information with your reference entry.

Free Essays

Microbiology 311 Lab Report

Rebekah Worley February 21, 2012 Mitchell Section 4 Biol 311 Staining and Identifying Unknown Bacteria Introduction: The microbiology lab up to this point has been used to teach the students how to stain and identify bacteria. There are several types of staining through which the bacteria can be identified based on the color and shape. The staining methods used in the lab are Gram Staining, Capsule Staining, Endospore Staining, and Acid Fast staining. One of the most significant method of staining is the Gram Staining, as it is highly dependent (McCarthy, 25).

In the specific experiment that was done, Gram Staining was used and the bacteria that was found was purple and round (cocci) shaped. Through this the bacteria was identified as Staphylococcus epidermis. Material and Methods: The first step to identifying the bacteria was to heat fix it to the slide. The materials used were a slide, water, a Bunsen Burner, bibulous paper and clothes pin. The unknown bacteria was in a vial in solid form. The steps on page 19 and 20 of the Customized Biol 311 General Microbiology Laboratory Manual were followed to heat fix the bacteria.

After this gram staining was used to identify the unknown bacteria. The materials used for gram staining include the slide the was heat fixed, bibulous paper, crystal violet, distilled water, Gram’s iodine, 95% ethyl alcohol, safranin, oil and a microscope. The steps on page 26 of the Customized Biol 311 General Microbiology Laboratory Manual were used to stain the bacteria. Several changes were made in the procedure. The crystal violet was on the slide for 1 minute rather than 20 seconds. The decolorizing step was used with alcohol for 10 seconds rather than 20 seconds.

The only other change was that the safranin was on the slide for 1 minute instead of the recommended 20 seconds. The slide was put under the microscope at 1000x magnification using oil immersion. Results: When looking under the microscope the bacteria was found to be purple and cocci shaped. Because of the specific color and shape of the bacteria it was easily identifiable as Staphylococcus epidermis. From this it is seen that only a Gram stain was necessary to identify the bacteria. Discussion: From this experiment it is seen that bacteria is easily identified when stained correctly.

Going through the procedure with accuracy is vital, and when done right the bacteria is clear and concise. When the bacteria was stained in this experiment the color was difficult to determine at first. After exploring the bacteria on the slide it was seen to be mainly purple. If the staining had not been done properly it would have been a lot more difficult to distinguish between bacteria. This was an important thing to learn because staining is so vital in identifying unknown bacterium. Works Cited McCarthy, Charlotte M and Harold Benson. Customized Biol 311 General Microbiology Laboratory Manual. 2nd. ed. New York. McGraw-Hill 2002 Print.

Free Essays

Bottle Biology

Bottle Biology Project I made a two-layered bottle ecosystem. In the bottom layer, there is an aquatic ecosystem. In the aquatic ecosystem, there is one organism; a goldfish. In the top layer, there is a land ecosystem. There are many plants and other pudding flowers. This is a good example of two organisms from different ecosystems. There were not as many steps as I thought there would be involved in building the bottle itself. First I emptied out two two liters of pop. I then cut off the tops of both bottles, and threw out one of the bases.

In the leftover base, I poured water, aquatic gravel, and a fake plant for the fish. I then put the fish in it’s new happy home. In order to feed him, I cut out a flap leading to the water that I can put fish food in. After that, I began working on the top layer. I placed one of the tops, with the cap still on, about half an inch into the original base. I taped it securely into the base, to ensure that the whole upper layer would not crush the fish. Then I put my plants into the half-built top layer. After that I placed my second bottle top on top of the base, creating another funnel.

I taped the top securely on, finishing the bottle. I can screw and unscrew the cap whenever I need to give the plant water. Both the fish and plant do not need much caring for. The plant needs a little bit of water every day, and the fish needs food about twice a day, but that is not nearly what I thought it would take to maintain these organisms. I enjoyed this project; it was very interesting to make two small ecosystems. If I had the chance to do it again with two different organisms I would definitely do it. ———————– AJ Keith 5/19/11 Period 3

Free Essays

Ap Biology Paper

August 20, 2012 AP Biology Paper thing Daniel Gildenbrand Many scientists have contributed to the subjects of nature, evolution, medicine, and to the development of how experiments are executed. In this essay I will go over four scientists, their experiments, and how those experiments benefited the scientific community and the way we currently live our lives. These four scientists greatly contributed to science and were arguably the greatest contributors to their field of study.

First, we have Francesco Redi and his famous experiments challenging the previous assumption that maggots underwent “spontaneous generation”, a theory about the formation of living organisms without descent from similar organisms, and naturally spawned from rotting meat. Redi disproved this theory with his experiments. In one of those experiments, Redi took three groups of jars: in the first jar of each group he put an unknown object; in the second, a dead fish; and in the third, a rotting piece of meat.

The first group of jars was left open with no lid, the second group was covered in a woven piece of gauze, so that only air could get into the jar, and the third group was firmly sealed with a lid. After a few days of wait, Francesco noted that maggots appeared in the open jars where he saw flies had landed. The group of jars covered with the gauze had maggots on top of the gauze because the flies could smell the rotting meat so they laid their eggs there. Finally, he observed jars sealed with a lid had no maggots.

With this experiment he disproved the theory of abiogenesis. His contribution to the scientific community did not end with just the results of his experiments as he was credited with the development of the “controlled experiment. ” Controlled experiments changed the way we conduct experiments and greatly increased the accuracy of our results. The famous quote “Omne vivum ex ovo” (“All life comes from an egg”) is commonly associated with Redi’s experiments. A great contributor to the field of medicine and microbiology was Louis Pasteur.

He was famous for his experiments with micro-organisms and for inventing the S-flask, which is now of great use in scientific experiments. Louis’ experiments saved the silk industry, and solved problems with the manufacture of alcoholic drinks. Most importantly, Pasteur invented the process now known as pasteurization. While working with the germ theory, which he bettered with his research, Pasteur proved that micro-organisms such as bacteria were responsible in the souring of alcoholic drinks such as beer and wine.

He also discovered that microbes where infecting silk worm eggs and advocated that only disease-free eggs should be selected, which saved the industry. Another one of Pasteur’s accomplishments was when he confirmed the disproval of abiogenesis through his experiments. In the experiment, he put exposed boiled broth into two groups of S-flasks, which he invented to slow the growth of bacteria in test tubes. Then, he covered one of the groups of flasks with a filter designed to prevent any particles from entering the tube.

The other group was group of S-flasks was left alone (the S-flasks also only allowed a minimal amount of particles to enter the tube). He concluded that bacteria only grew in the flasks after they were broken open; therefore, the microbes had to come from the outside, in the form of spores on dust particles. To counter the growth of these bacteria, he developed “pasteurization” which is a process that kills bacteria within a liquid by heating then cooling the liquid. Pasteurization is now used just about anywhere beverages are manufactured to prevent any bacteria from entering the products.

Finally, Louis Pasteur’s arguably greatest contribution to science was bettering the concept of vaccination. When Pastuer was working on a problem causing chickens to die from a virus called “chicken cholera” on a farm, he exposed some of the healthy chickens to a weaker form of the virus. After returning from a month-long vacation, Louis discovered that the chickens did not die from the disease, like the others, but had actually grown immune to the disease and were completely healthy.

He applied the same principle of vaccination to a quickly spreading epidemic called anthrax. Louis Pasteur’s contributions to science were vast and if we think about it, his research has forever changed the way that we live our lives today. Charles Darwin was an English naturalist who was dubbed the father of evolution. His work included establishing the fact that all species descended from common ancestors and describing a process he called natural selection in which different species struggled for life, leaving only the ones that adapted better to survive.

Darwin has often been called one of the most influential figures in human history. His work undoubtedly affected people’s view on life and his theory of evolution transformed the way we think about the natural world. Darwin collected his research from many different places but his most influential research was gathered along his voyage on the Beagle. In 1831 Darwin tagged along the ship The Beagle on a survey voyage. When he got to the Galapagos Islands, he noticed that each island had similar finches that had their own distinctive features.

He then noticed that these features corresponded with the environment that the birds lived in and what they had to hunt. He explained the situation with the theories of evolution and natural selection. He stated that the finches had originated from a similar ancestor and had evolved their characteristics to adapt to each sub-environment on the islands. Then, by natural selection, the finches that were better suited for their environment where left to breed and thrive on the islands. This is what we would call today, “Survival of the fittest. What Darwin accomplished with his research is vital to the scientific community and what we learn today. His work explains why many things exist as they do and how some things came to be. Finally, we had Sir Alexander Fleming, who discovered the “wonder drug” penicillin. Fleming had discovered the world’s first anti-biotic, or bacteria killer. Penicillin is a drug that kills bacteria in many forms and is widely used in medicine and is essential in healing infections. As important as penicillin may be, it was found in a very strange way.

When Fleming was leaving his laboratory for a vacation, he had stacked all his cultures of staphylococci on a bench in a corner of his laboratory. When he returned, he started to show some of the samples to his lab assistant and randomly noticed that one of the samples had grown a mold. He thought nothing of it until he also noticed that the mold had killed the staphylococci sample that was in the dish. Fleming saw that this mold had great potential. He spent several weeks growing more of the mold and, with the help of a colleague, he figured out that it was a Penicillium mold.

He continued to run experiments with the mold and figured out that it killed many different types of harmful bacteria. But the most important characteristic of the mold was that it did no harm to the human body. Since Fleming was not a chemist, he could not isolate the actual antibacterial element within the mold and use it as medicine. Later on though, two chemists by the names of Florey and Chain managed to make penicillin a usable product. Fleming’s discovery of penicillin greatly benefited the evolution of medicine and has been a vital asset in fighting bacteria and illness.

Francis Redi, Louis Pasteur, Charles Darwin, and Alexander Fleming each greatly benefited the scientific community. Their research and discoveries allowed for great advancements in medicine, knowledge, and helped shine light on things previously unknown. Francesco Redi and Louis Pasteur both disproved the theory of spontaneous generation. Charles Darwin changed the way we view species and the natural world with his theories of evolution and natural selection. Lastly, Alexander Flemings advanced field of medicine by discovering the miracle drug of penicillin.

Whether it was by Darwin giving us new knowledge on the natural world or by Redi, Louis, and Pasteur pushing medicine further, these fours scientists greatly improved our lives and forever changed the way we live them. Bibliography Francesco Redi Meat and Maggots 1. “Francesco Redi and Controlled Experiments. ” The Church and Science:Conflict or Complement. N. p. , n. d. Web. 7 Sept. 2012. <http://www. scientus. org/Redi-Galileo. html>. 2. “Redi Experiment. ” Kent School District. N. p. , n. d. Web. 7 Sept. 2012. <http://www1. kent. k12. wa. us/staff/timly 3. “Francesco Redi and Spontaneous Generation.  Louis Pasteur – The Life, Work and History – Microbiology, Chemistry, Fermentation and Beer. N. p. , n. d. Web. 7 Sept. 2012. <http://www. pasteurbrewing. com/Articles/spontaneous-generation/francesco-redi-and-spontaneous-generation. html>. Louis Pasteur Micro-organisms and the flask 1. “Louis Pasteur Biography. ” Bio. com. A&E Networks Television, n. d. Web. 07 Sept. 2012. <http://www. biography. com/people/louis-pasteur-9434402>. 2. “BBC – History – Louis Pasteur. ” BBC – Homepage. N. p. , n. d. Web. 7 Sept. 2012. <http://www. bbc. co. uk/history/historic_f 3.

Bellis, Mary. “Louis Pasteur – Germ Theory of Disease. ” Inventors. N. p. , n. d. Web. 7 Sept. 2012. <http://inventors. about. com/od/pstartinv Charles Darwin Evolution, Survival, Natural Selection 1. “BBC – History – Charles Darwin. “BBC – Homepage. N. p. , n. d. Web. 7 Sept. 2012. <http://www. bbc. co. uk/history/historic_figures/dar 2. “Darwin’s Theory Of Evolution. “Darwin’s Theory Of Evolution. N. p. , n. d. Web. 7 Sept. 2012. <http://www. darwins-theory-of-evolution. com/>. 3. “Darwin’s Theory. ” BioWeb. N. p. , n. d. Web. 7 Sept. 2012. <http://bioweb. cs. earlham. du/9-12/evolution/HTML/theory. html>. Alexander Fleming Molds and Penicillin 1. Rosenberg, Jennifer. “Alexander Fleming Discovers Penicillin. ” 20th Century History. N. p. , n. d. Web. 7 Sept. 2012. <http://history1900s. about. com/od/medicaladva 2. “Sir Alexander Fleming – Biography. “Nobelprize. org. N. p. , n. d. Web. 7 Sept. 2012. <http://www. nobelprize. org/nobel_prizes/medicine/laureates/1945/fleming-bio. html>. 3. “Alexander Fleming and Penicillin. “History Learning Site. N. p. , n. d. Web. 7 Sept. 2012. <http://www. historylearningsite. co. uk/alexander_fleming_and_penicillin. htm

Free Essays

Biological Macromolecules

The vast complexity of a single organism, including humans, is attributed to the intricacies found within their bio molecular contents. These contents are the very small, specific pieces that make up everything from the walls of our cells, the shape of the proteins that form functional structures of the cells, or even the basic units that contain the energy required to fuel life.

The knowledge of these biomolecules can be used to analyze food contents to allow scientists to manipulate or identify the healthiest foods, to discover new molecules that can be compounded in life saving medications, or to identify disorders in our own molecules that can be corrected. These are among some of the uses knowledge of these bio molecules could provide us. In this experiment, we are going to analyze the content of two different types of substances, a banana and some curry, to identify whether or not they contain starches, sugars, or proteins.

This experiment is a very basic test of biomolecular content where identifying agents are mixed with the substances to determine their content. Our hypothesis is that the banana will contain both sugars and starches, but will not contain protein. This hypothesis is supported by the fruit’s sweet taste and starch-like structure, possibly similar to a potato, which, based on prior knowledge, is known to be a ‘starchy-food’. Our hypothesis for curry is less precise. The curry was an original recipe and the ingredients were unknown.

Based, however, on the taste and texture alone, in comparison with other known starchy foods, we would hypothesize that it does contain starch. Protein and sugar content, however, are unknown. Specifically, we predict that when added to a banana mixture, the starch and sugar identifiers will react, and when added to a curry mixture, starch identifier will react, but the two other identifiers will be unknown. Specifics of this prediction will be discussed in the next section.

Methods – To perform this study, we first mixed controls based on known substances in order to provide a baseline comparison against our experimental data. We had three identifier solutions known to react in some way to a corresponding biomolecule, and they were pippetted following strict guidelines (see below under “Pipetting Methods. ”) These identifiers were biuret, iodine, and DNSA. We tested these identifiers with solutions known to exclusively contain protein, sugar, and starch, as well as mixing them with pure water to identify what ‘no reaction’ would look like.

The test of controls and indicators shows that biuret identifies protein, iodine identifies starches, and DNSA identifies sugar. There are some complications, however, in that DNSA also reacted (however not as strong) with proteins. This means that in substances that biuret indicates protein content, DNSA will show a reaction, regardless of whether or not there is sugar in the solution. The sugar reaction is much greater than protein, but this could still possibly give inconclusive results in anything that contains proteins.

Proteins also interact with iodine however at a much different, distinguishable way so as to be less likely to influence our qualitative results. Once our controls were created and the reactions between the biomolecules and their indicators were better understood, the next part of our method involved preparing our experimental. To do this we created three tubes of each experimental substance. We diluted banana mush with water and placed it in three tubes, and diluted the curry and did the same. We then placed in the tube the appropriate amount of indicator solution, observed the results, and compared them with our controls.

Free Essays

Origin of Eukaryotes

* The origin of eukaryotes is important to understand the origin of modern complex cells. There are three main separate theories that hypothesize the origins: the three-domain system, eocyte theory, and endosymbiosis. Each one have there own merits and evidence supporting. These theories suggest the evolution of cells from the most primitive prokaryotes, unicellular organism having cells lacking membrane-bound nuclei, to the most complex eukaryotes, single or multicellular organisms with a membrane enclosed nucleolus and organelles.

The Three Domain Hypothesis refers to the proposal by Carl Woese in 1990 that; archaebacteria form a monophyletic group, this clade is sufficiently different from all other prokaryotes to deserve elevation to a separate Domain called Archaea (the other two Domains are Bacteria and Eukarya each arising from a progenote), eukaryotes are more closely related to archaebacteria than to other prokaryotes, and the root of the universal tree of life lies in the branch leading to Bacteria. The three-domain system met with some opposition on the differences between archaea and bacteria.

Research of large subunits of RNA polymerase, some aminoacyl-tRNA synthetases (aspartyl, leucyl, tryptophanyl, and tyrosyl), and outer membrane molecules distinctions indicated that Woese was right in the classification and that these organisms were so genetically distinct (in the 165rRNA genes and differences in cell structures) that they needed their own domains. * In the 1984 James Lake theorized eukaryotes evolved from a specific group of ancestrial archea, the eocyte. The idea that eukaryotes could have arisen from a lineage of prokaryotes, using expanded molecular sequence datasets and phylogenetic approaches.

Using a matrix of amino acid sites, traditional methods such as maximum parsimony resulted in the 3-domains topology, but an eocyte tree was obtained when maximum-likelihood and Bayesian analyses were performed. In sum this analyses provide support for the eocyte tree, rather than the 3-domains tree. This is supported by the concept that eukaryotic nucleo-cytoplasm evolved from within archaebacteria. Eukaryotes would have had to replace their old lipid synthesis with a eubacterial-type system since the operational genes of eukaryotes are primarily eubacterial, not archaebacterial (National Academy of Science of the United states 2008).

Eukaryotes are seen as an evolutionary marvel for they can pack hundreds of energy-generating mitochondria into a single cell. Hundreds of millions of years ago, eukaryotes formed permanent colonies in which certain cells dedicated themselves to different tasks, such as nutrition or excretion, and whose behavior was well coordinated. This specialization allows them to grow, and evolving into new elaborate purposes. These cells have a true nucleus, bound by a double membrane. Prokaryotic cells have no nucleus.

The purpose of the nucleus is to sequester the DNA- functions of the eukaryotic cell into chamber for increased efficiency. This function is unnecessary for the prokaryotic cell, because it is much smaller in size; materials within the cell are close together. There is an area of nuclear DNA unbound by a membrane called a nucleoid. Eukaryotic cells are larger, more advanced and have a higher output of energy in comparison to Prokaryotes. Lynn Margulis (1970) defined the hypothesis of Endosymbiosis as the engulfment of one cell by another larger cell, with the engulfed cell evolving into an organelle.

Margulis claimed that as a result of communal and parasitic lives, bacterial cells turned into plants and animals through endosymbiosis. In this theory, plant cells developed when a cyanobacteria (chloroplast) was swallowed by another bacterial cell and animal cells were formed through mitochondria being engulfed by host cell. Another example is between a termite and microorganisms in its gut. The termite consumes wood, but it cannot digest it, the protozoan’s in the termite’s gut break down the cellulose into simple sugars which both organisms can digest.

When the protozoa digest the wood cellulose, they release acetic acid and other acids that the host termite is able to metabolize. Thus, the termite and the protozoan uniquely supply food for each other (Applied and Environmental Microbiology 2005). The origin of the eukaryotic cell was important, since they include all complex cells and almost all multi-cellular organisms. The timing these events is hard to determine, each hypothesis have there own evidence that support itself. Until further evidence can be found scientists can only speculate on the origins of Eukaryotes.

Free Essays

Human Biology Digestive and Urinary System Essay

Abstract The human body needs to maintain proper homeostasis to survive. There are several different organ systems in the human body. Two of those systems are the digestive system and the urinary system. Both systems remove waste from the body but in an entirely different way. They also maintain homeostasis within our blood stream. Both systems are critical for survival. This paper will describe how each of those systems works on its own and also how they work together to maintain homeostasis for the body.

How the Urinary and Digestive Systems Work Together to Maintain Homeostasis The digestive system works to bring nutrients into the body with a series of hollow organs working together extending from the mouth to the anus. These hollow organs are the mouth, pharynx, esophagus, stomach, small intestine, large intestine, rectum, and anus. These hollow organs make up the gastrointestinal (GI) tract. The GI tract is aided by four accessory organs, the salivary glands, liver, gallbladder, and pancreas. Johnson) There are five basic processes of the digestive system. These processes are motility, secretion, digestion, absorption, and excretion. Motility is the mechanical processing and movement of food taken into the body. Chewing breaks food into smaller pieces, and two types of movement mix the contents of the lumen and propel it forward. The lumen is the inside lining of the GI tract. Secretion is the fluid, digestive enzymes, acid, alkali, bile, and mucus that are secreted into the GI tract at various places.

Digestion is where the contents of the lumen are broken down mechanically and chemically into smaller and smaller particles, culminating in nutrient molecules. Absorption is what happens when the nutrient molecules pass across the GI tract and into the blood. Elimination is all of the undigested material is eliminated from the body through the anus. (Johnson) These GI tract and the four accessory organs of the digestive tract work together to complete the five processes in order to bring nutrients into the body, and eliminate waste. The large intestine absorbs nutrients and eliminates waste.

The small intestine absorbs nutrients and water. The water and nutrients absorbed from the intestines go into the blood stream . (Johnson) The urinary system consists of the kidneys, ureters, bladder, and urethra. The ureters, bladder, and urethra transport and store urine until it is eliminated from the body. The kidneys produce urine. Urine is the nitrogenous waste removed from the blood stream. It is essential to the body to remove this waste in order to maintain homeostasis. (Johnson) The kidneys perform all of the main functions in the urinary system.

They regulate water levels in the body. When you take in water every day it is up to the kidneys to excrete the excess water or to conserve as much as possible. The kidneys have a great capacity to adjust water excretion as necessary. Normally with a minimum of a half liter per day to one liter per hour. (Johnson) The kidneys also regulate the nitrogenous waste and other solutes in our blood. One waste that is toxic to our cells is ammonia. Ammonia is detoxified quickly by the liver by being combined with carbon dioxide to create urea.

Urea is the main waste product in urine. Sodium and chloride are both regulated by the kidneys as well. Sodium and chloride are both very important to determine the volume of extracellular fluids, like blood. This directly affects blood pressure. (Johnson) Other substances that the kidneys regulate are potassium, calcium, hydrogen, and creatinine. It is up to the kidneys to maintain homeostasis with each of these substances. Creatinine is a waste product that is produced during metabolism. This is one of the wastes that give urine a yellow color. Johnson) The digestive system removes nutrients and water from the food that we eat and drink and transports it to our blood stream. Any solid wastes that are unable to be digested are then eliminated from the GI tract. Our urinary system then removes any of the unwanted and unneeded substances and wastes from the blood stream and excretes them in urine. This is how homeostasis is maintained in our body with waste, so that there is no toxic build up in our body from certain substances. Homeostasis is critical to be maintained within the body for survival.

Homeostasis is the body’s ability to maintain relatively stable internal conditions even though the outside world is continuously changing. (Marieb) All living things must maintain an internal environment compatible with life, and the range of chemical and physical conditions compatible with life is very narrow. (Johnson) In order for the digestive and urinary systems to work together to maintain homeostasis both systems must be functioning properly. First we consume food and water. Then our digestive system absorbs the nutrients and water into our blood stream.

Once the nutrients and water is in our blood stream our urinary system the filters the blood and removes any additional waste and maintains the proper homeostasis with the nutrients we consume. If our digestive system is not functioning properly then we are not able to absorb the proper nutrients and fluids in order to allow our kidneys to filter our blood and maintain homeostasis. If our urinary system is not functioning properly than the nutrients and fluids we consume can cause a buildup in our blood stream of toxic wastes and fluids and throw off homeostasis.

Either way it would be detrimental to our body for this to happen. Our blood pressure would be affected severely and this would cause issues with not only our cardiovascular system but also our respiratory system. It is critical to keep both systems healthy to ensure that our body’s have the proper water and nutrients to survive and that all waste is secreted from our systems. References Johnson, Michael D. Human Biology: Concepts and Current Issues-sixth edition. Pearson Education. 2012. Print. Marieb, Elaine Nicpone. Essentials oh Human Anatomy and Physiology-tenth edition. Pearson Education. 2012. Print.

Free Essays

Biology Revision

Majeed Thaika Year 10-11  Contents 1 Cells  pg-05 -Animal and plant cells (pg-05) -Specialised cells (pg-06) -diffusion (pg-07) -osmosis (pg-08) 2 Plants . pg-09 -photosynthesis (pg-09) -Factors affecting photosynthesis (pg-10) -Plants and minerals (pg-11) 3 Food Chains and Cycles pg-12 -Food chain (pg-12) -Energy transfer (pg-13) -Pyramids of biomass (pg-15) -efficiency of food production (pg-15) -calculating energy efficiency (pg-16) Shorter food chains (pg-16) carbon cycle (pg-17) 4Enzymes and Digestion  pg-18 -What are enzymes? (Pg-18) -Temperature and enzymes (Pg-18) -Ph and enzymes (Pg-19) -enzymes and respiration (Pg-20) -digestive system (Pg-20) -Enzymes and digestion (Pg-21) -Other substances in digestion (Pg-22) -Enzymes in industry (Pg-23) 5Homeostasis  pg-24 -Removing waste products (Pg-24) -Controlling blood glucose (Pg-25) -Diabetes (Pg-25) -Temperature regulation (Pg-26) – Temperature regulation – Higher (Pg-26) 6Hormones  pg-27 -Hormones and glands (pg-28) hormones in the menstrual cycle (pg-29) -Controlling fertility (pg-31) 7The Nervous System  pg-31 -receptors and effectors (pg-31) -Neurones (pg-33) -Reflex action (pg-34) 8Defending against infection  pg-35 -pathogens-bacteria (pg-35) -pathogens-virus (pg-36) -white blood cells (pg-36) -more about white blood cells (pg-37) -vaccination (pg-38) -antibiotics (pg-38) 9Diet and Exercise  pg-40 -nutrients (pg-40) -metabolic rate(pg-41) -the right amount of food (pg-41) -cholesterol(pg-42) -salt (pg-43) 10Adaptation  pg-43 -Adaptation-cold climates (pg-43) -Adaptation-hot climates (pg-44) 11Characteristics and Classification  pg-45 -genetic engineering (pg-45) -selective breeding (pg-45) -changing the characteristics of a species (pg-46) -classification (pg-47) -difficulties with classification (pg-48) 12The Heart  pg-49 -the circulatory system (pg-49) -arteries and veins (pg-50) -the heart (pg-50) -causes of heart disease (pg-51) 13Extra  pg-51 -sex hormones (pg-51) competition (pg-52) -The nitrogen cycle -the water cycle Cells All animals and plants are made of cells. Animal cells and plant cells have features in common, such as a nucleus, cytoplasm, cell membrane, mitochondria and ribosomes. Plant cells also have a cell wall, and often have chloroplasts and a permanent vacuole. Note that cells may be specialized to carry out a particular function. Dissolved substances pass into and out of cells by diffusion. Water passes into and out of cells by osmosis. Animal and plant cells Function of cells which animal and plant cells have in common:- Part| Function| ucleus| contains genetic material, which controls the activities of the cell| cytoplasm| most chemical processes take place here, controlled by enzymes| cell membrane| controls the movement of substances into and out of the cell| mitochondria| most energy is released by respiration here| ribosomes| protein synthesis happens here| Extra parts of plant cells:- Part| Function| cell wall| strengthens the cell| chloroplasts| contain chlorophyll, which absorbs light energy for photosynthesis| permanent vacuole| filled with cell sap to help keep the cell turgid|

Diagram: Generalized animal and plant cell Specialised cells Cells may be specialized for a particular function. Their structure will allow them to carry this function out. Here are some examples: Examples of the functions of cells:- Cell| Function| Adaption| Leaf cell| Absorbs light energy for photosynthesis| Packed with chloroplasts. Regular shaped, closely packed cells form a continuous layer for efficient absorption of sunlight. | Root hair cell| Absorbs water and mineral ions from the soil| Long ‘finger-like’ process with very thin wall, which gives a large surface area. |

Sperm cell| Fertilizes an egg cell – female gamete| The head contains genetic information and an enzyme to help penetrate the egg cell membrane. The middle section is packed with mitochondria for energy. The tail moves the sperm to the egg. | Red blood cells| Contain haemoglobin to carry oxygen to the cells. | Thin outer membrane to let oxygen diffuse through easily. Shape increases the surface area to allow more oxygen to be absorbed efficiently. No nucleus, so the whole cell is full of haemoglobin. | Diffusion Dissolved substances have to pass through the cell membrane to get into or out of a cell.

Diffusion is one of the processes that allow this to happen. Diffusion occurs when particles spread. They move from a region where they are in high concentration to a region where they are in low concentration. Diffusion happens when the particles are free to move. This is true in gases and for particles dissolved in solutions. Particles diffuse down a concentration gradient, from an area of high concentration to an area of low concentration. This is how the smell of cooking travels around the house from the kitchen, for example. Examples of diffusion Location| Particles move| From| To|

Gut| digested food products| gut cavity| blood in capillary of villus| Lungs| oxygen| alveolar air space| blood circulating around the lungs| Two examples of diffusion down concentration gradients:- Remember, particles continue to move from a high to a low concentration while there is a concentration gradient. In the lungs, the blood will continue to take in oxygen from the alveolar air spaces provided the concent-ration of oxygen there is greater than in the blood. Oxygen diffuses across the alveolar walls into the blood, and the circulation takes the oxygen-rich blood away. Osmosis

Water can move across cell membranes because of osmosis. For osmosis to happen you need: * two solutions with different concentrations * a partially permeable membrane to separate them Partially permeable membranes let some substances pass through them, but not others. The animation shows an example of osmosis. Osmosis is the movement of water from a less concentrated solution to a more concentrated solution through a partially perm-eable membrane. The picture above shows how osmosis works. Eventually the level on the more concentrated side of the membrane rises, while the one on the less concentrated side falls.

When the concentration is the same on both sides of the membrane, the movement of water molecules will be the same in both directions. At this point, the net exchange of water is zero and there is no further change in the liquid levels. Osmosis is important to plants. They gain water by osmosis through their roots. Water moves into plant cells by osmosis, making them turgid or stiff so they that able to hold the plant upright. Plants Green plants absorb light energy using chlorophyll in their leaves. They use it to react carbon dioxide with water to make a sugar called glucose.

The glucose is used in respiration, or converted into starch and stored. Oxygen is produced as a by-product. This process is called photosynthesis. Temperature, carbon dioxide concentration and light intensity are factors that can limit the rate of photosynthesis. Plants also need mineral ions, including nitrate and magnesium, for healthy growth. They suffer from poor growth in conditions where mineral ions are deficient. Photosynthesis Photosynthesis is the chemical change which happens in the leaves of green plants. It is the first step towards making food – not just for plants but ultimately every animal on the planet.

During this reaction, carbon dioxide and water are converted into glucose and oxygen. The reaction requires light energy, which is absorbed by a green substance called chlorophyll. Cross-section through a leaf cell Photosynthesis takes place in leaf cells. These contain chloroplasts, which are tiny objects containing chlorophyll. The equation for photosynthesis is:- Plants absorb water through their roots, and carbon dioxide through their leaves. Some glucose is used for respiration, while some is converted into insoluble starch for storage. The stored starch can later be turned back into glucose and used in respiration.

Oxygen is released as a by-product of photosynthesis. Factors limiting photosynthesis Three factors can limit the speed of photosynthesis – light intensity, carbon dioxide concentration and temperature. Light intensity -Without enough light, a plant cannot photosynthesise very quickly, even if there is plenty of water and carbon dioxide. -Increasing the light intensity will boost the speed of photosynthesis. Carbon dioxide concentration Sometimes photosynthesis is limited by the concentration of carbon dioxide in the air. Even if there is plenty of light, a plant cannot photosynthesise if there is insuff-icient carbon dioxide.

Temperature -If it gets too cold, the rate of photosynthesis will decrease. Plants cannot photosynthesise if it gets too hot. -If you plot the rate of photosynthesis against the levels of these three limiting factors, you get graphs like the ones above. -In practice, any one of these factors could limit the rate of photosynthesis. Maximizing growth Farmers can use their knowledge of these limiting factors to increase crop growth in greenhouses. They may use artificial light so that photosynthesis can continue beyond daylight hours, or in a higher-than-normal light intensity.

The use of paraffin lamps inside a greenhouse increases the rate of photosynthesis because the burning paraffin produces carbon dioxide and heat too. Plants and minerals Plants need to take in a number of elements to stay alive. The most important are: * carbon * hydrogen * oxygen Plants get hydrogen and oxygen from water in the soil, and carbon and oxygen from carbon dioxide and oxygen in the atmosphere. Water and carbon dioxide are used to synthesise food during photosynthesis. Oxygen is used to release energy from food during respiration. In addition to these three elements, plants need a number of minerals for healthy growth.

These are absorbed through the roots as mineral ions dissolved in the soil water. Two important mineral ions needed by plants are: * Nitrate – for making amino acids, which are needed to make proteins * Magnesium – for making chlorophyll If a plant does not get enough minerals, its growth will be poor. It will suffer from deficiency symptoms: * deficient in nitrate – it will suffer from stunted growth * deficient in magnesium – it’s leaves will turn yellow The tomato plant on the left is healthy; the one on the right is growing in conditions where mineral ions are deficient Food Chains and Cycles

Food chains show the feeding relationships between living things. Pyramids of biomass reveal the mass of living material at each stage in a chain. The amount of material and energy decreases from one stage to the next. Food production is more efficient if the food chain is short, or if energy losses from animals are reduced. The carbon cycle shows how carbon moves from the atmosphere, through various animals and plants, then back to the atmosphere again. Food chains A food chain shows what eats what in a particular habitat. For example, grass seed is eaten by a vole, which is eaten by a barn owl.

The arrows between each item in the chain always point in the direction of energy flow – in other words, from the food to the feeder. The Sun is the ultimate source of energy for most communities of living things. Green plants absorb some of the Sun’s light energy to make their own food by photosynthesis. The other organisms in a food chain are consumers, because they all get their energy and biomass by consuming – eating – other organisms. It helps if you can recall the meaning of some common words used with food chains. Common words used with food chains and their meaning Word| Meaning|

Producers| Green plants – they make food by photosynthesis. | Primary consumers| Usually eat plant material – they are herbivores. For example rabbits, caterpillars, cows and sheep. | Secondary consumers| Usually eat animal material – they are carnivores. For example cats, dogs and lions. | Predators| Kill for food. They are either secondary or tertiary consumers| Prey| The animals that predators feed on. | Scavengers| Feed on dead animals. For example, crows, vultures and hyenas are scavengers. | Decomposers| Feed on dead and decaying organisms, and on the undigested parts of plant and animal matter in faeces. Energy transfer Energy is transferred along food chains from one stage to the next. But not all of the energy available to organisms at one stage can be absorbed by organisms at the next one. The amount of available energy decreases from one stage to the next. Some of the available energy goes into growth and the production of offspring. This energy becomes available to the next stage, but most of the available energy is used up in other ways: * energy released by respiration is used for movement and other life processes, and is eventually lost as heat to the surroundings energy is lost in waste materials, such as faeces All of the energy used in these ways returns to the environment, and is not available to the next stage. The animation shows how the level of available energy goes down as it is transferred through a temperate forest food chain. Most food chains are pretty short. There are rarely more than four stages, because a lot of energy is lost at each stage. Pyramids of biomass Biomass means the mass of living material at a stage in a food chain. The biomass goes down as you go from one stage to the next, just like the amount of energy.

A pyramid of biomass is a chart, drawn to scale, showing the biomass at each stage in a food chain. The bars become narrower as you reach the top. This pyramid of biomass is for the food chain: Oak tree > caterpillar > blue tit > sparrowhawk Note that you do not need to draw the organisms. But you must draw your pyramid of biomass to scale. Each bar should be labelled with the name of the organism. Efficiency of food production The efficiency of food production can be improved by reducing the amount of energy lost to the surroundings. This can be done by: * preventing animals moving around too much keeping their surroundings warm Mammals and birds maintain a constant body temperature using energy released by respiration. As a result, their energy losses are high. Keeping pigs and chickens in warm sheds with little space to move around allows more efficient food production. But this raises moral concerns about the lives of such animals. In reality, a balance must be reached between the needs of farmers and consumers and the welfare of the animals. Calculating energy efficiency This bullock has eaten 100 kJ of stored energy in the form of grass, and excreted 63 kJ in the form of faeces, urine and gas.

The energy stored in its body tissues is 4 kJ. So how much has been used up in respiration? The energy released by respiration = 100 – 63 – 4 = 33 kJ Only 4 kJ of the original energy available to the bullock is available to the next stage, which might be humans. The efficiency of this energy transfer is: Efficiency = 4/100 x 100 = 4% Shorter food chains Food production is more efficient if the food chain is short, because a higher percentage of energy is available to us. The carbon cycle All cells – whether animal, plant or bacteria – contain carbon, because they all contain proteins, fats and carbohydrates.

Plant cell walls, for example, are made of cellulose – a carbohydrate. Carbon is passed from the atmosphere, as carbon dioxide, to living things, passed from one organism to the next in complex molecules, and returned to the atmosphere as carbon dioxide again. This is known as the carbon cycle. Removing carbon dioxide from the atmosphere Green plants remove carbon dioxide from the atmosphere by photosynthesis. The carbon becomes part of complex molecules such as proteins, fats and carbohydrates in the plants. Returning carbon dioxide to the atmosphere Organisms return carbon dioxide to the atmosphere by respiration.

It is not just animals that respire. Plants and microorganisms do, too. Passing carbon from one organism to the next When an animal eats a plant, carbon from the plant becomes part of the fats and proteins in the animal. Microorganisms and some animals feed on waste material from animals, and the remains of dead animals and plants. The carbon then becomes part of these microorganisms and detritus feeders. Materials from living things decay because they are digested by microorganisms. This process happens faster in warm, moist conditions with plenty of oxygen. Decay can be very slow in cold, dry conditions, and when here is a shortage of oxygen. Enzymes and digestion Enzymes are biological catalysts. There are optimum temperatures and pH values at which their activity is greatest. Enzymes are also proteins, and usually denatured above about 45? C. Enzymes are important in respiration. Aerobic respiration releases energy from glucose. What are enzymes? Enzymes are biological catalysts – catalysts are substances that increase the rate of chemical reactions without being used up. Enzymes are also proteins that are folded into complex shapes that allow smaller molecules to fit into them.

The place where these substrate molecules fit is called the active site. The pictures show how this works. In this example, two small molecules join together to make a larger one. If the shape of the enzyme changes, it’s active site may no longer work. We say the enzyme has been denatured. They can be denatured by high temperatures or extremes of pH. Note that it is wrong to say the enzyme has been killed. Although enzymes are made by living things, they are proteins, and not alive. Temperature and enzymes As the temperature increases, so does the rate of reaction. But very high temperatures denature enzymes.

The graph shows the typical change in an enzyme’s activity with increasing temperature. The enzyme activity gradually increases with temperature until around 37? C, or body temperature. Then, as the temperature continues to rise, the rate of reaction falls rapidly, as heat energy denatures the enzyme. Temper-ature and enzyme activity PH and enzymes Changes in pH alter an enzyme’s shape. Different enzymes work best at different pH values. The optimum pH for an enzyme depends on where it normally works. For example, intestinal enzymes have an optimum pH of about 7. 5. Enzymes in the stomach have an optimum pH of about 2. H and enzyme activity Enzymes and respiration Enzymes in cells catalyse photosynthesis, protein synthesis – joining amino acids together, and aerobic respiration. Aerobic respiration Respiration is not the same thing as breathing. That is more properly called ventilation. Instead, respiration is a chemical process in which energy is released from food substances, such as glucose – a sugar. Aerobic respiration needs oxygen to work. Most of the chemical reactions involved in the process happen in tiny objects inside the cell cytoplasm, called mitochondria. This is the equation for aerobic respiration:

Glucose + oxygen > carbon dioxide + water (+ energy) The energy released by respiration is used to make large molecules from smaller ones. In plants, for example, sugars, nitrates and other nutrients are converted into amino acids. Amino acids can then join together to make proteins. The energy is also used: * to allow muscles to contract in animals * to maintain a constant body temperature in birds and mammals Enzymes are important in digestion. Digestion is the breakdown of carbohydrates, proteins and fats into small soluble substances that can be absorbed into the blood.

Lipases and proteases are used in biological detergents, and enzymes are used in the manufacture of food and drink. The digestive system Digestion is the breakdown of large molecules into smaller, soluble molecules that can be absorbed into the body. Digestion happens inside the gut, and relies on enzymes. This diagram will show you of the main parts of the gut: Enzymes and digestion The enzymes involved in respiration, photosynthesis and protein synthesis work inside cells. Other enzymes are produced by specialised cells and released from them; the digestive enzymes are like this. They pass out into he gut, where they catalyse the breakdown of food molecules. Different enzymes Different enzymes catalyse different digestion reactions. Enzymes and their reactions catalysed enzyme| reaction catalysed| amylase| starch > sugars| protease| proteins > amino acids| lipase| lipids  >  fatty acids + glycerol| Amylase is an example of a carbohydrase. Lipids are fats and oils. Different parts of the gut Different parts of the gut produce different enzymes. Where enzymes are produced enzyme| where produced| amylase| salivary glands, pancreas, small intestine| protease| stomach, pancreas, small intestine| ipase| pancreas, small intestine| Summary Overall, this means that: * Amylase catalyses the breakdown of starch into sugars in the mouth and small intestine. * Proteases catalyse the breakdown of proteins into amino acids in the stomach and small intestine. * Lipases catalyse the breakdown of fats and oils into fatty acids and glycerol in the small intestine. Other substances in digestion You should recall that different enzymes work best at different pH values. The digestive enzymes are a good example of this. Enzymes in the stomach The stomach produces hydrochloric acid.

This helps to begin digestion, and it kills many harmful microorganisms that might have been swallowed along with the food. The enzymes in the stomach work best in acidic conditions – in other words, at a low pH. Enzymes in the small intestine After the stomach, food travels to the small intestine. The enzymes in the small intestine work best in alka-line conditions, but the food is acidic after being in the stomach. A substance called bile neutralises the acid to provide the alkaline conditions needed in the small intestine. Bile and enzyme production in the liver and pancreas Enzymes in industry Enzyme names

The names of the different types of enzymes usually end in the letters -ASE. Three of the most common enzymes with their chemical actions are: * lipase – breaks down fats * protease – breaks down proteins * carbohydrase – breaks down carbohydrates Enzyme uses Enzymes allow certain industrial processes to be carried out at normal temperatures and pressures, thereby reducing the amount of energy and expensive equipment needed. Enzymes are also used in the home, for example, in ‘biological’ detergents. The table shows some common enzyme uses you should be familiar with. Uses of enzymes Enzyme| Use| rotease| used to pre-digest proteins during the manufacture of baby foods| lipase| used – together with protease – in biological detergents to break down – digest – the substances in stains into smaller, water soluble substances| carbohydrase| used to convert starch syrup, which is relatively cheap, into sugar syrup, which is more valuable – for example, as an ingredient in sports drinks| isomerase| used to convert glucose syrup into fructose syrup – fructose is sweeter than glucose, so it can be used in smaller amounts in slimming foods| Homeostasis The conditions inside the body must be controlled within narrow limits.

This is called homeostasis. These conditions include water content, ion content, body temperature and blood glucose concentration. The thermoregulatory centre is the part of the brain that monitors and controls body temperature. The pancreas meanwhile monitors and controls blood glucose concentration. It produces a hormone called insulin that reduces blood glucose levels. Diabetes is a disease which can be caused by insufficient insulin. Removing waste products Waste products must be removed from the body. If they are not, they will increase in concentration and may interfere with chemical reactions or damage cells.

Waste products that must be removed include carbon dioxide and urea. Waste product| Why is it produced? | How is it removed? | carbon dioxide| it is a product of aerobic respiration| through the lungs when we breathe out| urea| it is produced in the liver when excess amino acids are broken down| the kidneys remove it from the blood and make urine, which is stored in the bladder temporarily| Production and removal of waste products Water enters the body through food and drink. It is also a product of aerobic respiration in cells. If the amount of water in the body is wrong, cells can be damaged because too much water enters or leaves them.

The pictures show how the amount of water lost as urine is controlled: Controlling blood glucose The pancreas and insulin The pancreas monitors and controls the concentration of glucose in the blood. It produces a hormone called insulin. Insulin causes glucose to move from the blood into cells. It lowers the blood glucose concentration if it has become too high. This can happen after eating a meal that is rich in carbohydrates (for example, sweets, potatoes, bread, rice or pasta). The pictures show how this works. Diabetes Diabetes is a disease where the concentration of glucose in the blood is not controlled properly by the body.

In type 1 diabetes, the pancreas does not produce eno-ugh insulin. This can lead to high levels of glucose in the blood, which can be fatal. Types of Diabetes There are two types of treatment for diabetes: * Careful monitoring of food intake, with particular care taken over carbohydrates – which are digested into glucose. * Injecting insulin into the blood before meals. The extra insulin causes glucose to be taken up by the liver and other tissues. Cells get the glucose they need for respiration, and the blood glucose concentration stays normal. Temperature regulation Human enzymes work best at 37?

C, so the body’s temperature is controlled. A part of the brain called the thermoregulatory centre monitors and controls body temperature. It gathers information as nerve impulses from temperature receptors in: * the brain – these are sensitive to the temperature of the blood flowing there * the skin – these are sensitive to skin temperature Sweating Sweating is one way to help cool the body. We sweat more in hot conditions, so more water is lost from the body. This water must be replaced through food or drink to maintain the balance of water in the body. Ions such as sodium ions and chloride ions are also lost when we sweat.

They must be replaced through food and drink. If the body’s ion content is wrong, cells can be damaged. Temperature regulation – higher If you become too hot or too cold, there are several ways in which your temperature can be controlled. They involve sweating, shivering, skin capillaries and hairs. Too hot When we get too hot: * Sweat glands in the skin release more sweat. This evaporates, removing heat energy from the skin. * Blood vessels leading to the skin capillaries become wider – they dilate – allowing more blood to flow through the skin, and more heat to be lost. Too cold When we get too cold: * Muscles contract rapidly – we shiver.

These contractions need energy from respiration, and some of this is released as heat. * Blood vessels leading to the skin capillaries become narrower – they constrict- letting less blood flow through the skin and conserving heat in the body. The hairs on the skin also help to control body temperature. They lie flat when we are warm, and rise when we are cold. The hairs trap a layer of air above the skin, which helps to insulate the skin against heat loss. Controlling temperature Too cold| Too hot| | | A – Hair muscles pull hairs on end. B – Erect hairs trap air. C – Blood flow in capillaries decreases. | D – Hair muscles relax.

Hairs lie flat so heat can escape. E – Sweat secreted by sweat glands. Cools skin by evaporation. F – Blood flow in capillaries increases. | Remember: Capillaries do not move up and down inside the skin. Temperature is regulated by controlling the amount of blood which flows through the capillaries. Hormones Hormones are chemical substances that help to regulate processes in the body. Hormones are secreted by glands and travel to their target organs in the bloodstream. Several hormones are involved in the female menstrual cycle. Hormones can be used to control human fertility and have advantages and disadvantages. Hormones and glands

Hormones are chemicals secreted by glands in the body. Different hormones affect different target organs. The bloodstream transports hormones from the glands to the target organs. Hormones regulate the functions of many cells and organs The target organ and effects of glands and hormones Gland| Hormone| Target organs| Effect| adrenal gland| adrenalin| vital organs, e. g. liver and heart| Prepares body for action – ‘fight or flight’. | ovary| oestrogen| ovaries, uterus, pituitary gland| Controls puberty and the menstrual cycle in females; stimulates production of LH and suppresses the production of FSH in the pituitary gland. ovary| progesterone| uterus| Maintains the lining of the womb – suppresses FSH production in the pituitary gland. | pancreas| insulin| liver| Controls blood sugar levels. | pituitary gland| anti-diuretic hormone (ADH)| kidney| Controls blood water level by triggering uptake of water in kidneys. | pituitary gland| follicle stimulating hormone (FSH)| ovaries| Triggers egg ripening and oestrogen production in ovaries. | pituitary gland| luteinising hormone (LH)| ovaries| Triggers egg release and progesterone production in ovaries. | testes| testosterone| male reproductive organs| Controls puberty in males. |

Hormones in the menstrual cycle The menstrual cycle in women is a recurring process in which the lining of the uterus – womb – is prepared for pregnancy, and if pregnancy does not happen, the lining is shed at menstruation. Several hormones control this cycle, which includes controlling the release of an egg each month from an ovary, and changing the thickness of the uterus lining. These hormones are secreted by the ovaries and pituitary gland. FSH The hormone FSH is secreted by the pituitary gland. FSH makes two things happen: 1. it causes an egg to mature in an ovary 2. it stimulates the ovaries to release the hormone oestrogen Oestrogen

The hormone oestrogen is secreted by the ovaries. Oestrogen makes two things happen: 1. it stops FSH being produced – so that only one egg matures in a cycle 2. it stimulates the pituitary gland to release the hormone LH LH The hormone LH causes the mature egg to be released from the ovary. This image shows how the level of oestrogen changes during the menstrual cycle. Progesterone is another hormone secreted by ovaries: it maintains the lining of the uterus and stays high during pregnancy. Hormone levels during the menstrual cycle Controlling fertility Human fertility is controlled by hormones.

This means that knowledge of hormones can be used to decide to increase, or reduce, the chances of fertilisation and pregnancy. Oral contraceptives Contraceptive pills The oral contraceptive, ‘the pill’, greatly reduces the chances of mature eggs being produced. The pill contains oestrogen, or oestrogen and progesterone. These hormones inhibit the production of FSH, which in turn stops eggs maturing in the ovaries. Fertility treatment Some women have difficulty becoming pregnant because they don’t produce enough FSH to allow their eggs to mature. ‘Fertility drugs’ contain FSH, which stimulates eggs to mature in the ovary. The nervous system

The nervous system allows the body to respond to changes in the environment. This is a process usually coordinated by the brain. Reflex actions are extra-rapid responses to stimuli, and this process also involves the nervous system, but bypasses the brain. Receptors and effectors Receptors Receptors are groups of specialised cells. They can detect changes in the environment, which are called stimuli, and turn them into electrical impulses. Receptors are often located in the sense organs, such as the ear, eye and skin. Each organ has receptors sensitive to particular kinds of stimulus. Receptors sense organs| receptors sensitive to|

Skin| touch, pressure, pain and temperature| Tongue| chemicals in food| Nose| chemicals in the air| Eyes| light| Ears| sound and position of the head| The central nervous system – CNS – in humans consists of the brain and spinal cord. When a receptor is stimulated, it sends a signal along the nerve cells – neurones – to the brain. The brain, then co-ordinates the response. Effectors An effector is any part of the body that produces the response. Here are some examples of effectors: * a muscle contracting to move the arm * a muscle squeezing saliva from the salivary gland * a gland releasing a hormone into the blood Neurones

Neurones are nerve cells. They carry information as tiny electrical signals. There are three different types of neurones, each with a slightly different function. 1. Sensory neurons carry signals from receptors to the spinal cord and brain. 2. Relay neurons carry messages from one part of the CNS to another. 3. Motor neurons carry signals from the CNS to effectors. The diagram below shows a typical neuron – in this case, a motor neuron. It has tiny branches at each end and a long fibre carries the signals. A motor neuron Synapses Where two neurones meet, there is a tiny gap called a synapse. Signals cross this gap using chemicals.

One neurone releases the chemical into the gap. The chemical diffuses across the gap and makes the next neurone transmit an electrical signal. Reflex actions When a receptor is stimulated, it sends a signal to the central nervous system, where the brain co-ordinates the response. But sometimes a very quick response is needed, one that does not need the involvement of the brain. This is a reflex action. Reflex actions are rapid and happen without us thinking. For example, you would pull your hand away from a hot flame without thinking about it. The animation below allows you to step through each stage of the reflex arc.

This is what happens: 1. receptor detects a stimulus – change in the environment 2. sensory neurone sends signal to relay neurone 3. motor neurone sends signal to effector 4. effector produces a response The way the iris in our eye adjusts the size of the pupil in response to bright or dim light is also a reflex action. In bright light: * Radial muscles of the iris relax. * Circular muscles of the iris contract. * Less light enters the eye through the contracted pupil. In dim light: * Radial muscles of the iris contract. * Circular muscles of the iris relax. * More light enters the eye through the dilated pupil.

Defending against infection Pathogens are microorganisms – such as bacteria and viruses – that cause disease. Bacteria release toxins, and viruses damage our cells. White blood cells can ingest and destroy pathogens. They can produce antibodies to destroy pathogens, and antitoxins to neutralize toxins. In vaccination pathogens are introduced into the body in a weakened form. The process causes the body to produce enough white blood cells to protect itself against the pathogens, while not getting diseased. Antibiotics are effective against bacteria, but not against viruses. Some strains of bacteria are resistant to antibiotics.

Pathogens – bacteria Pathogens are microorganisms that cause infectious disease. Bacteria and viruses are the main pathogens. Bacteria Bacteria are microscopic organ-isms. They come in many shapes and sizes, but even the largest are only 10 micrometres long – 10 millionths of a metre. Bacteria are living cells and, in favourable conditions, can multiply rapidly. Once inside the body, they release poisons or toxins that make us feel ill. Diseases caused by bacteria include:- -food poisoning -cholera -typhoid -whooping cough -gonorrhoea – a sexually transmitted disease Pathogens – viruses Viruses are many times smaller than bacteria.

They are among the smallest organisms known and consist of a fragment of genetic material inside a protective protein coat. Viruses can only reproduce inside host cells, and they damage the cell when they do this. A virus can get inside a cell and, once there, take over and make hundreds of thousands of copies of itself. Eventually the virus copies fill the whole host cell and burst it open. The viruses are then passed out in the bloodstream, the airways, or by other routes. Diseases caused by viruses include: * influenza – flu * colds * measles * mumps * rubella * chicken pox * AIDS White blood cells

The body has different ways of protecting itself against pathogens. The first defence is passive immunity. This is aimed at stopping the pathogen getting into the body in the first place. The body’s passive immunity system includes the skin, mucus and cilia in the respiratory system, acid in the stomach, and enzymes in tears. If a pathogen still manages to get into the body, the second defence takes over. This is called active immunity, and the white blood cells have key functions in this. Functions of the white blood cells White blood cells can: * ingest pathogens and destroy them * produce antibodies to destroy pathogens produce antitoxins that neutralise the toxins released by pathogens In a written examination, it is easy to get carried away and waffle on about things such as invaders and battles, but stick to the point. Note that: * the pathogens are not the disease – they cause the disease * white blood cells do not eat the pathogens – they ingest them * antibodies and antitoxins are not living things – they are specialised proteins More about white blood cells There are several different types of white blood cells, each with different functions, but they can be put into two main groups: * phagocytes or macrophages lymphocytes Phagocytes Phagocytes can easily pass through blood vessel walls into the surrounding tissue and move towards pathogens or  toxins. They then either: * ingest and absorb the pathogens or toxins * release an enzyme to destroy them Having absorbed a pathogen, the phagocytes may also send out chemical messages that help nearby lymphocytes to identify the type of antibody needed to neutralise them. Lymphocytes Pathogens contain certain chemicals that are foreign to the body and are called antigens. Each lymphocyte carries a specific type of antibody – a protein that has a chemical ‘fit’ to a certain antigen.

When a lymphocyte with the appropriate antibody meets the antigen, the lymphocyte reproduces quickly, and makes many copies of the antibody that neutralises the pathogen. Antibodies neutralise pathogens in a number of ways: * they bind to pathogens and damage or destroy them * they coat pathogens, clumping them together so that they are easily ingested by phagocytes * they bind to the pathogens and release chemical signals to attract more phagocytes Lymphocytes may also release antitoxins that stick to the appropriate toxin and stop it damaging the body. Vaccination People can be immunised against a pathogen through vaccination.

Different vaccines are needed for diffe-rent pathogens. Vaccination involves putting a small amount of an inactive form of a pathogen, or dead pathogen, into the body. Vaccines can contain: * live pathogens treated to make them harmless * harmless fragments of the pathogen * toxins produced by pathogens * dead pathogens These all act as antigens. When injected into the body, they stimulate white blood cells to produce antibodies against the pathogen. Because the vaccine contains only a weakened or harmless version of a pathogen, the vaccinated person is not in danger of developing disease – although some people may uffer a mild reaction. If the person does get infected by the pathogen later, the required lymphocytes are able to reproduce rapidly and destroy it. Vaccines and boosters Vaccines in early childhood can give protection against many serious diseases. Sometimes more than one vaccine is given at a time, like the MMR triple vaccine against mumps, measles and rubella. Sometimes vaccine boosters are needed, because the immune response ‘memory’ weakens over time. Anti-tetanus injections may need to be repeated every ten years. Antibiotics Antibiotics are substances that kill bacteria or stop their growth.

They do not work against viruses: it is difficult to develop drugs that kill viruses without also damaging the body’s tissues. How some common antibiotics work antibiotic| how it works| penicillin| breaks down cell walls| erythromycin| stops protein synthesis| neomycin| stops protein synthesis| vancomycin| stops protein synthesis| ciprofloxacin| stops DNA replication| Penicillin The first antibiotic – penicillin – was discovered in 1928 by Alexander Fleming. He noticed that some bacteria he had left in a petri dish had been killed by naturally occurring penicillium mould.

Since the discovery of penicillin, many other antibiotics have been discovered or developed. Most antibiotics used in medicine have been altered chemically to make them more effective and safer for humans. Resistance Bacterial strains can develop resistance to antibiotics. This happens because of natural selection. In a large population of bacteria, there may be some cells that are not affected by the antibiotic. These cells survive and reproduce, producing even more bacteria that are not affected by the antibiotic. MRSA is methicillin-resistant staphylococcus aureus.

It is very dangerous because it is resistant to most antibiotics. It is important to avoid over-use of antibiotics, so we can slow down, or stop, the development of other strains of resistant bacteria. Cleanliness One simple way to reduce the risk of infection is to maintain personal hygiene and to keep hospitals clean. Diet and Exercise Regular exercise and a balanced diet are needed to keep the body healthy. Too little food leads to a person being underweight and prone to illness, while too much food and not enough exercise leads to a person being overweight and prone to other illnesses.

Excess cholesterol increases the risk of heart disease, and excess salt causes high blood pressure and increases the risk of heart disease and stroke. Nutrients A mixture of different types of food in the correct amounts is needed to maintain health. The main food groups are: The main food groups food group| found in| required by our bodies for| | potatoes, pasta, bread, bananas, sugar and rice| A source of energy for other life processes. Sometimes referred to as fibre, which is actually just one – very common – type of carbohydrate. | | cheese, butter, margarine and oils| Fats are needed to make cell membranes and to insulate our bodies.

They also contain important fat-soluble vitamins. | | meat, fish, eggs and cheese| Growth and repair. | | whole meal bread, fruit, vegetables and pulses| The fibre or roughage in our diet is not digested, but is important because it allows the muscles in our intestines to move food through our system by peristalsis. | Metabolic rate A healthy diet contains all the different nutrients in the correct amounts, and provides the right amount of energy for each individual. An unbalanced diet can lead to a person becoming malnourished. They may be too thin or too fat as a result, and they may suffer from deficiency diseases.

Chemical reactions Respiration is the chemical reaction that allows cells to release energy from food. The metabolic rate is the speed at which such chemical reactions take place in the body. It varies because of several factors, including: * age * gender – male or female * the proportion of muscle to fat in the body * the amount of exercise and other physical activity * genetic traits The metabolic rate increases as we exercise and stays high for a while afterwards. The right amount of food Not enough food If you don’t eat enough food, you will become too thin and may suffer from health problems.

These include: * irregular periods in women * reduced resistance to infection * deficiency diseases Deficiency diseases include rickets – which affects proper growth of the skeleton and is caused by insufficient vitamin D – and kwashiorkor – which causes a swollen abdomen and is a result of insufficient protein. Problems such as these are more likely to affect people in the developing world, where it can be more difficult to get enough food. Too much food In warm weather, or when you don’t do much exercise, you do not need to eat as much food as when it is cold or when you have exerted yourself physically.

If you eat too much food without taking enough exercise, you will become overweight. Very fat people are described as obese. Overweight people may suffer from health problems, including: * diabetes – an illness in which the body is unable to control the amount of sugar in the blood * arthritis – an illness in which the joints become worn, inflamed and painful * high blood pressure * heart disease The heart The heart is an organ that needs its own supply of blood to keep it working. If the blood supply is reduced, the heart muscle will not work properly and will become weaker.

A heart attack happens when part of the heart does not get any blood because of a blocked artery. Cholesterol Cholesterol is a substance found in the blood. It is made in the liver and is needed for healthy cell membranes. However, too much cholesterol in the blood increases the risk of heart disease, and of diseased arteries. Good and bad cholesterol The bloodstream transports cholesterol around the body attached to proteins. The combination of cholesterol and protein is called lipoprotein, and there are two types. 1. Low-density lipoproteins – LDLs – carry cholesterol from the liver to the cells. 2.

High-density lipoproteins – HDLs – carry excess cholesterol back to the liver. LDLs are often called ‘bad’ cholesterol because they lead to fat building up on artery walls, which causes heart disease. HDLs are often called ‘good’ cholesterol because they help to stop fat building up in the arteries. Improving the balance A high proportion of HDLs to LDLs is good for a healthy heart. Monounsaturated and polyunsaturated oils – as found in vegetable oils – help to reduce cholesterol levels in the blood, and also increase the proportion of HDLs compared with LDLs. Check your understanding of such oils by looking at Vegetable oils.

There are also drugs that can improve high blood pressure and high cholesterol levels. Salt Table salt is sodium chloride. Too much salt in the diet can lead to high blood pressure, which in turn leads to an increased risk of heart disease and strokes. Salt is found naturally in many kinds of food, but more is added by food manufacturers – and many people add even more when they are eating. Processed foods often have a high proportion of salt and fat. Salt added to food during processing accounts for about two-thirds of the average salt intake. Adaptation Adaptations – cold climates

Every organism has certain features or characteristics that allow it to live successfully in its habitat. These features are called adaptations, and we say that the organism is adapted to its habitat. Organisms living in different habitats need different adaptations. The polar bear Polar bears are well adapted for survival in the Arctic. They have: * a white appearance, as camouflage from prey on the snow and ice * thick layers of fat and fur, for insulation against the cold * a small surface area to volume ratio, to minimise heat loss * a greasy coat, which sheds water after swimming

The snowshoe hare The snowshoe hare has white fur in the winter and reddish-brown fur in the summer. This means that it is camouflaged from its predators for most of the year. Arctic plants The Arctic is cold and windy with very little rainfall. Plants in the Arctic often grow very close to the ground and have small leaves. This helps to conserve water and to avoid damage by the wind. Adaptations – hot climates The camel Camels live in deserts that are hot and dry during the day, but cold at night. They are well adapted for survival in the desert.

Camels have: * Large, flat feet to spread their weight on the sand. * Thick fur on the top of the body for shade, and thin fur elsewhere to allow easy heat loss. * A large surface area to volume ratio to maximise heat loss. * The ability to go for a long time without water (they don’t store water in their humps, but they lose very little through urination and sweating). * The ability to tolerate body temperaturesup to 42°C. * Slit-like nostrils and two rows of eyelashesto help keep the sand out. Desert plants Cacti are well adapted for survival in the desert. They have: * Stems that can store water. Widespread root systems that can collect water from a large area. In addition, cacti have spines instead of leaves. These minimise the surface area and so reduce water loss by transpiration. The spines also protect the cacti from animals that might eat them. Other adaptations Animals and plants may have specific features that adapt them to their environment. These include barbs and spines, poisons and warning colours that deter predators and herbivores. Some harmless species may even resemble a poisonous or dangerous species to increase their chances of survival. Characteristics and classification

Genetic information from one species can be transferred to another species using genetic engineering. Selective breeding, also called artificial selection, involves people taking charge of selection to produce new varieties of various species. A variety is a type of a particular species that is different in some clear way from other varieties of that species. The characteristics of a species can be used to classify the species. This is sometimes difficult to do. Genetic engineering Genetic engineering is also called genetic modification (or GM). It is not the same as cloning.

Although cloning techniques are used in genetic engineering, the two things should not be confused. The table shows some of the differences. Cloning| Genetic engineering| Produces exact copies. | Produces a unique set of genes. | Genes copied within the same species. | Genes can be swapped across species. | Selective breeding Natural selection Species gradually evolve by a process of natural selection. The individuals in any population with the inherited features best suited to the environment in which they live are most likely to survive and reproduce. When they do, they pass on the genetic information for these features to their offspring.

Over time, a species can change its appearance and may even become a new species, unable to reproduce successfully with individuals of the original species. Artificial selection Selective breeding, also called artificial selection, involves people taking charge of selection to produce new ‘varieties’ of various species. A variety is a type of a particular species that is different in some clear way from other varieties of that species. For example, pedigree dogs come in lots of different varieties (or breeds) – they may be different colours and sizes, but they are all still dogs.

Suppose you wanted a variety of cow that produced a lot of milk. This is what you could do: * choose or select the cows in your herd that produce the most milk * only let these cows reproduce * select the offspring that produce the most milk * only let these offspring reproduce * keep repeating the process of selection and breeding until you achieve your goal The key here is to identify the feature you want, and only breed from the individuals that have that feature. Here are some examples of what selective breeding can produce: * hens that lay big eggs of a particular colour cattle that produce lots of meat * tomato plants that produce lots of tomatoes * crops that are resistant to certain plant diseases Changing the characteristics of a species The characteristics of a species can be changed by: * natural selection * selective breeding * genetic engineering. The table shows some differences between these. | Natural selection| Selective breeding| Genetic engineering| Number of generations needed for change| very many| many| one| Human intervention| not needed| needed| needed| Desired outcome known? | no| yes| yes| New species formed? | yes| no| no|

Notes| This is the mechanism of change in Darwin’s theory of evolution| This is how new varieties or breeds are usually produced| Genetic information can come from the same species or from a different one| In selective breeding and genetic engineering, there is a goal or desired outcome. For example, we may wish to produce a variety of cow capable of producing a lot of milk, or a bacterium capable of producing insulin. There is no goal in natural selection: although we find that particular species are well adapted to their environments, natural selection does not ‘know’ what the species should be like.

Individuals that are better suited to their environment are more likely to survive to reproduce, and so pass on their characteristics to the next generation, than those that are poorly suited. Classification You will remember from your Key Stage 3 studies that species with similar characteristics are put into groups, and that this is called classification. Remind yourself of the basics of classification by looking here. Kingdoms The first rank in this system is called a kingdom. There are five kingdoms, based upon what an organism’s cells are like: 1. nimals (all multicellular animals) 2. plants (all green plants) 3. fungi (moulds, mushrooms, yeast) 4. prokaryotes (bacteria, blue-green algae) 5. protoctists (Amoeba, Paramecium) Further divisions There are several further ranks before we reach a particular species. In order, these are: * kingdom * phylum * class * order * family * genus * species For example, lions have the following classification: * kingdom – animal * phylum – vertebrate * class – mammal * order – carniverous * family – cat * genus – big cat * species – lion Difficulties with classification

It can be easy to classify a species. For example, we are Homo sapiens. Classification of species rank| classification| notes| kingdom| animals|  | phylum| chordates| animals with backbones| class| mammals| animals that are warm-blooded, have lungs and body hair, produce milk and give birth to live young| order| primates| ape-like animals| family| hominids| human-like animals| genus| homo| humans| species| sapiens| modern humans| It can also be difficult to classify a certain organism. For example, the single-celled organism called Euglena has some confusing characteristics.

It has: * chloroplasts, like a plant * no cell wall, like an animal * a flagellum to swim with, like some bacteria A fifth kingdom, called the protoctists, was made for organisms like Euglena. The Heart The heart requires its own constant blood supply in order to keep beating and this is delivered through the coronary arteries. Genetic and lifestyle factors can lead to the coronary arteries becoming blocked, and an increased risk of heart disease. The circulatory system Blood carries oxygen and nutrients to the body’s cells, and waste products away from them.

The circulatory system consists of: * the heart, which is the muscular pump that keeps the blood moving * the arteries, which carry blood away from the heart * the veins, which return blood to the heart * the capillaries, which are tiny blood vessels that are close to the body’s cells The diagram outlines the circu-latory system. To make things clear, oxygenated blood is shown in red, and deoxygenated blood in blue. Arteries and veins The arteries carry blood from the heart, while veins return blood to it. With both, their structure is related to their function. Arteries

Blood in the arteries is under high pressure generated by the heart. The arteries have: * thick outer walls * thick layers of muscle and elastic fibres Veins The blood in veins is under lower pressure than the blood in arteries. The veins have: * thin walls * thin layers of muscle and elastic fibres Unlike arteries, veins have one-way valves in them to keep the blood moving in the correct direction. The heart The heart is a muscular organ. It keeps beating at about 70 times per minute. You can see how it pumps the blood to the lungs and the rest of the body by studying this animation.

The muscle cells in the heart need a constant supply of oxygen and nutrients, and for their waste products to be removed. So the heart requires its own blood supply in order to keep beating. Blood vessels called the coronary arteries supply blood to the heart muscles. If they become blocked, a heart attack can happen. Heart attacks A heart attack can happen because: 1. Fatty deposits build up in the coronary arteries. 2. A blood clot can form on a fatty deposit. 3. The blood clot can block a coronary artery. 4. Some heart muscle cells do not get the oxygen and nutrients they need. 5. These cells start to die.

Causes of heart disease Heart disease is not usually caused by micro-organisms. It is caused by: * genetic factors, which show as a family history of heart disease * lifestyle factors Heart disease is more common in the UK than in non-industrialised countries, and many other indust-rialised nations. This is due to lifestyle factors including: * smoking * lack of regular exercise * stress leading to a fast heart rate * drinking a lot of alcohol * poor diet A lack of exercise and a diet that is high in salt and saturated fat cause people to: * become overweight * have high blood pressure have high levels of cholesterol in their blood These factors contribute to an increased risk of heart disease. Extra Sex hormones Changes occur at puberty because of sex hormones produced by the testes in boys, and the ovaries in girls. Some changes happen to everyone, both boys and girls, while others happen in one sex only. Here are some changes that happen to both boys and girls: * pubic hair grows * underarm hair grows Here are some changes that happen to boys only: * voice breaks – gets deeper * hair grows on face and body * body becomes more muscular * testes and penis get bigger testes start to produce sperm cells Here are some changes that happen to girls only: * hips get wider * breasts develop * ovaries start to release egg cells – periods start Fertility in humans can be controlled by the artificial use of sex hormones, including contraceptive pills and fertility drugs. Competition Different species compete to survive and breed. The size of a predator population depends on the size of the prey population, and the reverse is true as well. Mutualism benefits both species involved in the relationship, but parasitism only benefits the parasite, not the host.

Habitats have limited amounts of the resources needed by living organisms. Organisms must compete with others in order to get enough of these resources to survive. If they are unsuccessful and cannot move to another habitat, they will die. Animals Some of the resources that animals compete for: * food * water * space Animals may also compete for mates so that they can reproduce. Plants Remember that plants make their own food using photo-synthesis, so they do not compete for food. Here are some of the things that plants do compete for: * light * water space * mineral salts Human beings Human beings are very successful organisms. We compete with animals for food resources, and we compete with both animals and plants for space and water. The nitrogen cycle Seventy-nine per cent of the air around us is nitrogen. Living things need nitrogen to make proteins, but they cannot get it directly from the air because nitrogen gas is too unreactive to be used to make new compounds within an organism. Plants can take up and use nitrogen when it is in a more reactive form – for example, in nitrates or ammonium salts.

Changing nitrogen into a more reactive substance is called nitrogen fixation. Nitrogen fixation Nitrogen fixation happens in three different ways: The energy in a lightning bolt can split nitrogen molecules in the air, allowing each nitrogen atom to react with oxygen to form nitrogen oxides. The rain washes these oxides to the ground, where they form nitrates. * The Haber Process is used by industry to produce ammonia from nitrogen. Ammonia is then used to make the fertiliser that farmers spread on the soil to feed their crops. Nitrogen-fixing bacteria found in both the soil and root nodules of leguminous plants fix nitrogen into a form that can be used by plants. When plants are eaten by animals, the nitrogen compounds are passed on. Nitrogen compounds are returned to the soil by excretion and egestion from animals, or when plants and animals die and decay. The nitrogen compounds returned in this way are changed back to nitrogen gas by denitrifying bacteria which live in the soil. This completes the cycle, so that the percentage of nitrogen in the air remains constant. The nitrogen cycle

Free Essays

Learning and Memory: Biology vs. Society

There has been much debate about the nature of human’s intelligence.  Questions arise from the matter.  Is the way you think and learn inherited, or as the nature side of the debate argues, biological?  Or is the way you think influenced by outside forces, or as the nature side of the debate argues, societal?  This paper aims to present the points of view of each side of the argument.  At the end of the paper, the author gives not just a summary of what has been presented but also an integration of the two views that gives the more believed perspective nowadays.  From this point on, the society that is referred to in the title is the environmental factors and biology is the genetic factors.

During the last twenty years, genetics has moved from a relatively difficult to understand sub-field of biology to one of its most well funded segments.  Over these twenty years, there has been an explosion of genetic discoveries.  Nevertheless, more and more questions pop out from our minds regarding genetics.  One of these is the question: How does genetics research fit with our existing notions of us as humans?

Recently, there have been an increasing number of researches that prove that cognitive abilities such as learning and memorizing are determined by genes.  That is, that our intelligence is hereditary.  Our human knowledge and cognitive processes are passed on from our parents.  Nature theorists believe that our cognitive abilities are the product of “a unique web of interactions among genes” (Lickliter and Honeycutt 461).

These nature theorists believe that when we were born, our intelligence and everything that we know of are already part of ourselves because of our genes.  That is, they believe that “Nature is everything, nurture nothing” (Gopnik).  Leamnson and Betz (as cited in McMahon) argue that learning is a biological process as much as respiration or circulation is.  McMahon further explains that cognitive abilities such as thinking, learning and memorizing take place when biochemical reactions occur across synapses which then form the neural networks.

While some researchers agree to the fact that genetic and environmental factors both play an important part in our cognitive development, they still believe that genes take the primary part in influencing our thinking, learning and memorizing abilities.  In their study, Genetic and Environmental Influences on the Development of Intelligence, Bartels et al. found that as the child grows up, the genetic influence on his intelligence increases while environmental factors decrease influence to his cognitive ability.  Thus, they conclude that “genetic influences are the main driving force behind continuity in general cognitive ability” (Bartels et al. 247).

On the other side of the debate are the nurture theorists.  These theorists believe that environmental factors have a more significant part in sharpening our cognitive processes.  These nurture theorists believe in John Locke’s philosophy that when we were born, our minds are in blank states or as they call it tabula rasa. That is, when we were born, we do not know anything.  We only acquire knowledge, that is, we only learn as we experience the world around us.  That is, as Gopnik puts it, “nurture is everything, nature nothing.”  Locke believed that we learn through experience.

James Flynn, a NZ-based political scientist, found that after World War II, the average IQ in all countries increased which he claims is due to environmental effects.  Ulric Neisser explains further that this is because children are increasingly exposed to sophisticated visual images such as ads, posters, videogame and television in contrast to the methods of learning before the world war.  This suggests that the children’s cognitive abilities are influenced by the environment (Gopnik).

Recently, however, there are an increasing number of researchers who believe that intelligence is influenced by both genetics and environmental factors.  There is no dominant factor; both play an equal role in the development of human intelligence.  Lickliter and Honeycutt describe the developmental systems theory (DST) that believes in the power of both genetics and environment to influence our cognitive abilities.  According to this theory, our cognitive abilities cannot be determined by genetics or environmental factors alone.

As Lickliter and Honeycutt explain, “development is seen as a self-organizing…process in which pattern and order emerge and change as a result of complex interactions and relations among developmentally relevant resources both internal (including genes, but also cells, hormones, organs) and external to the organism (and not from some set of prespecified instructions)” (Lickliter and Honeycutt 462).  In contrast to the solely nature theorists, DST argues that genes and the mere passing of it to a child is not a sufficient explanation or cause of an individual’s learning and memorizing.  That is, although genes and environment both play an important role to the cognitive development of human beings, we cannot separate them and consider them as independent causes.

The nature vs. nurture debate is likely to continue on but unlikely to be resolved to the satisfaction of those who strictly believe that intelligence is solely nature caused or nurture caused.  However, recently both environmentalists and behavior geneticists have called for the matter to have be ended by echoing Anastasi’s call to emphasize more on the question “How?” rather than “How much?” in the study of heredity and environment.

Works Cited:

“Nature Vs. Nurture in Intelligence”.  2005. November 20 2007. <>.

Bartels, M., et al. “Genetic and Environmental Influences on the Development of Intelligence.” Behavior Genetics 32 (2002): 237-49.

Gopnik, Alison. Nature vs. Nurture. 2004.

Lickliter, Robert, and Hunter Honeycutt. “Evolutionary Approaches to Cognitive Development: Status and Strategy.” Journal of Cognition and Development 4 (2003): 459-73.

McMahon, Graham Peter. “Getting the Hots with What’s in the Box: Developing Higher Order Thinking Skills within a Technology-Rich Learning Environment.” Curtin University of Technology, 2007.


Free Essays

Biology Midterm

Midterm Study Guide Answers 1. A hypothesis is an explanation of observations. “If the floor is wet, I will slip. ” 2. A controlled experiment is when only one variable is changed. 3. If the plant you are experimenting with has a disease that is an unavoidable experimental error. 4. An enzyme speeds up reactions and lowers the energy it takes to produce something, a lock and key. 5. Autotrophs make their own food by producing sugars from sunlight and various chemicals. 6. Abiotic factors are factor that are nonliving, such as the air, sunlight and the temperature. Biotic factors are living factors like birds, trees and fish. . Primary succession- occurs on surfaces where no soil exists. 8. 9. If there are too many predators and not enough prey then the predator will eventually die off. Then the prey’s population will increase. 10. Non-native species can kill native species because they aren’t familiar with the new organisms. 11. The SUN! 12. Producer because they use the suns energy. 13. When heat gets trapped in the ozone layer. 14. Eukaryotes have a nucleus with genetic information inside them and are more complex than prokaryotes which have free floating genetic information and no nucleus. 5. Nucleus has DNA Mitochondria- converts chemical energy into usable compounds Ribosomes- assembles proteins Chloroplast-converts sun’s energy into chemical energy and is only found in plants 16. Osmosis 17. ATP- stores and releases energy by breaking polypeptide bonds. 18. Photosynthesis releases energy, sugars, into plants. It takes place inside of the chloroplast and it uses water and CO2 to produce oxygen and sugars. 19. 6CO2+6H2O and light sugars+oxygen Carbon dioxide + water and Light sugars + oxygen 20. Cellular Respiration releases energy into living things.

It happens inside of the mitochondria and uses glucose, sugars from foods, to make ATP, energy. 21. Glucose is broken down in glycolysis for cellular respiration. 6O2+C6H12O6 and Light 6CO2 + 6H2O +Energy 22. Meiosis is when the number of chromosomes per cell is cut in half through separating homologous chromosomes in a diploid cell. We need meiosis for making haploid cells from diploid cells. The difference between mitosis and meiosis is mitosis makes two genetically identical diploid cells while meiosis produces four genetically different haploid cells. 23. Cancer is when our bodies can’t control the growth of cells. 4. 25. The two main sources of variability are mutations and selective breeding. 26. Before a cell divides it copies its DNA. 27. Allele- one of a number of different forms of a gene Diploid- a cell that contains both sets of homologous chromosomes Haploid- cell that contains a single set of chromosomes and only a single set of genes 28. The offspring from these parents would either be homozygous dominant of heterozygous. 29. The possible genotypes would be BB, Bb and bb. 30. YY or Yy 31. The structure of DNA looks like a twisted ladder or a double helix and it was discovered by Watson and Crick. 2. The subunits of a DNA molecule are similar to the rungs on a ladder and they are made up of a phosphate group, sugar and a nitrogenous base. 33. RNA is different from DNA in many ways, many is the RNA has the sugar ribose instead of deoxyribose. Also, DNA is double stranded while RNA only has one strand and RNA has the nitrogenous base uracil compared to DNA’s thymine. 34. AATCGGACTG 35. During DNA replication, DNA separates into two strands and bonds complementary nitrogenous bases together with DNA polymerase. This produces two semiconservative DNA molecules. 36.

A codon is three nucleotides that specify an amino acid in a polypeptide chain. 37. AUG codes for the amino acid methionine and you can tell by using the genetic code. 38. Transcription uses RNA polymerase that bonds together a separated piece of DNA with a strand of RNA. 39. When the cell uses information from mRNA to make proteins is called translation. 40. mRNA- to carry copies of instructions for assembling amino acids rRNA- made up of ribosomes tRNA- transfers amino acids to the ribosome specified by coded messages in mRNA 41. Recombinant DNA is DNA that is made by combining tow DNA’s from different sources. 2. Selective Breeding is like breeding certain dogs together to make the healthiest and best looking puppies. 43. In biotechnology scientists use gel electrophoresis and restriction enzymes to cut and separate DNA fragments. 44. Chromosomes determine an organisms sex by men have an X and a Y while women have two X’s. 45. Men are more likely to be colorblind because it is a sex-linked on the X axis. Also in women, since we have two X’s, we have a chance to cover up this gene with a dominant gene but men cannot because they only have one X gene.

Free Essays

Biology Chapter 19

1. Viruses can vary with respect to all of the following characteristics except _____. ( Overview) Your Answer:| the presence or absence of a membranous envelope | | Correct Answer:| the presence or absence of metabolic machinery | |   No. This is a difference among viruses. 2. A microbiologist analyzes chemicals obtained from an enveloped RNA virus that infects monkeys. He finds that the viral envelope contains a protein characteristic of monkey cells. Which of the following is the most likely explanation? ( Concept 19. 1) Your Answer:| Its presence is a result of the monkey’s immunological response. | Correct Answer:| The viral envelope forms as the virus leaves the host cell. | |   No. This does not explain the presence of either the envelope or the monkey protein found on the envelope. 3. Which of the following, if any, may be a component of a virus? ( Concept 19. 1) Your Answer:| single-stranded (ss) RNA | | Correct Answer:| All of the listed responses are correct. | |   No. Single-stranded RNA is the genetic material of certain viruses, but there is a better answer. 4. Viruses that infect bacteria are called _____. ( Concept 19. 1) Your Answer:| capsomeres | | Correct Answer:| bacteriophages | |

No. Capsomeres are the protein subunits of the capsid, the protein shell that encloses the viral genome. 5. HIV, the virus that causes AIDS, only infects certain cells within the immune system. This is because _____. ( Concept 19. 2) Your Answer:| other cells produce toxins that destroy the virus before infection can take place | | Correct Answer:| the virus binds to specific receptors that are only present on certain immune cells | |   No. This is not true. 6. Cancer cells often have protein receptor molecules on their surfaces that differ from those on normal body cells.

Given this fact, how might viruses be used to treat cancer? ( Concept 19. 2) Your Answer:| Viruses could be engineered to infect only cancer cells by altering viral surface proteins to recognize only the receptors on cancer cells. |   Correct. The host specificity of viruses could be used to make cancer cells “sick” whereas normal body cells would not be infected. This approach would reduce the collateral damage seen in chemotherapy. 7. Why are phages useful in treating bacterial infections in humans? ( Concept 19. 2) Your Answer:| Because of their host specificity, they only attack bacteria.

They do not affect eukaryotic cells. | | Correct Answer:| The first three answers are correct. | |   No. This is true, but there is a better answer. 8. Which of the following can a virus do without a host cell? ( Concept 19. 2) Your Answer:| transcribe DNA | | Correct Answer:| None of the listed responses is correct. | |   No. DNA viruses use the RNA polymerase of the host to transcribe viral DNA. 9. When a virus infects an E. coli cell, what part of the virus enters the bacterial cytoplasm? ( Concept 19. 2) Your Answer:| the tail fibers | | Correct Answer:| only the nucleic acid | | No.

The tail remains outside the host cell. 10. The phage reproductive cycle that kills the bacterial host cell is a _____ cycle, and a phage that always reproduces this way is a _____ phage. ( Concept 19. 2) Your Answer:| lysogenic … virulent | | Correct Answer:| lytic … virulent | | No. A virus with a lysogenic cycle is a temperate virus. 11. In the lytic life cycle of phages _____. ( Concept 19. 2) Your Answer:| the viral capsid is assembled according to the genetic information of the bacterium | | Correct Answer:| the cell typically dies, releasing many copies of the virus | |   No.

The viral capsid assembles spontaneously from its subunits, the capsomeres. 12. Restriction enzymes help defend bacteria against viral infections by _____. ( Concept 19. 2) Your Answer:| cutting viral DNA once it has entered the cell |   Correct. Restriction enzymes cut viral DNA, but bacterial DNA is modified in such a way as to protect it against the enzymes. 13. A phage that inserts itself into the host DNA is called _____. ( Concept 19. 2) Your Answer:| a capsomere | | Correct Answer:| lysogenic | | No. Capsomeres are the protein subunits of capsids. 14. A prophage is a(n) _____. Concept 19. 2) Your Answer:| virus that infects bacteria | | Correct Answer:| viral genome that has been incorporated into a bacterial cell’s chromosome | |   No. This type of virus is called a bacteriophage. 15. In the lysogenic cycle of phages _____. ( Concept 19. 2) Your Answer:| the viral nucleic acid inserts itself into the host chromosome | | Correct Answer:| All of the listed responses are correct. | |   No. This statement is true, but it is not the best response. 16. What is the origin of the phospholipid membrane that envelops many animal viruses? ( Concept 19. ) Your Answer:| It is “stolen” from the host cell, but it contains some proteins encoded by the viral genome. |   Correct. Newly formed viruses “cloak” themselves in phospholipid membrane derived from the host, but certain components encoded by the viral genome are also included in the envelope. 17. Why can flare-ups of herpesvirus infection recur throughout a person’s life? ( Concept 19. 2) Your Answer:| Herpesvirus may cloak itself in a cell’s nuclear envelope, making it very difficult for the immune system to recognize it. | | Correct Answer:| Herpesvirus can leave its DNA behind as minichromosomes in nerve cell nuclei.

Stress can trigger another round of virus production, producing characteristic blisters and sores. | |   No. Herpesvirus does use the nuclear envelope’s membrane as its envelope at some times, but recurrences are caused by the virus leaving its DNA in the nucleus of certain nerve cells. When triggered, the viral DNA can set off another round of virus production. 18. How do retroviruses, such as HIV, differ from other viruses? ( Concept 19. 2) Your Answer:| They contain DNA that is used as a template to make RNA. | | Correct Answer:| They can transcribe a DNA copy from a RNA template. | |   No.

Retroviruses are not DNA viruses. 19. Reverse transcription, carried out by retroviruses, is the process by which _____. ( Concept 19. 2) Your Answer:| RNA information is “read” to form a protein molecule | | Correct Answer:| RNA information is copied into DNA | | No. This is translation. 20. Which statement below is a correct comparison of a “regular” RNA virus and an RNA retrovirus? ( Concept 19. 2) Your Answer:| Only the RNA retrovirus performs translation. | | Correct Answer:| Both produce protein coats via translation of mRNA. | |   No. Translation is required for the manufacture of viral proteins. 1. When comparing DNA and RNA viruses, which mutate more quickly, and why? ( Concept 19. 2) Your Answer:| RNA viruses, because RNA is single-stranded and thus more prone to mutations | | Correct Answer:| RNA viruses, because no proofreading is done on RNA molecules | |   No. RNA viruses mutate more quickly because RNA molecules are not proofread. 22. The symptoms of a viral infection in a person can be caused by _____. ( Concept 19. 3) Your Answer:| the reaction of the individual’s immune system to the infection | | Correct Answer:| All of the listed responses are correct. | |   No.

This statement is true, but there is a better response. 23. Vaccines for viral diseases are _____ and help prevent infection by _____. ( Concept 19. 3) Your Answer:| protease inhibitors … preventing synthesis of envelope proteins | | Correct Answer:| harmless derivatives of pathogenic viruses … stimulating the immune system to mount a defense against the actual pathogen | |   No. Protease inhibitors are not vaccines but are instead a separate class of antiviral drugs. 24. Emerging viruses can originate from which of the following sources? ( Concept 19. 3) Your Answer:| animal viruses | |

Correct Answer:| All of the listed responses are correct. | |   No. This is a possible source, but there is a better answer. 25. What is the function of hemagglutinin in the influenza virus? ( Concept 19. 3) Your Answer:| Hemagglutinin is involved in assembling the membrane envelope that the virus uses as a cloak when it leaves an infected cell. | | Correct Answer:| Hemagglutinin is the protein that helps the influenza virus attach to host cells. | |   No. Hemagglutinin helps the virus attach to host cells. 26. Birds act as a natural _____ for the influenza _____ virus. Concept 19. 3) Your Answer:| reservoir … C | | Correct Answer:| reservoir … A | | No. Influenza type C only infects humans. 27. Which of the following is an example of vertical transmission of a virus in plants? ( Concept 19. 3) Your Answer:| An infected plant produces seeds that contain the virus, giving rise to infected progeny. |   Correct. Vertical transmission refers to the spread of a virus from parent to offspring. 28. Plant viruses spread throughout the plant by way of _____. ( Concept 19. 3) Your Answer:| the lymphatic system | | Correct Answer:| plasmodesmata | |

No. Plants do not have a lymphatic system. 29. Circular RNA molecules that function like a virus in plants are termed _____. ( Concept 19. 3) Your Answer:| viroid | Correct. Viroids are tiny molecules of circular RNA that infect plants. 30. Prions are _____ that are thought to cause disease by _____. ( Concept 19. 3) Your Answer:| mutant DNA molecules … encoding toxic proteins | | Correct Answer:| abnormally shaped proteins … inducing similar but normally shaped proteins in the brain to adopt the abnormal form | |   No. Prions are proteins. 31.

A new pathogenic form of influenza A can emerge when _____. ( Concept 19. 3) Your Answer:| a virus with a novel genetic makeup recombines with viruses that circulate widely among humans | | Correct Answer:| All of the listed factors likely contribute to the emergence of a new pathogenic strain of influenza A. | |   No. This can contribute to the emergence of a new pathogenic strain of influenza A virus but there is a better answer. 32. What is the prevailing hypothesis for the surprisingly low infection and mortality rate among people over 64 years of age during the 2009 H1N1 pandemic? Concept 19. 3) Your Answer:| Older people were likely exposed to earlier H1N1 viruses that primed their immune systems for the virus of the 2009 pandemic. |   Correct. It is proposed that prior exposure to earlier H1N1 viruses primed the immune system of older people so that they were able to mount an immune response to the recent H1N1 virus. 33. The avian flu virus H5N1 is considered a greater long-term threat than the swine flu virus H1N1 because _____. ( Concept 19. 3) Correct Answer:| it has a significantly higher mortality rate| |

Free Essays

Ap Biology Lab 1 Questions

AP Biology Lab 1 Ross Lordo Introduction Questions 1. The solute potential would be -2. 48. If the concentration inside the cell is . 15 M, then would diffusion out of the cell and into the solution of . 1 M. This is due to water potential and the tendency for water to move from areas of high water potential to low water potential. 2. The turgor pressure must be equal to the water potential if there is no net diffusion.

The cell and environment have reached equilibrium and the movement of water is equal on both sides. Getting Started 1. Kinetic energy is the energy an object possesses due to its motion. The difference between kinetic energy and potential energy is the kinetic energy is the energy of an object that is already in motion and potential energy is the energy possessed by an object at rest. Potential energy is stored energy, while kinetic energy is energy being exerted. 2.

Temperature can affect the rate of diffusion. If the temperature is colder, the rate of diffusion is much slower as a result of all particles becoming closer together. If the temperature is warmer, there is much more energy present and therefore allows for the diffusion to take place at a fast rate. The distance a molecule needs to travel across the membrane can also affect the rate of diffusion. If the distance across the membrane is large, then the rate of diffusion will be much slower and vise versa. 3.

A high temperature can speed up the diffusion process by providing more energy for the molecules and also for eliminating in double bonds in the phospholipid membrane. A low temperature will decline the rate of diffusion, as the particles will have less energy. The distance travelled will also affect diffusion rates. The longer the distance, the slower the diffusion is going to take place. The shorter the distance, the quicker the rate of diffusion 4. Gradients offer a pathway for molecules to go in and out of the cell.

Many molecules are to big to fit through the semipermeable phospholipid membrane and these gradients allow these large molecules to be able to cross through the cell. 5. Most cells are small because diffusion can take place at a quicker rate. The convolutions allow for more space to be able to be used in order to get molecules across the membrane. These small cells allow for materials to quickly be able to reach the cell membrane and get in or out of the cell, without having to make a long journey from an inside part of the cell. . Water will move out of the cell. The high water potential means there is little solute in the cell and more in the outside environment. In order to balance these concentrations, water moves out of the cell and creates equilibrium with the environment. 7. If saltwater is applied to a plant, the plant would shrivel up and die. This is a result of the water moving out of the cells in order to try to balance the concentration of solute compared to inside the cell.

The water movement out of the cell would cause the cell to shrink and the lack of water would eventually cause the plant to die. 8. A plant can control its turgor pressure through its central vacuole and cell wall. If a great amount of water is inside the cell, the central vacuole will take in some of the water to take some of the pressure of the cell wall. The cell wall can also eliminate water from making its way into the cell. The would cause the cell to keep expanding, but slowly eliminate its excess water.

Free Essays

Microbiology Research Paper

Melissa Babajko Microbiology 214BA Dr. May June 6, 2012 Staphylococcus aureus- Is a facultative anaerobic, Gram-positive, salt positive, cocci shaped bacterium. Staphylococcus aureus is found as normal part of the skin floral in the nasal passages and on the skin. An estimated twenty percent of people naturally have harmless Staphylococcus aureus on their skin and are long-term carries for Staphylococcus aureus. Staphylococcus aureus is the most common strand of Staphylococcus in humans to date, spread through skin to skin contact or even skin to object contact that an a person infected with Staphylococcus aureus has touched.

Staphylococcus aureus is coagulase positive, which induces clumping of the cells and of the blood. Staphylococcus aureus has many immune-evasive strategies that make it the most common strand, such as; it produces leukocidin a toxin that kills white blood cells. It also resists opsonization, survives in phagolysosomes, and is lysozyme resistant. Methicillin-resistant S. aureus, abbreviated MRSA, is one of a number of greatly feared strains of S. aureus, which have become resistant to most antibiotics.

MRSA strains are most often found associated with institutions such as hospitals, but are becoming increasingly prevalent in community-acquired infections. Research Study: IBM, the computer company, working on nanoparticles that polymerize into structures that are able to attack MRSA bacteria without harming the healthy tissue around it. Once these polymers come into contact with water in or on the body, they self assemble into a new polymer structure that is designed to target bacteria membranes based on electrostatic interaction and break through their cell membranes and walls.

The physical nature of this action prevents bacteria from developing resistance to these nanoparticles or other antibiotics. The electric charge naturally found in cells is important because the new polymer structures are attracted only to the infected areas while preserving the healthy red blood cells the body needs to transport oxygen throughout the body and combat bacteria. Unlike most antimicrobial materials, these are biodegradable, which enhances their potential application because they are naturally eliminated from the body (rather than remaining behind and accumulating in organs).

They are calling this “nanomedicine” and if the trial tests work this could destroy this superbug and eliminate MRSA from hotspots like hospitals. (http://www. forbes. com/sites/amywestervelt/2012/05/16/how-ibm-plans-to-solve-the-mrsa-problem/) Streptococcus pyogenes- Is a gram- positive, spherical, group a, beta-hemolytic bacterium. Streptococcus pyogenes displays Streptococcus antigen A in its cell wall surface. Streptococcus pyogenes has M-protein on its surface, which are fibrils that are antiphagocytic and are involved in the adherence to the skin and mucos membranes.

Streptococcus pyogenes is a catalase negative bacterium that has a capsule that prevents the bacterium from phagocytosis and neutrophils. Another immune-evasive property of Streptococcus pyogenes is the M-proteins on its surface inhibit opsonization. Streptococcus pyogenes is the cause of many human diseases ranging in severity. Disease in a result to infection includes, pharyngitis (sore throat), impetigo and invasive infections such as, cellulitis and erysipelas.

Research Study: Portuguese scientists are looking at new ways to combat the spread of Streptococcus pyogenes by looking into natural antimicrobials. This work aimed to screen the antimicrobial activity of aqueous methanolic extracts of 13 mushroom species. Scientist used a microdilution method to determine the Minimum Inhibitory Concentration (MIC) and the Minimum Bactericidal Concentration (MBC). MIC results showed that Russula delica and Fistulina hepatica extracts inhibited the growth of Streptococcus pyogenes.

A MBC of 10 mg/ml of Ramaria botrytis extract shoed to have bactericide effects on Streptococcus pyogenes, leading scientist to conclude that mushroom extracts could be a hopeful species as an antimicrobial agent to Streptococcus pyogenes that may be resistant to traditional treatments. (http://www. ncbi. nlm. nih. gov/pubmed/22621239) PMID: 22621239 [PubMed – as supplied by publisher] May 2012 Streptococcus pneumoniae- Is a Gram-positive bacterium in the shape of a slightly pointed cocci. They are usually found in pairs as diplococci.

Streptococcus pneumoniae are alpha hemolytic bacterium. Streptococcus pneumoniae have a polysaccharide capsule that acts as a virulence factor for the organism; along with surface proteins that prevent the activation of complement pathways, and pili that enable S. pneumoniae to attach to epithelial cells in the upper respiratory tract. Streptococcus pneumoniae lacks catalase and ferments glucose to lactic acid, like most other streptococci. However, unlike most other streptococci, it does not display an M protein and it hydrolyzes insulin, which help distinguish it from other streptococci.

Streptococcus pneumoniae is the most common cause of meningitis in adults and young adults throughout the world and is best known for causing pneumonia all other the world. Research Study: Due to a continuing increase in S. pneumoniae’s antibiotic resistance, the search for a better vaccine is ongoing. Research on the Lactococcus lactis bacteria for use as a vaccine is promising; its production of the pneumococcal surface protein PspA makes it a good candidate for a mucosal vaccine, which could be administered through the nose instead of an injection (a promising aspect).

Studies show that the lactococcal vaccine offers better protection against respiratory infection by S. pneumoniae than injections of similar amounts of recombinant PspA administered by injection. There is considerable potential to develop a vaccine with L. lactis, for use against S. streptococcus and more. (http://www. journals. uchicago. edu/JID/journal/issues/v195n2/36706/brief/36706. abstract. html? erFrom=-2043069302250900887Guest) Neisseria gonorrhoeae- Is a gram-negative cocci that are shaped like coffee beans and grow as diplococcic.

Neisseria gonorrhoeae grow on chocolate agar with carbon dioxide and need nutrients to grow in a laboratory setting. Neisseria gonorrhoeae are motile bacterium, which move around by twitching and have type IV pilli to adhere to surfaces. Neisseria gonorrhoeae is able to prevent an immune response by using its surface opa proteins, which bind to receptors on immune cells. This results in the host being unable to develop an immunological memory against Neisseria gonorrhoeae and allow for the possibility of reinfection.

Neisseria gonorrhoeae infections are acquired by sexual contact and usually affect the mucous membranes of the urethra in males and the endocervix and urethra in females. The pathogenic mechanism involves the attachment of the bacterium to nonciliated epithelial cells through pili and the production of lipopolysaccharide endotoxin. Neisseria gonorrhoeae is only found after sexual contact with an infected person (or in the case of infections in the newborn, direct contact).

Research Study- A single dose of cefodizime (CDZM), ceftriaxone(CTRX), or spectinomycin (SPCM) is what is recommended for the treatment of gonococcal urethritis or uterine cervicitis. It was previously found that a single dose of CDZM completely eradicated multidrug-resistant N. gonorrhoeae in patients with urethritis and uterine cervicitis, and so a single 1. 0-g dose of CDZM for the treatment of N. gonorrhoeae pharyngeal infection, including infections with CZRNG was tried. The eradication rate of N. gonorrhoeae from the pharynx was 63. % with a single 1. 0-g dose of CDZM, while the rate for CZRNG with the same dose of CDZM was 38. 5%. N. gonorrhoeae was completely eradicated from the pharynx when patients received one or two additional doses of CDZM. It was found that N. gonorrhoeae was completely eradicated from the pharynx when patients received one or two additional doses of CDZM. Therefore, it can be concluded that two to three doses of CDZM are necessary for the treatment of CZRNG pharyngeal infection. (http://www. ncbi. nlm. nih. gov/pmc/articles/PMC1636252/)

Escherichia coli- Is an aerobic, gram-negative, rod shaped bacteria that can be commonly found in animal feces and in the lower intestines of mammals. Escherichia coli possesses adhesive fimbriae and a cell wall that consists of an outer membrane containing lipopolysaccharides, a periplasmic space with a peptidoglycan layer, and an inner, cytoplasmic membrane. The lipopolysaccharide layer of Escherichia coli contains an endotoxin called lipid A and also have a capsule that help fight against phagocytosis and add to its virulence. Some strains are piliated and capable of accepting and transferring plasmid to and from other bacteria.

Escherichia coli prefer to live at a higher temperature rather than the cooler temperatures. The harmless strains of Escherichia coli are part of the normal flora in the gut and benefit the host organism by producing vitamin K and preventing the development of pathogenic bacteria within the intestine. Although Escherichia coli is harmless in the gut of an organism when it enters the blood stream and travels through the body it then becomes the leading cause for food poisoning among humans and when it enters the urethra it can cause urinary tract infections in both males and females.

Research Study- A study is focusing on exploring the antigens on the outer membrane of the uropathogenic E. coli (UPEC) which can cause uncomplicated urinary tract infection (UTI), and furthermore to design a UTI vaccine to promote protective immunity against UPEC infection. In this sutdy, they apply an immunoproteomics approach to vaccine development that has been used successfully to identify vaccine targets in other pathogenic bacteria. The outer membrane proteins of UPEC from infected mice are separated by two-dimensional gel electrophoresis and are identified by mass spectrometry.

A total of 23 antigens have known roles in UPEC pathogenesis, such as ChuA, IroN, IreA, Iha, IutA, and FliC. After identifying the antigens on outer membrane of UPEC, they demonstrate an antibody targeting directly on these antigens during UTI. This study shows that these conserved outer membrane antigens can be used as rational candidates for a UTI vaccine. (http://www. ncbi. nlm. nih. gov/sites/entrez? Db=pubmed;Cmd=ShowDetailView;TermToSearch=17525800;ordinalpos=7;itool=EntrezSystem2. PEntrez. Pubmed. Pubmed_ResultsPanel. Pubmed_RVDocSum)

Haemophilus influenzae- Is a gram-negative bacterium, which infects the blood stream of the organism, which is shaped like rods and is generally anaerobic in nature but can live as facultative anaerobic. Haemophilus influenzae was discovered around the flu pandemic and was first thought to be the cause of influenza but was disproven shown to be the cause of many other clinical diseases. Haemophilus influenzae has new strands of bacterium that can affect organism there is an unencapsulated strain and an encapsulated strain, which is the most common strain to infect humans.

Haemophilus influenzae lack motility due to their lack of flagella and pilli, the capsulated strains have a polysaccharide capsule which has the endotoxin Lipid A that contributes to Haemophilus influenzae ability to survive in the blood stream. H. influenzae is an opportunistic pathogen that normally lives with in the host without causing any problems but will act on an opportunity such as a compromised immune system to infect the host. The most noted strain; H. influenzae type b causes meningitis, which is an inflection in the membrane around the brain and epiglottitis, which is infection around the throat and trachea.

In general H. Influenzae bacteria lives in the upper respiratory tract, which can be transmitted by close contact with patients. This bacterial infection can also be air born transmitted through sneezing. Research Study- Arnold Smith, M. D. from Seattle Biomedical Research institute, has preformed a research study on how h. influenzae operates. In this research, Dr. Smith’s purpose is to understand how this bacterium causes disease, which can help improved current treatments and preventions. In the lab molecular mechanisms of h. nfluenzae was understood. It was also noted that specific strains of this bacteria have ability to cross the respiratory tract of young children. It was also found that once this infection enters the blood stream it might cause sepsis and meningitis. This research is currently in progress at the Seattle Biomedical Research Institute. (http://www. sbri. org/research/a_smith. asp) Clostridium tetani- is a bacillus, or rod-shaped, bacterium. It is Gram positive and commonly appears to be shaped like a drumstick or tennis racket when stained.

This appearance is due to the sporulation that occurs inside the cell. Clostridium tetani is an obligate anaerobe and relies on fermentation to survive. Clostridium tetani possess a thick cell wall made up of multiple layers of peptidoglycan and one inner membrane. C. tetani are motile bacteria and move with the use of their of rotary flagellum. C. tetani in the presence of oxygen changes into its endospore form, the spores of Clostridium tetani are resistant to resistant to heat and some antiseptics which contribute to its ability to spread and infect organisms.

Clostridium tetani affects humans by causing the disease tetanus. Clostridium tetani enters the body through an open wound where its spores can use the environment created by the dead cells to start its anaerobic processes. The spores begin to produce the toxin tetanospasmin, which travels throughout the body via the nervous system. Once tetanospasmin reaches the spinal cord where it begins to interfere with neurotransmitters which blocks messages to the brain this leads to unwanted muscle contractions and spasms, and individuals can experience severe seizures.

Research Study- A 2008 study in Kano, Nigeria sought to determine the susceptibility of Clostridium tetani to various antibiotics. Soil was collected from five different locations and cultured under anaerobic conditions to observe the number of samples, which contained Clostridium tetani spores. The bacterium was observed in 60% of the soil samples. The samples were treated with amoxicillin, chloramphenicol, tetracycline, erythromycin, augmentin, co–trimoxazole, metronidazol, penicillin V, gentamycin, cloxacillin, sparfloxacin and ciprofloxacin to determine antibiotic susceptibility.

The most effective antibiotic in preventing colony growth was observed to be sparfloxacin, with erythromycin, tetracycline, gentamycin, chloramphenicol, metronidazole and ciprofloxacin also preventing growth. The remaining antibiotics appeared to be inaffective against Clostridium tetani. (http://www. ajol. info/index. php/bajopas/article/viewFile/57539/45918) Mycobacterium tuberculosis- Is a acid fast bacterium that is rod shaped that usually form in clumps and are obligate aerobe. Mycobacterium tuberculosis has a cell envelope that contains a polypeptide layer, a peptidoglycan layer, and free lipids.

In addition, there is also a complex structure of fatty acids such as mycolic acids that appear glossy. These lipids are resoponsible for the mycobacterium survival under environmental stressors. Mycobacterium tuberculosis utilizes its cell envelope to prevent it from drying out and allows it to survive weeks in dried septum also it makes Mycobacterium tuberculosis resistant to chemical antimicrobials. Mycobacterium tuberculosis reaches the lungs of a human by inhalation of bacillus, in the lungs, M. tuberculosis is taken up by alveolar macrophages, but they are unable to digest the bacterium.

Its cell wall prevents the fusion of the phagosome with a lysosome allowing the bacterium to replicate with in the macrophage letting the disease spread. Mycobacterium tuberculosis causes the respiratory disease tuberculosis, which leaves a person infectious to spread the disease through the air, person to person, by the cough that they have devolped from the disease. Tuberculosis can infect anyone but is more common in immunosuppressed patients and if left untreated can be deadly. Vaccinating individuals with the BCG vaccine to stop the spread of this growing global epidemic is doing prevention of the spread of tuberculosis.

Research Study- A group of scientists found that a newly identified protein with carboxyesterase activity is required for the virulence of Mycobacterium tuberculosis. They found that the gene MT2282 encodes a protein that is associated with carboxyesterase. It hydrolyzes ester bonds of the substrate. When a strain containing a mutant of this gene was used to infect mice, the mice’s life was prolonged as compared with those that were infected with the wild type strain. (“Characterization of a novel cell wall-anchored protein with carboyesterase activity required for virulence in Mycobacterium tuberculosis. The Journal of Biological Chemistry 2007) Treponema pallidum- is a Gram-negative bacterium, which is spiral in shape. It is an obligate internal parasite, which causes syphilis, a chronic human disease. Syphilis is a sexually transmitted disease but transmission can also occur between mother and child in utero; this is called congenital syphilis. Syphilis was first discovered in Europe near the end of the fifteenth century. Treponema pallidum is an obligate internal parasite, meaning that it requires a mammalian host for survival. In the absence of mammalian cells, T. allidum will be killed by the absence of nutrients, exposure to oxygen and heat. T. pallidum lacks enzymes necessary to build complex molecules and loses its infectiousness when outside the host mammal for too long. T. pallidum has slim to none virulence factors but it produces several lipoproteins that induce and inflammatory response from the immune system resulting in the tissue destruction that goes along with this disease. Once T. pallidum infects the host it immediately enters the bloodstream and moves through deeper tissue with ease because of their corkscrew-like motility.

Untreated syphilis progresses in a series of distinct stages. Primary syphilis usually presents itself as a single chancre at the site of infection. Secondary syphilis occurs approximately 3 months after infection and presents itself as lesions of the skin and mucous membranes. These include a rash commonly on the palms of the hands, soles of the feet, face, and scalp. The breakdown of mucous membranes appears as patches on lips, inside the mouth, vulva, and vagina. If untreated it may progress to tertiary phase. Tertiary syphilis can cause destructive lesions on skin and bones, which are usually benign.

The more deadly manifestations of late syphilis affect the cardiovascular system and the central nervous system causing infected individuals to experience insomnia and changes in personality. If detected early syphilis is easily eradicated from the host by benzathine penicillin. Research Study- The current method for detecting syphilis is based on recognition of its signs and symptoms followed by blood tests which lack sensitivity and require fresh serum. The goal of this study was to develop a sensitive assay to directly test for syphilis.

They were able to develop a TaqMan real-time PCR assay that was able to detect T. pallidum from “swabs and biopsy specimens from genital and mucosal ulcers, placental specimens, and cerebrospinal fluid. “ Further research is required to confirm the accuracy of this new assay. This will be done by comparing results of this new method against other currently used test for syphilis. (:http://www. pubmedcentral. nih. gov/articlerender. fcgi? tool=pubmed;pubmedid=17065262) Chlamydia trachomatis- Is an obligate, aerobic, intracellular parasite of eukaryotic cells.

It is a Gram-negative bacterium and has a coccoid or rod shape. It has a cytoplasmic membrane and outer membrane similar to Gram-negative bacteria but lacks a peptidoglycan cell wall. C. trachomatis require growing cells in order to remain viable since it cannot synthesize its own ATP. Without a host organism, Chlamydia trachomatis cannot survive on its own. C. trachomatis is the leading cause of sexually transmitted disease worldwide–in the United States, alone, over 4 million cases are diagnosed each year. It is also the leading cause of preventable blindness in the world.

Chlamydia trachomatis is also one of the major causes of pelvic inflammatory disease (PID) and infertility in women. Chlamydia is transmitted through infected secretions only. Usually, Chlamydia trachomatis is asymptomatic in its hosts, but can cause discharge from the penis, pain and burning during urination, infection or inflammation in the ducts of testicles, and tenderness or pain in the testicles. It infects mainly mucosal membranes, such as the cervix, rectum, urethra, throat, and conjunctiva. It is primarily spread via sexual contact and manifests as the sexually transmitted disease.

The bacterium is not easily spread among women, so the STD is mainly transmitted by heterosexual or male homosexual contact. However, infected secretions from the genitals to the hands and eventually to the eyes can cause trachoma. There is no vaccine to stop the spread of Chlamydia but the disease can be cured very eaily with antibiotics. Research Study- Current research uses a live-attenuated form of the influenza A virus to provide viral vector for a vaccine against C. trachomatis. This vaccine is tested to be used intra-nasally. In the experiment, mice were intra-nasally immunized with influenza A viral recombinants.

The result was a very strong immune, T helper 1, response against intact Chlamydia trachomatis elementary bodies. The genital secretions in the mice showed high levels of specific Th1 cells and elevated immunoglobulin G2a, which indicates a possibility of long term, protective immunity. This study, using C. trachomatis, is very important because it indicates that live attenuated vaccines of the influenza virus could be a new and reliable approach to preventing the spread of sexually transmitted disease. (http://www. ncbi. nlm. nih. gov/sites/entrez?

Db=pubmed;Cmd=ShowDetailView;TermToSearch=17451464) Herpes simplex virus I and II- are two members of the herpes virus family, Herpesviridae, that infect humans. The structure of herpes viruses consists of a relatively large double-stranded, linear DNA genome encased within an icosahedral protein cage called the capsid, which is wrapped in a lipid bilayer called the envelope. The envelope is joined to the capsid by means of a tegument. This complete particle is known as the virion. A herpesvirus infection begins with attachment to and penetration of a host cell.

Since herpesviruses are large DNA viruses, and they usually infect non-dividing cells, they encode enzymes involved in nucleic acid metabolism and DNA synthesis so they can copy their DNA once they enter the host cell. Herpesviruses replicate in the nucleus of the host cell. HSV-1 is the cause of oral herpes producing what are commonly known as cold sores. HSV-2 is the cause of genital herpes crating lesions and blisters on the genitals of the infected organism. Ss neurotropic and neuroinvasive viruses, HSV-1 and -2 persist in the body by becoming latent and hiding from the immune system in the cell bodies of neurons.

After the initial or primary infection, some infected people experience sporadic episodes of viral reactivation or outbreaks. In an outbreak, the virus in a nerve cell becomes active and is transported via the neuron’s axon to the skin, where virus replication and shedding occur and cause new sores. HSV-1 and -2 can both be treated but never cured and rid from the body. Research Study- In this study, researchers applied an experimental feedback system control (FSC) method and rapidly identified optimal drug combinations that inhibit herpes simplex virus-1 infection, by only testing less than 0. % of the total possible drug combinations. Using antiviral efficacy as the criterion, FSC quickly identified a highly efficacious drug cocktail. This cocktail contained high dose ribavirin. Ribavirin, while being an effective antiviral drug, often induces toxic side effects that are not desirable in a therapeutic drug combination. To screen for less toxic drug combinations, we applied a second FSC search in cascade and used both high antiviral efficacy and low toxicity as criteria. Surprisingly, the new drug combination eliminated the need for ribavirin, but still blocked viral infection in nearly 100% of cases.

This cascade search provides a versatile platform for rapid discovery of new drug combinations that satisfy multiple criteria. (http://www. ncbi. nlm. nih. gov/pubmed/22654513) Epstein-Barr virus- Epstein Barr Virus (human herpesvirus 4 or EBV) is a member of the herpesvirdidae family. Epstein Barr Virus is the most common and most successful human virus. Epstein Barr Virus occurs worldwide, affecting anyone at any point in his or her lifetime, selectively infecting B-lymphocytes. Once infected the virus stays with the person for the rest of their life, remains latent in B cells after recovery from the disease.

The structure of Epstein-Barr virus is a icosahedral nucleocapsid. The nucleocapsid is composed of 162 capsomers. The nucleocapsid is then surrounded by a protein outer covering, which is then surrounded by a viral envelope that contains numerous glycoproteins. EBV only infects humans. Replication of Epstein Barr Virus can occur in two ways: Infection of skin cells that results in lysis of host cells and release of virions. ; primary B-cell that results in latency infection. During this stage the virus is constantly being repilicated.

The most common condition that EBV is associated with is infectious mononucleosis, which is transmitted via saliva and is characterized by proliferation of lymphocytes. The symptoms of infectious mononucleosis are fever, fatigue, sore throat, tonsillitis, adenopathy and hetatomegaly. The virus causes disease either by lysis of host cells to release virions or by continuous replication during the latency cycle. Research Study- Vaccine production- scientists are researchers are trying to create a vaccine for prevention of Epstein Barr Virus.

The problem is with all the diseases that are caused by EBV, would be difficult to cure these diseases. Also most people with EBV don’t even know they have it and if there aren’t any clincial symptoms reported, researchers cannot create a vaccine. (2007. Pathogenesis and Therapy of Epstein-Barr Virus Infection: Novel Therapeutic Approaches. 1-37. In: New Developments in Epstein-Barr Virus Research. ) Hepatitis C virus- The virions of Hepatitis C virus are spherical and consist of an envelope and a nucleocapsid, a detergent sensitive lipoprotein envelops the virus capsid.

The genome of hepatitis C virus is not segmented and contains a single molecule of linear positive-sense, single stranded RNA. Hepatitis C virus is spread by blood-to-blood contact, through unsterilized medical equipment, healthcare exposure, sexual intercourse, and drug use, its as only existent in humans and chimpanzees. The disease primarily affects the liver but often shows no sign of infection. When this viral disease reaches the chronic stage it leads to inflammation of the liver leading to the formation of scar tissue and cirrhosis. Cirrhosis can lead to liver failure or cancer and may result in the infected needing a liver transport.

There is no vaccine currently available for the Hepatitis C virus. Research Study- Researchers conducting a open-label, phase 2a study included an exploratory cohort of 21 patients with chronic HCV genotype 1 infection who had not had a response to previous therapy. Researchers randomly assigned patients to receive the NS5A replication complex inhibitor daclatasvir (60 mg once daily) and the NS3 protease inhibitor asunaprevir (600 mg twice daily) alone (group A, 11 patients) or in combination with peginterferon alfa-2a and ribavirin (group B, 10 patients) for 24 weeks.

The primary end point was the percentage of patients with a sustained virologic response 12 weeks after the end of the treatment period. This preliminary study involving patients with HCV genotype 1 infection who had not had a response to prior therapy showed that a sustained virologic response can be achieved with two direct-acting antiviral agents only. In addition, a high rate of sustained virologic response was achieved when the two direct-acting antiviral agents were combined with peginterferon alfa-2a and ribavirin. (http://www. ncbi. nlm. nih. ov/pubmed/22256805) Hepatitis B virus- The virion consists of an outer lipid envelope and an icosahedral nucleocapsid core composed of protein. These virions are sometimes referred to as “Dane particles”. The nucleocapsid encloses the viral DNA and a DNA polymerase that has reverse transcriptase activity. The outer envelope contains embedded proteins that are involved in viral binding of, and entry into, susceptible cells. Hepatitis B virus is one of the smallest enveloped animal viruses. The protein of the virion coat is known as “surface antigen” or HBsAg.

Hepatitis B virus is only found in humans and chimpanzees and was originally known as the serum virus. The virus is transmitted by exposure to infectious blood or body fluids such as semen and vaginal fluids. The acute illness causes liver inflammation, vomiting, jaundice and, rarely, death. Chronic hepatitis B may eventually cause cirrhosis and liver cancer but this disease responds poorly to treatment. Hepatitis B virus is currently preventable by vaccination. Research study- One thousand twenty pregnant women and 946 patients visiting for routine checkups were screened for HBV and HDV infection.

Demographic, epidemiological, ethnic, clinical, and biological data were recorded. In pregnant women, exposure to HBV was significantly associated in multivariate analysis with education level, ethnicity, blood transfusion, and occupation. HDV antibodies (HDVAb) were found in 14. 7% of pregnant women. In patients, HBsAg was found less frequently in females than in males. Again in multivariate analysis, exposure to HBV was significantly correlated with gender (males), and HDVAb positivity with age and gender.

This study confirms the high prevalence of HBV and HDV infections in Mauritania and demonstrates the high genetic diversity of HBV in this country. (http://www. ncbi. nlm. nih. gov/pubmed/22711346) Influenza A virus- Is more commonly known as bird flu or avian influenza. Influenza A virus is part of the Orthomyxoviridae group. Influenza A viruses are negative sense, single-stranded, segmented RNA viruses. There are two different classifications of Influenza A virus, highly pathogenic avian influenza (HPIA) and mildly or non-pathogenic avian influenza (MPIA).

The virus has a protein envelope encasing it. There are different variations of Influenza A virus based on their H number (for the type of hemagglutinin) and an N number (for the type of neuraminidase), which gives it the name H1N5. Wild birds are the natural host for all known subtypes of Influenza A viruses but it is known to infect domestic birds as well becoming a natural killer for them and also passing this disease, although rare, onto humans. There is currently a Influenza A virus vaccine developed to help stop the spread of an Influenza A virus epidemic if one were to ever occur.

Research Study- Researches debate on a global scale, about bioethics, biohazard, bio weaponry and bioterrorism issues related to scientific research concerning the induced transition of the highly lethal H5N1 avian flu virus from a non-pandemic to a tentatively pandemic strain, which might fall into malevolent hands. Appreciable ecogenetic complexity marks the main attributes of influenza type A viruses, namely infectivity, virulence, antigenicity, transmissibility, host range, endemicity, and epidemicity. They all shape, conjunctively, the outstanding protean nature of this pathogen, hence the modularity of the latter as a potent weapon.

Altogether, a variety of interrelated properties underlying the complicatedness of and menaces posed by influenza A virus as a grave medical challenge, a dually explorable pathogen, and a modular biological warfare agent, are thereby illuminated, alongside with their scientific, strategic and practical implications. (http://www. ncbi. nlm. nih. gov/pubmed/22690739) Human immunodeficiency virus- Is a positive-sense single stranded RNA virus that belongs to the genus Lentivirus and the family Reteroviridae. The virions of an HIV consist of an envelope, a nucleocapsid, a nucleoid, and a matrix protein. The virus capsid is enveloped.

The virions are spherical to pleomorphic with small but high numbers of surface projections that are called glycoprotein spikes that allow the virus to dock to amplifier cells slowing down immune system response. The replication of HIV can only take place inside human cells. The process typically begins when a virus particle bumps into a cell that carries a special protein called CD4 on its surface. The spikes on the surface of the virusparticle stick to the CD4 to allow the viral envelope to fuse with the cell membrane. HIV particle contents are then released into the cell, leaving the envelope behind.

The HIV enzyme reverse transcriptase converts the viral RNA into DNA, which is compatible to human genetic material, when the virus is inside the cell. This DNA is transported to the cell’s nucleus, where it is spliced into human DNA by the HIV enzyme integrase. The HIV DNA is known as provirus after it is integrated. HIV takes over the body by attacking CD4 helper T cells lowering its levels leaving the body unable to create a proper immune response and leaving it susceptible to infection. Human immunodeficiency virus has three stages in its infectious process before full-blown Acquired Immunodeficiency Syndrome is in motion.

Human immunodeficiency virus has a short life surviving just 6 hours outside the cell and 1 and ? days inside the cell. Sexual contact, breast milk, transplants, and blood-to-blood contact transmit human immunodeficiency virus. Human immunodeficiency virus is the causative agent of Acquired Immunodeficiency Syndrome (AIDS), which leads to many other opportunistic infections, leading most people to die from the new infections rather then AIDS or HIV itself. There is currently no vaccine or treatment for Human immunodeficiency virus but with proper precautionary measures you can control the spread of the virus.

Research Study- Researches have discovered that SAMHD1 restricts the infection of dendritic and other myeloid cells by human immunodeficiency virus type 1 (HIV-1), but in lentiviruses of the simian immunodeficiency virus of sooty mangabey (SIVsm)-HIV-2 lineage, SAMHD1 is counteracted by the virion-packaged accessory protein Vpx. Here we found that SAMHD1 restricted infection by hydrolyzing intracellular deoxynucleoside triphosphates (dNTPs), lowering their concentrations to below those required for the synthesis of the viral DNA by reverse transcriptase (RT).

SAMHD1-mediated restriction was alleviated by the addition of exogenous deoxynucleosides. An HIV-1 with a mutant RT with low affinity for dNTPs was particularly sensitive to SAMHD1-mediated restriction. Vpx prevented the SAMHD1-mediated decrease in dNTP concentration and induced the degradation of human and rhesus macaque SAMHD1 but had no effect on mouse SAMHD1. Nucleotide-pool depletion could be a general mechanism for protecting cells from infectious agents that replicate through a DNA intermediate. (http://www. ncbi. nlm. nih. gov/pubmed/22327569) Trichomonas vaginalis- Is a parasitic, flagellated protozoan anaerobe.

The appearance of this protozoan is altered by physiochemical conditions. In a pure culture, the shape is more uniform such as pear-shaped or oval. As a parasite, it appears more amoeboid when attached to the vaginal epithelial cells. It has five flagella—four of which are in the anterior and the other flagellum is incorporated within the undulating membrane. The flagella and the undulating membrane contribute to its motility. The cytoskeleton is made of tubulin and actin fibers. The nucleus, surrounded by a porous nuclear envelope, is located at its anterior end.

A thin hyaline, rod-like structure called the axostyle begins at the nucleus and bisects the protozoan longitudinally. It protrudes through the posterior portion of the protozoan, ending in a sharp point. The axostyle helps anchor the protozoan to the vaginal epithelial cells. Trichomonas vaginalis causes Trichomoniasis which is the most prevalent non-viral sexually transmitted disease. Trichomoniasis is more common in women than men because men have asymptomatic infections. For women, the symptoms are thin frothy, green-yellow vaginal discharge; vulvovaginal irritation, vaginal soreness, and redness of the vagina.

Women also have a higher prevalence of invasive cervical cancer when they have trichomoniasis. During pregnancy, there is an increased risk of preterm and low weight babies. Men have non-gonoccocal urethritis and chronic prostatitis. This infection has been found to be associated with prostate cancer. In both sexes, there is a higher susceptibility to HIV and infertility. There are no vaccines avaliabe for to decrease the spread of Trichomonas vaginalis but Trichomoniasis is a curable disease with antibiotics.

Research Study- Besides being transmitted sexually, there have been cases of nonsexual transmission of trichomoniasis such as contaminated douche nozzles, specula, toilet seats, or swimming pool water. The role of public swimming pools in spreading the disease is controversial yet there is little research done. The viability of T. vaginalis in samples of water was reexamined by Pereira-Neves and Benchimol. They concluded that T. vaginalis remains viable and infective in swimming pool water samples for several hours. The survival time is dependent on the cytotoxicity of the strain.

The possible transmission of trichomoniasis in public swimming pools may be low. (http://www. mendeley. com/research/trichomonas-vaginalis-vitro-survival-swimming-pool-water-samples/) Plasmodium species- Is a parasite that forms sporozites and is the cause for human malaria. There are four types of Plasmodium that cause human malaria: Plasmodium falciparum, Plasmodium ovale, Plasmodium vivax, and Plasmodium malariae. The sporozoites have a thin outer membrane, a double inner membrane below which lies the subpelicular microtubules. They have 3 polar rings and the rhoptries are long, extending half the length of the body.

The micronemes, convoluted elongate bodies, run forward to the anterior of the sporozoite entering a common duct with the rhoptries. After entering the circulatory system, the sporozoites make quick work of invading liver cells using the apical organelles inside the host’s liver cell the Plasmodium cell undergoes asexual replication. The products of this replication, called merozoites, are released into the circulatory system. The merozoites invade erythrocites and become enlarged ring-shaped trophozoites. In this stage the cells ingest the host cytoplasm and proteolyze hemoglobin into amino acids.

Plasmodium species infect humans by an infected Anophele mosquito bites a human and the sporozoites of a Plasmodium species are injected into the blood with the saliva causing malaria. Malaria symptoms may go unnoticed or misdiagnosed; clinical signs include fever, chills, weakness, headache, vomiting, diarrhea, anemia, pulmonary and renal dysfunction, neurologic changes and untreated malaria may result in death. To prevent the spread of malaria precautions are being taken to monitor the dsease with in the mosquito population and measure and taken to reduce it.

Research Study- Incidence rates and vulnerability to malaria are linked to low socioeconomic status. Areas with concentrated populations of people with low socioeconomic status typically do not have resources for effective prevention and subsequent treatment. For example, a study conducted by Gwatkin and Guillot showed “58% of malaria deaths occurred in the poorest 20% of the world’s population, a higher percentage than any other disease of major public health importance”. Public health interventions intended to reach areas with people of low socioeconomic status may not be reaching their target population. Barat et al. ote that in developing countries, the poor “often live in the most remote areas and are socially or culturally marginalized” (http://www. cdc. gov/malaria/) Candida albicans- is a diploid fungus that grows both as yeast and filamentous cells and a causal agent of opportunistic oral and genital infections in humans and id the number one cause of yeats infections in the U. S.. Candida albicans is commensal and a constituent of the normal gut flora comprising microorganisms that live in the human mouth and gastrointestinal tract. C. albicans lives in 80% of the human population without causing harmful effects.

Candidiasis is often observed in immunocompromised individuals such as HIV-infected patients. A common form of candidiasis restricted to the mucosal membranes in mouth or vagina is thrush, which is usually easily cured in people who are not immunocompromised. To infect host tissue, the usual unicellular yeast-like form of C. albicans reacts to environmental cues and switches into an invasive, multicellular filamentous form, a phenomenon called dimorphism. Treatment is easily achieved by various medicines including antifungal drugs and topical ointments.

Research Study- Recent research is still being conducted in hopes of finding a permanent means of dealing with Candida albicans and its resistance to certain drugs. Just within the last year, a Japanese university has taken the steps to specifically target the areas which allow the fungus to have resistance. They have observed that an ATP efflux inactivates the CDR1 and CDR2 genes which are responsible for drug resistance. Without the proper energy to activate the pump to rid of the antifungal agents, the resistance itself is in fact inoperable.

The research team has also tried targeting other areas, such as stopping the production of mannan and glucan to prevent the structure of the cell wall. However, their main results show the cooperation between peptides and antifungal drugs. The results of this research will be used to treat other fungal and possible bacterial microbes that have drug resistant qualities (Antimicrobial peptides enhance the candidacidal activity of antifungal drugs by promoting the efflux of ATP from Candida cells. ” Journal of Antimicrobial Chemotherapy. 2007)

Cryptococcus neoformans- Is a round encapsulated yeast that causes meningitis in humans. The disease is acquired by coming in contact with contaminated soil but especially in solid that is contaminated with bird droppings. Cryptococcus neoformans reproduces by budding and produces spores that are then inhaled by a person. Once the dried fungi spores are inhaled the spread through out the central nervous system causing meningitis and severe lung infections. Cryptococcus neoformans is especially dangerous for immunocompromised individuals such as AIDS patients, and also has a mortality rate of 30%.

Cryptococcus neoformans can be treated with an antifungal medicine called fluconazole. Research Study- Dendritic cells (DCs) play a pivotal role in host defense against invading pathogens including fungi, while DCs are targeted by fungi for deleterious regulation of the host immune response. A few studies have reported fungal modulation of DC function in these immunocompromised AIDS patients. Cryptococcus. neoformans (C. neoformans) is referred as one of the opportunistic fungi of AIDS. Here, researchers isolated native C. neoformans from an AIDS patient and investigated its effects on DC activation and

Free Essays

Human Biology Unit 1 Organelle Structure and Function

[pic] ASSIGNMENT GUIDELINES |Theme and Unit title: Human Biology |Student Name: | |Unit 1 – Cells and Tissues | | |Title of assignment: Assignment 1: Short answer question paper- in class/open book examination. | |Date issued: Week 2 – w/c 13. 09. 10 |Submission date: Week 6 w/c 11. 10. 0 | | | | | | | | | | | | | | | | | | | | | | | |ASSIGNMENT GUIDELINES | | | |This assignment consists of a short answer question paper (SAQP) which will be completed as an open book examination in week 6, i. e. in class in timed | |condition with access to an agreed number of resources. | | |You may bring into this examination the following two sets of PowerPoint handouts as issued in class: PP2 – “Cells ” and PP5 – “Tissues of the Human | |Body” | | | |These Power Point handouts may be annotated with your own notes taken during class and after class following any additional reading. You will also have | |access to these two Power Points on-line via the student shared drive. The time allocated to complete the paper is 2 hours. | | | |In addition to the guidance overleaf, examples to illustrate what is required to meet the grading criteria, will be discussed in class. | | |PLEASE ENSURE THESE GUIDELINES ARE SUBMITTED WITH YOUR ASSIGNMENT | | | | | |LEARNING OUTCOMES | | | |1. 0 Understand the component nature of a generalised cell. | | | |5. 0 Understand that human body cells are specialised for a variety of different functions. | | | |6. Understand the structure and function of the major body tissue types | | | |ASSESSMENT CRITERIA LEVEL 2 | |1. 1 Accurately label a diagram of a generalised human cell showing the: nucleus, cytoplasm, cell membrane and mitochondria. | |1. 2 Describe the function of the organelles in 1. 1 | | | |5. 1 Accurately draw and label at least two different specialised human body cells. | | | |5. 2 Describe the functions of the cells drawn in 5. | | | |6. 1 Describe the structure and function of the major body tissue types. | | | | | |ASSESSMENT CRITERIA LEVEL 3 | |1. 1 Accurately label a diagram of a generalised human cell showing the: nucleus, cytoplasm, cell membrane and mitochondria, endoplasmic reticulum, | |ribosomes, lysosomes, centrioles, and golgi apparatus. | |1. 2 Explain the functions of the organelles in 1. | | | |5. 1 Produce accurately scaled, labelled drawings of at least two different specialised human body cells. | |5. 2 With reference to the examples in 5. 1 explain the importance of complementarity of structure and function. | |6. 1 Explain the structure and function of the major body tissue types. | If all learning outcomes are achieved at level 3 the assignment will be graded according to the grade descriptors below. For this assignment grading criteria 5 and 7 apply. Descriptor |Content for merit |Content for distinction |Guidance | | | | | | |5. Communication and |The assignment work shows a very |The assignment work shows an excellent |Diagrams of the cells drawn in questions 1a and 1b | |presentation |good command of: |command of: |are clear and neatly presented with all parts | | |Use of images |Use of images |labelled as instructed. | | | | | | | | |The appropriate biological terms are included and | | |Language (including technical or |Language (including technical or |used correctly throughout the assignment. | | |specialist language. ) |specialist language. ) | | | | | | | |7. The assignment work is: |The assignment work is: |Make sure that you have clearly organised the | |Quality |Structured in a way that is | |resources that you are allowed to bring into the | | |generally logical and fluent. |Structured in a way that is |examination room. | | | |consistently logical and fluent. | | | |Taken as a whole demonstrates a | |Make sure that you are familiar with these in order| | |very good response to the demands|Taken as a whole demonstrates an |that you can use them effectively to complete the | | |of the brief/assignment. |excellent response to the demands of |assignment in the time given. | | |the brief/assignment | | | | | |When using written prose this should be fluent and | | | | |explanations should be presented clearly and | | | | |logically. | | | | | | | | | |Writing should be in blue or black ink, diagrams | | | | |should be drawn in pencil. | | | | | | | | |There should be evidence that explanations are in | | | | |your own words. | [pic] FEEDBACK SHEET |Theme and Unit title: Human Biology |Student Name: | |Unit 1 – Cells and Tissues | | |Title of assignment: Assignment 1: Short answer question paper- in class/open book examination. | |Date issued: Week 2 – w/c 13. 09. 10 |Submission date: Week 6 w/c 11. 10. 0 | |Markers comments: | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |Initial submission level awarded: |Resubmission level awarded: | | | | |TUTOR/ASSESSOR : Janet Vickers |TUTOR/ASSESSOR : Janet Vickers | |SIGNED: |SIGNED | |DATE: |DATE: | |INTERNAL VERIFIER |INTERNAL VERIFIER | |SIGNED: SIGNED: | |DATE: |DATE | |Learning Outcomes: | |Level achieved 1st submission | |Level achieved 2nd submission | | | | | |1. 0 Understand the component nature of a generalised cell. | | | | | | | | | | |5. 0 Understand that human body cells are specialised for a variety of different functions. | | | | | | | | | |6. Understand the structure and function of the major body tissue types | | | | | | | |Assessment Criteria | |Met (()/Not Met(x) | | | |To achieve at Level 2 you need to: | |1st sub | |2nd sub | | | |1. 1 Accurately label a diagram of a generalised human cell showing the: nucleus, cytoplasm, cell membrane and mitochondria. | | | | | | |1. 2 Describe the function of the organelles in 1. 1 | | | | | | | | | | | |5. 1 Accurately draw and label at least two different specialised human body cells. | | | | | | | | |5. 2 Describe the functions of the cells drawn in 5. 1 | | | | | | | | | | | |6. 1 Describe the structure and function of the major body tissue types. | | | | | | | | | | |Met(()/Not Met(x) | | | |To achieve at Level 3 you need to: | |1st sub | |2nd sub | | | |1. 1 Accurately label a diagram of a generalised human cell showing the: nucleus, cytoplasm, cell membrane and mitochondria, endoplasmic reticulum, | |ribosomes, lysosomes, centrioles, and golgi apparatus. | | | | | | |1. 2 Explain the functions of the organelles in 1. 1 | | | | | | | | | | | |5. 1 Produce accurately scaled, labelled drawings of at least two different specialised human body cells. | | | | | | | | |5. 2 With reference to the examples in 5. 1 explain the importance of complementarity of structure and function. | | | | | | | | | |6. 1 Explain the structure and function of the major body tissue types. | | | | | | | | | | |If all learning outcomes are achieved at level 3 the assignment will be graded for this assignment grading criteria 5 and 7 apply. | |Descriptor |Grade awarded |Comment | |5. | | |Communication and presentation | | | | | | | | | | | | | | | | | | | |7. | | |Quality | | | | | | | | | | | | | | | | | | | | | | | Markers comments: | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | ———————– Access to Higher Education: Health Studies/Combined Studies

Work presented in an assessment must be your own. Plagiarism is where a student copies work from another source, published or unpublished (including the work of another student) and fails to acknowledge the influence of another’s work or to attribute quotes to the author. Plagiarism is an academic offence. If you are thought to have plagiarised someone else’s work this could result in disciplinary action. I have read the above information and I can confirm that this work is my own, and that any sources used have been acknowledged using the appropriate referencing system. Signature:………………………………………………………………….. Date: …………………………………………… Access to Higher Education: Health Studies/Combined Studies

Free Essays

Ib Biology Hl2 – 6.1 (Digestion)

6. 1. 1 Explain why digestion of large food molecules is essential. There are two reasons why the digestion of large food molecules is vital. Firstly, the food we eat is made up of many compounds made by other organisms which are not all suitable for human tissues and therefore these have to be broken down and reassembled so that our bodies can use them. Secondly, the food molecules have to be small enough to be absorbed by the villi in the intestine through diffusion, facilitated diffusion or active transport and so large food molecules need to be broken down into smaller ones for absorption to occur.

Summary: ? 1. Food needs to be broken down and reassembled. 2. Large food molecules need to be broken down into smaller ones. 6. 1. 2 Explain the need for enzymes in digestion. Enzymes are needed in the process of digestion as they are the biological catalysts which break down the large food molecules into smaller ones so that these can eventually be absorbed. Digestion can occur naturally at body temperature, however this process takes a very long time as it happens at such a slow rate. For digestion to increase in these circumstances, body temperature would have to increase as well.

However this is not possible as it would interfere with other body functions. This is why enzymes are vital as they speed up this process by lowering the activation energy required for the reaction to occur and they do so at body temperature. Summary: ? 3. Enzymes break down large food molecules into smaller ones. 4. Speed up the process of digestion by lowering the activation energy for the reaction. 5. Work at body temperature. 6. 1. 3 State the source, substrate, products and optimum pH conditions for one amylase, one protease and one lipase.

AmylaseProteaseLipase EnzymeSalivary AmylasePepsinPancreatic Lipase SourceSalivary GlandsChief cells in stomach liningPancreas SubstrateStarchProteinsTriglycerides such as fats and oils ProductsMaltoseSmall polypeptidesFatty Acids and Glycerol Optimum pHpH 7 pH 1. 5 – 2pH 7 6. 1. 4 Draw and label a diagram of the digestive system. ?Figure 6. 1. 1 – The digestive system 6. 1. 5 Outline the functions of the stomach, small intestine and large intestine. The stomach is an important part of the digestive system.

Firstly it secretes HCL which kills bacteria and other harmful organisms preventing food poisoning and it also provides the optimum conditions for the enzyme pepsin to work in (pH 1. 5 – 2). In addition, the stomach secretes pepsin which starts the digestion of proteins into polypeptides and amino acids. Theses can then be absorbed by the villi in the small intestine. The small intestine is where the final stages of digestion occur. The intestinal wall secretes enzymes and it also receives enzymes from the pancreas.

However the main function of the small intestine is the absorption of the small food particles resulting from digestion. It contains many villi which increase the surface area for absorption. The large intestine moves the material that has not been digested from the small intestine and absorbs water. This produces solid faeces which are then egested through the anus. Summary: Stomach: 6. Secretes HCL which kills bacteria. 7. HCL provides optimum pH for pepsin. 8. Secretes pepsin for protein digestion. Small intestine: 1. Intestinal wall secretes enzymes 2. Receives enzymes from the pancreas. . Has villi for absorption of food particles. Large intestine: 1. Moves material that has not been digested along. 2. Absorbes water. 3. Produces faeces. 6. 1. 6 Distinguish between absorption and assimilation. Absorption occurs when the food enters the body as the food molecules pass through a layer of cells and into the bodies tissues. This occurs in the small intestine which has many villi that are specialised for absorption. Assimilation occurs when the food molecules becomes part of the bodies tissue. Therefore, absorption is followed by assimilation. 6. 1. Explain how the structure of the villus is related to its role in absorption and transport of the products of digestion. The structure of the villus is very specific. Firstly there is a great number of them so this increases the surface area for absorption in the small intestine. In addition the villi also have their own projections which are called microvilli. The many microvilli increase the surface area for absorption further. These microvilli have protein channels and pumps in their membranes to allow the rapid absorption of food by facilitated diffusion and active transport.

Also, the villi contains an epithelial layer which is only one cell layer thick so that food can pass through easily and be absorbed quickly. The blood capillaries in the villus are very closely associated with the epithelium so that the distance for the diffusion of the food molecules is small. This thin layer of cells contains mitochondria to provide the ATP needed for the active transport of certain food molecules. Finally, there is a lacteal branch at the centre of the villus which carries away fats after absorption. ?Figure 6. 1. – Intestinal villus? Summary:? 9. Many villi increase the surface area for absorption. 10. Epithelium is only one cell layer thick and so food is quickly absorbed. 11. Microvilli on the villi increase the surface area for absorption further. 12. Protein channels and pumps are present in the microvilli for rapid absorption. 13. The mitochondria in the epithelium provide ATP needed for active transport. 14. Blood capillaries are very close to the epithelium so diffusion distance is small. 15. The lacteal takes away fats after absorption.

Free Essays

Food Microbiology

CHAPTER I INTRODUCTION 1. 1 Background Food is one of human sources of calorie, protein, fats, and nutrition. Yet, because of the highly nutritious content, food is susceptible to growth of microorganisms. By the presence of microorganisms in food, the food is more likely to have shorter shelf life. Thus, mostly it is resolved by the addition of antimicrobial substances to food, such as condiments and preservatives. Condiments and preservatives could inhibit the growth of microorganisms or even destroyed them, as they have antimicrobial agents.

Some examples of condiments and preservatives are ginger, clove, sodium benzoate, garlic, and coriander. The factors contributing in the effectiveness of condiments and preservatives in inhibiting the growth of microorganisms are the concentration of the antimicrobial, temperature, characteristic of the microorganisms and food, storage time. As different types of microorganisms have different resistance toward the antimicrobial substance, it is important to understand the characteristic of the microorganisms towards the antimicrobial agent.

There are two types of resistance: intrinsic resistance and acquired resistance. There are some methods of observing the capability of the condiments in inhibiting the growth of microorganisms. In the experiment, the method used is well diffusion method, which used different type of condiments and added into holes of agar, where by the inhibition zone by the condiments could be observed. The larger the inhibition zone, the more effective the condiment was in inhibiting the growth of microorganisms. 1. 2 Objectives By conducting the experiment, students are expected to learn and observe he effectiveness of antimicrobial substance consisted in condiments and potassium sorbate towards the growth of microorganisms. CHAPTER II LITERATURE REVIEW 2. 1 Antimicrobials Referring to Volk and Wheeler (1993), antimicrobials are the substances that are used to inhibit or kill pathogenic or non-pathogenic microbes. Antimicrobials are also often used as sanitizers and preservatives. Sanitizer is an agent to decrease the amount of microorganisms to the acceptable level. It is generally used in food processing equipments. Antimicrobials are grouped into natural antimicrobials and chemical antimicrobials.

According to Fardiaz (1992), antimicrobials may be microstatic, which is inhibitory to the growth of microbes, and microcidal, which means able to kill microbes. Fruit extract is one most susceptible food materials and thus, is often added with preservatives, especially chemical preservatives, stored at low temperature, or pasteurized. Pasteurization is a heating process at 63? C for thirty minutes. This process is aimed to preserve the stability of the food materials (Buckle et al. , 1987). The growth of microbes can be controlled by using various methods, namely physical method, chemical method, and immunological method.

The control of microorganism growth is performed to kill the microbes, to inhibit the microbes, and to destroy the microbes. Physical controls can be performed by sterilization with heating or radiation and filtering. Chemical controls can be carried out by using chemical antimicrobial compounds, such as disinfectants and preservatives. Whereas immunological controls can be performed by vaccination (Batzing, 2002). 2. 2 Active Antimicrobial Compounds in Spices 2. 2. 1 Garlic Garlic come from the onion family and are an erect biennial herb, which grow annually. It has irregular roots, condensed, flattened step and narrow and has lat leaves. Garlic’s bulb consists of 6 to 35 bulblets called cloves which enclosed in a thick whitish, glistening, and transparent covering (Anonym1, 2000). According to Ankri and Mirelman (1999), garlic or Allium sativum or lahsoon in Indian name is an edible plant, which has been generating a lot of interest as a medicinal panacea and a cure for a wide variety of different conditions since the human history has begun. It is reported to have anticancer effects and to reduce blood lipids in human body. Figure 2. 1 shows the approximate composition of fresh garlic. Figure 2. The approximate composition of fresh garlic Source: Ahmad (1996) The active compound found in garlic cloves which have an unusual concentration of sulfur-containing compounds (1-3%) is called allicin. It is a volatile molecule, which is poorly miscible in aqueous solution, and has a strong typical odor of crushed garlic. Chemically, allicin can be synthesized by mild oxidation of diallyl disulfide as presented in Figure 2. 1. It is to be noticed in Figure 2. 2 that there is a compound called alliin which is a stable precusor, that later will be converted to allicin by enzyme called alliinase present in cloves too.

Moreover, alliinase is surprisingly found in large amounts in cloves, which is about 10% of the total protein content. Practically, allicin is produced when garlic cloves are cut into or crushed (Ankri and Mirelman, 1999) Figure 2. 2 Generation of allicin in a garlic clove Source: Ankri and Mirelman (1999) According to Ankri and Mirelman (1999), there are several biological activities in allicin such as its activity as an antioxidant and its ability to attack the sulphur (SH) groups in enzymes and proteins while modifying their activities as well.

Furthermore, allicin can rapidly penetrate into cells through the cell membranes. In its pure form, allicin has been reputed to exhibit antibacterial activity against a wide range of Gram-negative and Gram-positive bacteria, for instance Escherichia coli that is known to be a multidrug-resistant enterotoxicogenic strains, Salmonella, Staphylococcus, Streptococcus, Klebsiella, Proteus, Bacillus, and Clostridium. It also has antifungal activity that prevents the formation of mycotoxins such as the aflatoxin of Aspergillus parasiticus.

Allicin has shown the anticandida activity towards and is effective against the group species of Candida, Cryptococcus, Trichophyton, Epidermophyton, and Microsporum at only low concentration since it inhibits both the germination of spores and the formation of hyphae. Referring to Dobre et al. (2011), allicin can also attack Aspergillus, Fusarium, and Penecillium species, which are responsible for food poisoning and food decay.

The main mechanism of the antimicrobial activity in allicin is the inhibition of certain thiol-containing enzymes in the microorganisms by the super fast reaction of thiosulfinates with thiol groups, such as alcohol dehydrogenase, thioredoxin reductase, and RNA polymerase that later will affect the essential metabolism of cysteine proteinase activity. The reason why microbial cells are highly sensitive to allicin is probably because the lack of glutathione (thiol molecules such as trypanothione) which results of lack of the ability to reactivate the pivotal SH-enzymes that are thiolated by allicin (Ankri and Mirelman, 1999). . 2. 2 Coriander Coriander or Coriandrum sativum L. is originated from the Mediterranean region and has the appearance of flat shape in the one side while slightly pointed shape is found in the other side. Coriander seed has various lengths between 3 to 5 mm with brown color in ripe state (Sarkar, 2012). Accodring to Rattanachaikunsopon and Phumkhachorn (2010), it has been traditionally used as an analgesic, aphrodisiac, antirheumatic, anti-inflammatory, diuretic, antispasmodic, circulatory stimulant, and antidiabetic. Beside that, coriander is known to have effect in lowering cholesterol. Table 2. shows the composition of coriander seed. Table 2. 3 The coriander seed composition in 1 tsp Total Fat 0. 9g 1% Saturated Fat 0. 00g 0% Monounsaturated Fat 0. 7g Polyunsaturated Fat 0. 1g Cholesterol 0mg 0% Sodium 2mg 0% Total Carbohydrates 2. 7g 1% Dietary Fiber 2. 1 g 8% Protein 0. 6g Vitamin A 0% Vitamin C 2% Calcium 4% Iron 5% Source: Sarkar (2012) The precise volatile compounds acting as antimicrobial compounds have not been examined clearly till now, although there are some volatile compounds suggested to be the antimicrobial compound inside coriander which are (2E) – hexenal and (3E) – hexenal (Kubo et al. , 2004).

They are reported to have antimicrobial activity against Gram-negative and Gram-positive bacteria such as Escherichia coli O157:H7, Listeria monocytogenes, and Staphylococcus aureus, which are foodborne pathogenic bacteria. It also exhibits bactericidal activity and is reported to have an effective antibacterial. The mechanism of the activity of coriander is membrane damage causing cell death to the bacteria (Silva et al. , 2011). However, according to Uma et al. (2009), coriander seems to not having an effective antifungal activity and its activity toward yeast have not yet been examined further. 2. 2. 3 Black Pepper

Black pepper (Pipper nigrum) is a condiment that has been used since ancient times and is native to India. Black pepper is useful for treatment of various sicknesses such as vertigo, asthma, fever and also cholera. The volatile oil of black pepper has been shown to have antimicrobial activity as well (Karsha and Lakshmi, 2009). The major antimicrobial compund found in black pepper are monoterpenes and sesquiterpenes (Davidson et al. , 2005). According to Karsha and Lakshmi (2009), black pepper shows strong antimicrobial activity against gram-positive bacteria such as Staphylococcus aureus, Bacillus cereus and Streptococcus faecalis.

Gram-negative bacteria such as Pseudomonas aeruginosa, Salmonella typhi and Escherichia coli are affected as well, although the effect on gram-positive bacteria is better. The mechanism of the antimicrobial activity appears to be loss of control over cell membrane permeability. According to Singh et al. (2004), black pepper has antifungal activity as well as it is effective in stopping the growth of molds such as Fusarium graminearum. Black pepper is also shown to be able to inhibit the growth of yeast such as Candida albicans (Joe et al. , 2009). 2. 2. 4 Potassium Sorbate

Potassium sorbate are currently one of the most widely used preservative and can be used to preserve foods, animal feeds, pharmaceuticals, and cosmetics. Potassium sorbate may be manufactured as a powder or granules and has an antimicrobial potency of 74% compared to sorbic acid. The molecular weight of potassium sorbate is 150. 22 and is the most soluble form of sorbate compared to the others, such as calcium sorbate and sodium sorbate. Besides good solubility, potassium sorbate is also has good stability and easy to manufacture, making it the most used form of sorbate in food industry.

Sorbate is very effective when used against bacteria, molds, and yeasts. Yeasts inhibited by sorbate are Brettanomyces, Candida, Cryptococccus, Debaryomyces, Endomycopsis, Hansenula, Kloeckera, Pichia, Rhodotorula, Saccharomyces, Sporobolomyces, Torulaspora, Torulopsis, and Zygosaccharomyces. Molds species inhibited by sorbate are Alternaria, Ascochyta, Ascosphaera, Aspergillus, Botrytis, Cephalosporium, Chaetomium, Cladosporium, Colletotrichum, Cunninghamella, Curvularia, Fusarium, Geotrichum, Gliocladium, Helminthosporium,

Heterosporium, Humicola, Monilia, Mucor, Penicillium, Phoma, Pepularia, Pestalotiopsis, Pullularia, Rhizoctonia, Rhizopus, Rosellinia, Sporotrichum, Trichoderma, Truncatella, Ulocladium, and others. While for bacteria, the species inhibited are Acetobacter, Achromobacter, Acinetobacter, Enterobacter, Aeromonas, Alcaligenes, Alteromonas, Arthrobacter, Bacillus, Campylobacter, Clostridium, Escherichia, Klebsiella, Lactobacillus, Micrococcus, Moraxella, Mycobacterium, Pediococcus, Proteus, Pseudomonas, Salmonella, Serratia, Staphylococcus, Vibrio, Yersinia, and others (Davidson et al. , 2005). 2. 3

Mechanism of Antimicrobials There exist some mechanisms of antimicrobial activity in inhibiting the growth of microbes. The antimicrobials are classified into: cell wall destructor, cell wall permeability intervention, destructor of proteins, nucleic acids, and enzymes, antimetabolites, inhibitors of nucleic acid synthesis, and cell plasmolysis (Fardiaz and Betty, 1989). Referring to Fardiaz and Betty (1989), the broken cell wall of microorganisms will cause the cell content to depart from the cell and thus, inhibit the cell metabolisms. Severe destructions on the cell may cause the death of the cell.

Lysozyme is one of the enzymes that are able to destruct the cell wall of Gram-positive bacteria. An enzyme produced by a bacterium might be able to inhibit the growth of other microbes. There is also a type of antimicrobials that is able to inhibit the formation of cell wall materials. These cells that do not have cell wall are called protoplast. Protoplast is very easily broken, except when placed in isotonic medium. Penicillin and cycloserin are examples of compounds that retard the formation of peptidoglycan in developing cell. Gram-positive bacteria are susceptible to penicillin as they have lots of peptidoglycans.

The breaking of plasma membrane and leakage of cell content will inhibit the microorganism growth or even kill the microorganisms. The implication if the cell destruction is the enzymes will not be able to function properly in the cell metabolism. However, antimicrobials that intervene the cell wall permeability are rarely used in food industries (Fardiaz and Betty, 1989). Compounds destructing the protein and nucleic acid are able to destroy cells. This type of destruction is unfixable. For instance, certain amount of alcohol and sodium chloride are able to denaturate the proteins.

Those two compounds are often used in food industries (Fardiaz and Betty, 1989). Antimetabolites are the compounds that are similar to natural metabolites. These antimetabolites will interrupt the metabolisms in the cell. The interruption of the metabolisms might retard the cell growth or even kill the cell. Furthermore, the synthesis of DNA and RNA may be inhibited by some antimicrobial compounds, namely the compounds that are able to retard the formation of nucleic acid arrangement and compounds that inhibit the nucleic acid polymerization (Fardiaz and Betty, 1989).

Plasmolysis or the breakage of a cell is caused by the high plasmolysis pressure. Materials that are often used in food to promote the cell plasmolysis are salt and sugar. Salt and sugar are considered to be able to increase the osmotic pressure in food materials therefore plasmolysis takes place (Fardiaz and Betty, 1989). 2. 4 Antimicrobial Sensitivity towards Microbial Defense Microorganisms have the ability to resist some types of antimicrobial substances. There are two types of resistance in microorganisms toward antimicrobial agents, such as intrinsic or natural resistance and acquired resistance.

The antimicrobial agents in intrinsic resistance could not affect the microorganisms, as they have no target sites, which are the microorganisms, to affect. In contrary, in microorganisms that don’t have the intrinsic resistance, the antimicrobial substance could gradually enter the microbial cell and affecting the activity of the microorganisms, as the microorganisms’ cell membrane have lower permeability to antimicrobial substance (Sosa et al. , 2010). Furthermore, in acquired resistance, the microorganisms are naturally vulnerable, as they need specific ways for preventing to be affected by the antimicrobial substances.

Some examples of the specific ways are the presence of enzyme that has the ability to inactivate the antimicrobial agent, or alternative enzyme that has the ability to inhibit the activity of antimicrobial agent. Then, it also happens when there is mutation and post-transcriptional and posttranslational in the microorganisms that are the target of the antimicrobial agent. Thus, these will reduce the binding of the antimicrobial agent (Sosa et al. , 2010). Every microorganism has different sensitivity towards different type antimicrobial agents. Coriander (Coriandrum sativum L. is mostly used as seasoning condiment. According to Kubo et al. (2004), in the leaves of coriander, there are volatile oils that are suggested to have antimicrobial properties against food born pathogen, such as Salmonella species, which are gram-negative bacteria. Black pepper (Piper nigrum L. ) is used mostly in food as seasoning condiments. The aqueous and ethanolic extract of black pepper is very effective for inhibiting antibacterial activity agains penicillin G resistant strain of Staphylococcus aureus, Bacillus cereus and Bacillus subtilis (Chaudhry and Tariq, 2006).

According to Karsha and Lakshmi (2010) experiment, gram-positive bacteria were more susceptible towards antimicrobial in black pepper than gramnegative bacteria. In gram-positive bacteria, the most susceptible towards antimicrobial in black pepper is Staphylococcus and followed by Bacillus and Streptococcus. Furthermore, among gram-negative bacteria, the most susceptible towards antimicrobial in black pepper is Pseudomonas, followed by E. coli, Klebsiella and Salmonella. Garlic (Allium sativum) is commonly used for antifungal, antiviral, antibacterial, antihelmantic, antiseptic and anti-infamatory.

Garlic extract is effevtive in inhibiting the microbial activity of both gram-positive and gramnegative bacteria. Several examples of the gram-negative bacteria are E. coli, Salmonella species and Citrobacter Enterobacter, Pseudomon, Kilabsella) and the gram-positive bacteria are Pseudomonas aeruginosa, Salmonella typhi, Proteus, spp. , Staphylococcus aureus, S. pneumonia Group A streptococcus and Bacillus anthrax (Daka, 2011; Durairaj, 2009). Potassium sorbate is used as preservative in food as the sorbic acid is more effective than benzoic acid in preserving food. The preservation process occurs in higher pH.

It is effective to inhibit the microbial activity of Pseudomonas species, which are categorized as gram-positive bacteria (Beuchat, 1980). Mostly, gram-positive bacteria are more sensitive towards antimicrobial agent than gram-negative bacteria (Torrence and Isaacson, 2003). 2. 5 Factors Affecting Microorganism Strength towards Antimicrobial Compounds The resistance of microbes towards particular antimicrobial compound is dependent on several factors that contained in that particular microbe such as the cell wall, protein content, nucleic acid, and membrane cell (Lay, 2002).

There are several types of microbes that have cell walls, and an antimicrobial compound that can affect the mechanism of the cell wall that influence the microbial resistance. Anti-microbial compounds may interfere with the work of the cell wall as well as peptidoglycan biosynthesis, which is the process in prokaryotic cell wall structure construction. Disruption of peptidoglycan may affect the resistance and sensitivity of microbes to changes in osmotic perspective (Lay, 2002). Microbes also contain nucleic acids.

The nucleic acid can be affected by antimicrobial compunds where the enzymes that are going to be used for the synthesis of nucleic acid are inhibited. The example is rifampin where it binds the enzyme RNA polymerase, quinolone as well as binding enzyme DNA gyrase (Lay, 2002). The resistance of microbes can be affected by the metabolism of the microbes. Enzyme that catalyzes the synthesis of essential molecules can be inhibited by antimetabolite. Antimetabolite is the antimicrobial that is used for inhibiting the growth of microbes. An example of antimetabolite is the sulfinylamide (Lay, 2002).

In general, most living cells including microorganisms has the ability to control what is going in and out of the membrane. If there is a rupture in the membrane, it will cause the spillage of the essential inorganic ions. Thus, rupture in the cell membrane can affect the growth and death of the microbes (Lay, 2002). 2. 6 Methods of Microbial Defense towards Antimicrobial Activity 2. 6. 1 Well Diffusion Method Well diffusion method is done by pouring the microbial suspension that is going to be tested into a sterile Petri dish continued by pouring the media agar into the dish. Then, the Petri dishes are mixed by the eight movement ethod to allow even mixing. The media is then allowed to be solidified and cynlidrical holes are made. The holes are then filled with antimicrobial agents to be tested. The cup was incubated at 37°C for two days and then observed on the antimicrobial activity of the tested microbial suspension. Antimicrobial ingredients poured into the well are able to spread evenly as it can diffuse in all directions around the microbial suspension. Once incubated, usually will form a clean circular zone of microbes. This method can be used to test several different types of antimicrobial agents. (Smith, 2005) 2. 6. Kirby Bauer Disc Method One of the easy methods to test the vulnerability of organisms towards the antimicrobial agents is by inoculating the agar with culture and allowing the antimicrobes to diffuse to the media agar. The discs that contain antimicrobial agents are placed on the surface of the plate that has the organisms that are going to be tested. At particular distance on respective discs, the antimicrobes will diffuse to a point where the antimicrobes are unable to inhibit the microbial growth. Antimicrobial effectiveness is shown by the inhibition zones. Inhibition zone appears as clean areas that surround the disc.

The diameter zone can be measured by using ruler and the result of the experiment considered to be one antibiogram. (Smith, 2005) 2. 6. 3 MIC and MBC The antimicrobial activity can be observed by knowing the concentration of the antimicrobial agents that are going to be used by reducing the total critical number of bacteria that caused their death. MIC (minimum inhibitor concentration) from an antimicrobes can be known by providing the antimicrobial agents into two serial dilutions in series tubes or can be done by well method in a media that has been inoculated with bacteria.

Series tubes that have been filled with antimicrobial agents are incubated to see the growth of the bacteria and the turbidity is observed. The increment in turbidity indicates the growth of the microbes. MIC is the lowest concentration of an antimicrobial agent where the grwoth can be inhibited completely. (Smith, 2005) MBC (minimum bactericidal concentration) is the total number of antimicrobial agents that is required to kill organisms.

MBC is done by taking a part from each serial tubes from the MIC that does not show any growth of the bacteria that has been incubated, The samples is taken from respective tubes that has been incubated in pour plate media. MBC is the lowest concentration of antimicrobial agents that are able to kill at least 99. 9% of the inoculums that has been incubated (Smith, 2005). 2. 7 Food Preservatives Preservatives are commonly used to prevent destruction of physical, chemical and microbiological food. Use of antimicrobial preservatives combined with other preservatives so that the preservation of the food will be maximized.

According Fellows (2000), the criteria for antimicrobial preservative in food are the usage and is more efficient which when dissolved in water, stable in storage, non-toxic, low antimicrobial concentrations but has a wide range, optimum efficiency at room temperature, non-corrosive, odorless, and its high penetrative ability to the food. Based on its mechanism, the antimicrobial agent acts as the rupture of the cell wall When there is a rupture on the cell wall, the cell contents will spill out thus inhibiting the metabolism of cells. The destruction of the cell wall can result in cell death.

Lysozyme can damage the cell walls of Gram-positive bacteria. Penicillin and sikloserin inhibit the growth of peptidoglycan in the cell develops. Gram-positive bacteria is sensitive towards penicillin as the high level of peptidoglycan content. Damage to the cell wall would also cause damage to the plasma membrane (Fellows, 2000). NaCl and alcohol is often used to preserve food because it can cause denaturation of proteins and nucleic acids that can destroy the cell and cannot be repaired. While H2O2 is an antimicrobial that can destroy the enzyme activity of microbes.

Compounds inhibiting the formation of nucleic acids and nucleic acid polymerization inhibitor compounds can inhibit the synthesis of both DNA and RNA. The use of salt and sugar can cause plasmolysis the microbial cell. Since the osmotic pressure on microbial too high, so that the cells undergo plasmolisis and can inhibit the growth of microbes (Fellows, 2000). Ascorbic acid can inhibit the growth of bacteria and molds in a way to inactivate the enzyme fatty acid dehydrogenase. Ascorbic acid can work optimally at a pH above 6. 5.

Propionic acid is at its most effectiveness to inhibit molds and yeasts with maximal activity at pH above 5. Acetic acid as vinegar used to preserve bread in order to prevent mold contamination, but vinegar cannot inhibit the growth of yeasts. Acetic acid work optimally at low pH (acid). Ethylene oxide and propylene oxide can be used as a fumigant in spices and flour. Sodium or potassium nitrite and nitrate are commonly used for preservatives in meat products. Maximum working power of nitrite compounds is pH of about 57. Nitrite also serves to inhibit Clostridium botulinum, Acinetobacter, Moraxella, Flavobacterium,

Pseudomonas, Enterobacter, Escherichia, and some micrococcus. Nitrites are heated simultaneously with foods will provide the growth inhibitory effect against microbes ten times greater than that of nitrite without heating (Fellows, 2000). CHAPTER III MATERIALS AND METHOD 3. 1 Materials and Equipments Equipments that are used in the experiment are balance, blender, grater, dilution bottle, autoclave, waterbath, refrigerator, vernier caliper, tip with the cuttop, sterile toothpicks, sterile petri dishes, micropipette, tip (10 ml and 100µl), and Bunsen’s burner.

Materials that are used are spices (black pepper, garlic, and coriander), potassium sorbate, alcohol, aquadest, bacteria culture (Bacillus subtilis), yeast culture (Candida tropicalis), mold culture (Aspergillus oryzae), PCA media, and NA media. 3. 2 Procedures 3. 2. 1 Extract Preparation 1. Spices were weighed up to 3 grams and reduced in size. 2. The spices were mixed with 10mL of ethanol into Erlenmeyer flasks. 3. 2. 2 Antimicrobial Assay 1. 1mL of culture is added into Petri plate 2. The matching medium is added into the Petri plates (NA for B. subtilis and PDA for A. ryzae and C. tropicalis) 3. The media were let to solidify. 4. Holes were made by using tips with cut-tops. 5. Mixtures of spices were added into the holes. 6. The plates were incubated were incubated for 48 hours in 37? C. CHAPTER IV RESULTS AND DISSCUSION 4. 1 Effect of Antimicrobial Compounds Towards Microbial Growth 4. 1. 1 Garlic Table 4. 1 Observation result of inhibitory activity by garlic From Table 4. 1, it can be seen that the microorganism that was the most susceptible to allicin contained in garlic, judging by the largest area inhibition, was Bacillus subtilis.

There were even no growths in some Petri dishes that meant that the effectiveness of allicin as the antimicrobial compound could be found most when it was applied for bacteria, which was Bacillus subtilis in particular. It matched with the previous literature discussed stating that allicin is an active compound in garlic that attacks the cell membrane in microorganism. However, there was an error found in the experiment from Group 4, which resulted in no inhibition found from Bacillus subtilis. This might happen due to the absence of the allicin itself or the ontamination happened which might result in the building of the resistance towards antimicrobial compound. Afterwards, it can be seen from the experiment that Candida tropicalis and Aspergillus oryzae shared almost the same result, which means that they were also susceptible to allicin. The uneven inhibition found in Candida tropicalis showing the largest inhibition (7. 23mm) beyond the inhibition done for Bacillus subtilis might happen because of the uneven diffusion of the active antimicrobial compound to the dishes. It still matched the theory since allicin has antibacteria and antifungal activity towards the species mentioned above.

From the result, it can be concluded that garlic can be used as the antimicrobial compound in food to prevent foodborne disease and food poisoning. However, the concentration of garlic has to be concerned since it has strong odor and may be unpleasant to some people. 4. 1. 2 Coriander Table 4. 2 Observation result of inhibitory activity by coriander From Table 4. 2, it can be seen that coriander is found to be effective as an antimicrobial compound most in Bacillus subtilis, although some of the dishes showed no area of inhibitions.

The disappearance of Bacillus subtilis in most of Petri dishes shown by no growth sign indicated that coriander worked best to inhibit bacteria. This result matched with the previous literature stating that coriander inhibits food pathogenic bacteria, especially Gram-positive bacteria. However, coriander has the least inhibition activity towards Candida tropicalis and Aspergillus oryzae was found to be less susceptible to the volatile compound in coriander acting as antimicrobial compound. There were almost no area of inhibition found in every petri dish, proving that coriander did not affect mold and yeast.

Since the literature stated that coriander has almost no antifungal activity and its activity toward yeast has not been examined, the result matched them. 4. 1. 3 Black Pepper Table 4. 3 Observation result of inhibitory activity by black pepper From the result of the experiment, it can be seen that black pepper is most effective when used against Bacillus subtilis, as many bacteria were inactivated, indicated by the area of clear zone, which in some plates, all of them doesn’t grow at all and so the area of clear zone can’t be measured.

Aspergillus oryzae are quite susceptible as well to black pepper’s antimicrobial compound as the area of inhibition overall is large. While the most resistant microorganism from the experiment shown is Candida tropicalis, as the area of inhibition is relatively small. From the theory, black pepper shows antimicrobial activity against bacteria, molds, and yeasts, but the strongest towards bacteria, especially Grampositive bacteria. The result of the experiment matches the theory, as black pepper is very effective in stopping the growth of Bacillus subtilis, which is a Grampositive bacterium.

It also inhibited the growth of Candida tropicalis and Aspergillus oryzae, so the result of the experiment matches the theory. 4. 1. 4 Potassium Sorbate Table 4. 4 Observation result of inhibitory activity by potassium sorbate From the result of the experiment, it can be seen that potassium sorbate is very effective in stopping the growth of Bacillus subtilis, as in some plates it inhibited the growth of all the bacteria and so the area of clear zone can’t be measured. Antimicrobial activity can be seen as well towards Candida tropicalis and Aspergillus oryzae.

According to the theory, potassium sorbate is very effective when used to inhibit the growth of bacteria, molds, and yeasts. The result of the experiment matches the theory, as potassium sorbate in this experiment is able to stop the growth of Bacillus subtilis, Candida tropicalis, and Aspergillus Oryzae. 4. 2 Microbial Defense Towards Antimicrobial Compounds 4. 2. 1 Bacteria (Bacillus subtilis) Table 4. 4 Table of diameter of inhibition zone of Bacillus subtilis in some condiments From the table 4. 4, it is shown that the most effective condiment in affecting the microbial defense of the Bacillus subtilis for its growth is arlic. Also, the least effective condiment for inhibiting the growth of Bacillus subtilis is coriander. According to the theory, garlic is effective for both Gram-negative and Grampositive bacteria, thus the inhibition zone is larger. Also, coriander is effective in inhibiting Gram-negative bacteria, as in the experiment the bacteria used was Gram-positive bacteria, thus, coriander is not effective in inhibiting Bacillus subtilis. The experiment result has shown the same result as the theory given. 4. 2. 2 Yeast (Candida tropicalis) Table 4. 5Table of diameter of inhibition zone of Candida tropicalis in some condiments

In the table 4. 5, it shown that the most effective condiment in affecting the microbial defense and microbial growth of Candida tropicalis is garlic and the least effective is coriander. According to the theory, garlic is used as antifungal and is the most effective one in inhibiting the growth of bacteria, molds and yeast. Thus, the inhibition zone of garlic is the largest. Also, as coriander is mostly effective in inhibiting Gram-negative bacteria, the rate of inhibition of yeast is lower, so the inhibition zone is smaller. The experiment result has shown the exact result as the theory given. 4. 2. Molds (Aspergillus oryzae) Table 4. 6 Table of diameter of inhibition zone of Aspergillus oryzae in some condiments The experiment result has shown that the most effective condiment towards the inhibition zone in Aspergillus oryzae media is garlic and the least effective condiment is coriander. Referring to the theory, garlic is mostly used as antifungal and the most effective condiment used in the experiment to inhibit the growth of bacteria, mold, and yeast. Also, coriander is least effective in inhibiting the growth of Aspergillus oryzae as coriander is most effective in inhibiting gramnegative bacteria.

In conclusion, the result of the experiment shows the same result as the theory given. CHAPTER V CONCLUSION Spices have different antimicrobial compounds able to inhibit the growth of various types of microorganisms. Based on the experiments, garlic, coriander, and black pepper have the most effective activity in inhibiting the growth of bacteria, or in this case Bacillus subtilis. However, coriander was proven to have no antifungal activity by the absence of inhibition zone on the Petri plates with yeast and molds, in this case Candida tropicalis and Aspergillus oryzae.

In addition, potassium sorbate is effective to inhibit the growth of all types of micoorganisms in the experiment: bacteria, yeast, and molds. The Bacillus subtilis bacteria, Candida tropicalis yeast, and Aspergillus oryzae molds are most susceptible by the presence of garlic. This means that the garlic has the highest effectiveness in affecting the defense of bacteria, yeast, and molds. In contrast, the growth of bacteria, yeast, and molds is least affected by the presence of coriander.

Free Essays

Ib Biology Hl

Is the neural pathway significantly longer for a visual stimulus or a sound stimulus (or a pressure stimulus) Data collection and processing Table 1a: Data collected by John Rha and Arthur Hamilton by dropping ruler for calculation of length of the neural pathways (Visual, Auditory and Sensual) Trial#| Visual| Auditory(Sound)| Sensual(Pressure)| | (cm±0. 1cm)| (cm±0. 1cm)| (cm±0. 1cm)| | John| Arthur| John| Arthur| John| Arthur| 1| 43. 9| 24. 1| 33. 1| 34. 6| 50. 1| 50. 5| 2| 73. 7| 45. 6| 66. 1| 49. 2| 29. 2| 75. 2| 3| 47. 4| 31| 80. 2| 25. 3| 54. 4| 41| 4| 32| 24. 7| 23. 1| 39. 6| 25. 6| 47. 4| 5| 23. 5| 29. | 32. 9| 35. 1| 26. 2| 30. 8| 6| 38. 6| 27. 6| 47. 6| 34. 7| 40. 6| 49. 5| 7| 37. 9| 20. 9| 56| 21. 7| 41. 5| 40. 2| 8| 28. 2| 22. 7| 24| 57| 29. 1| 62| 9| 39. 9| 62| 43. 6| 87. 2| 30. 6| 35. 4| 10| 23. 6| 30. 5| 49. 3| 44. 4| 44. 2| 78. 2| 11| 58. 4| 26. 2| 66. 8| 24. 2| 41. 9| 84. 3| 12| 40| 32. 7| 21. 1| 36. 1| 14. 2| 21| 13| 55. 5| 20. 2| 61. 7| 15. 1| 61| 41. 3| 14| 39. 6| 32. 2| 46. 9| 28. 58| 65| 24. 8| 15| 46. 1| 18. 1| 61. 7| 55| 45. 9| 22. 3| Table 1b: Calculations of the reaction times the meter stick fell Trial#| Visual| Auditory(Sound)| Sensual(Pressure)| | John| Arthur| John| Arthur| John| Arthur| | 0. 299319| 0. 221774| 0. 259906| 0. 26573| 0. 319758| 0. 321032| 2| 0. 387825| 0. 305059| 0. 367285| 0. 316872| 0. 244114| 0. 391752| 3| 0. 311022| 0. 251526| 0. 404566| 0. 227228| 0. 333197| 0. 289264| 4| 0. 255551| 0. 224518| 0. 217124| 0. 284282| 0. 228571| 0. 311022| 5| 0. 218996| 0. 243696| 0. 259119| 0. 267643| 0. 231234| 0. 250713| 6| 0. 28067| 0. 237332| 0. 311677| 0. 266113| 0. 287849| 0. 317837| 7| 0. 278113| 0. 206526| 0. 338062| 0. 210442| 0. 291022| 0. 286428| 8| 0. 239898| 0. 215236| 0. 221313| 0. 341067| 0. 243696| 0. 355711| 9| 0. 285357| 0. 355711| 0. 298294| 0. 421852| 0. 249898| 0. 68784| 10| 0. 219461| 0. 249489| 0. 317194| 0. 301019| 0. 30034| 0. 399489| 11| 0. 34523| 0. 231234| 0. 369224| 0. 222234| 0. 292421| 0. 414778| 12| 0. 285714| 0. 258331| 0. 207512| 0. 271429| 0. 170234| 0. 20702| 13| 0. 336549| 0. 203038| 0. 35485| 0. 175546| 0. 352831| 0. 29032| 14| 0. 284282| 0. 256348| 0. 309377| 0. 241509| 0. 364216| 0. 224972| 15| 0. 306727| 0. 192195| 0. 35485| 0. 33503| 0. 306061| 0. 213331| Table 1c: Calculations of the length (distance) of neural pathway Trial#| Visual| Auditory(Sound)| Sensual(Pressure)| | John| Arthur| John| Arthur| John| Arthur| 1| 2993. 19| 2217. 739| 2599. 58| 2657. 296| 3197. 576| 3210. 315| 2| 3878. 249| 3050. 594| 3672. 846| 3168. 725| 2441. 144| 3917. 517| 3| 3110. 22| 2515. 26| 4045. 658| 2272. 282| 3331. 973| 2892. 637| 4| 2555. 506| 2245. 176| 2171. 241| 2842. 821| 2285. 714| 3110. 22| 5| 2189. 959| 2436. 96| 2591. 194| 2676. 428| 2312. 345| 2507. 133| 6| 2806. 698| 2373. 321| 3116. 775| 2661. 134| 2878. 492| 3178. 371| 7| 2781. 132| 2065. 262| 3380. 617| 2104. 417| 2910. 221| 2864. 277| 8| 2398. 979| 2152. 36| 2213. 133| 3410. 668| 2436. 96| 3557. 114| 9| 2853. 569| 3557. 114| 2982. 945| 4218. 521| 2498. 979| 2687. 841| 10| 2194. 613| 2494. 93| 3171. 943| 3010. 187| 3003. 399| 3994. 895| 11| 3452. 299| 2312. 345| 3692. 242| 2222. 336| 2924. 213| 4147. 78| 12| 2857. 143| 2583. 306| 2075. 12| 2714. 286| 1702. 339| 2070. 197| 13| 3365. 491| 2030. 381| 3548. 498| 1755. 458| 3528. 311| 2903. 2| 14| 2842. 821| 2563. 48| 3093. 773| 2415. 089| 3642. 157| 2249. 717| 15| 3067. 273| 1921. 946| 3548. 498| 3350. 297| 3060. 612| 2133. 312| Table 2a: Average distance of neural pathway Trial#| Visual| Auditory(Sound)| Sensual(Pressure)| | John| Arthur| John| Arthur| John| Arthur| | 2889. 8| 2434. 7| 3060. 2| 2765. 3| 2810. 3| 3028. 3| Conclusion and evaluation

The objective of this experiment was to determine the distances of neural pathways and to discover if there are any significant differences between Visual, Auditory and Sensual neural pathway distances. The distance of each neural pathway includes and displays the following procedures. Ex) Visual stimulus: First, your eye sees the ruler. Then, your eye sends a message to the visual, stimulus cortex, which sends a message to the motor cortex. The motor cortex sends a message to the spinal cord. The spinal cord sends a message to the muscles in your hand and fingers. Finally, your muscles contract to allow you to catch the ruler.

John’s data shows that there were no significant differences. However, Arthur’s data shows that the neural pathway for pressure stimulus is significantly longer than the pathway for visual stimulus. This is shown by the calculated pathway length and the t-test performed. Calculation: The algorithm to calculate the reaction speed is d = vt + ? at? where d = distance in meters v = initial velocity = 0 a = acceleration due to gravity = 9. 81m/s? t = time in seconds We need to manipulate d = vt + ? at? to give us an algorithm for t As v = 0 then vt = 0 therefore the algorithm is t = sqrt(2d/a) Example d = 43. 9cm = sqrt((2 ? 43. 9 ? 9. 8)) t = 0. 299 seconds (sigfig) 0. 299319*10000(m to cm)=2993. 2cm or 29. 932m The calculated distance for Arthur’s Visual stimulus was 2434. 7cm, which was much shorter than the pressure stimulus length of 3028. 3cm or the auditory stimulus length of 2765. 3cm. The t-tests performed showed that there were no significant differences for John’s data, but Arthur’s data showed that the three sets of data were all significantly different. One huge weakness of this lab was that John and Arthur’s hands were not the same distance away from the ruler for every trial. This could have led to incorrect data ollection. There was another weakness when we were collecting the pressure stimulus, because the ruler fell more slowly due to the friction between the palm and the ruler, giving the appearance of a faster reaction time. Also, the auditory reaction time was higher than the visual reaction time because the voice of the other person was not perfectly in time. Another reason for this is that it had lots of variability when the person commanded the other person to “Go! ” Our group could have attached another ruler on the sidewall to ensure a constant distance between the hand and the dropping point.

Therefore, to improve this lab, we have to keep the distance between the hand and ruler constant for all trials. Also, when the person says “Go! ” it also takes reaction time from his brain to his fingers to drop the ruler and from his brain to his oral muscles to speak “Go! ” Therefore, to improve this lab, we need to use an electronic device that can automatically drop the ruler with a short “beep” sound. To decrease friction, we need to use a simple grabbing tool like tweezers instead of just grabbing with our hand, which creates sliding or friction depending on the hand’s condition (wet or dry).

Free Essays

Examiner Tips for Igcse Biology 0610

EXAMINER TIPS for IGCSE Biology 0610 How to use these tips These tips are based on some common mistakes made by students. They are collected under various subheadings to help you when you prepare for your examinations. • • • • • Make sure you read all the general tips. These can be important in any of the papers you do. Make sure you know which examination papers you are taking before you look at the tips for the different papers All of you will take paper 1, which is all multiple choice questions. You may be taking paper 2, which is Foundation OR you may be taking paper 3, which is Extended.

You may be taking paper 5, which is a practical examination in a laboratory OR you may be taking paper 6 which is a written paper about practical work. General Advice • Answering questions. The questions are meant to let you show the biology you know. There are no trick questions. When you are writing your answers remember that another person has to be able to read it. o o o o o o o o Do not waste time by writing out the question before you start to answer. Keep your handwriting clear and legible. Keep you answer in the lines on the question paper.

If you write in the margin, at the bottom of a page, or on blank pages, part of your answer might be missed. If you have to cross out something, put a line through, but do not scribble all over it. If you have to use a different space to write another answer to one you have crossed out, then put a note to say where it is, e. g. answer on page 5 Written papers are now marked on computer screen so your written paper will be scanned. If you write on the margin the scanner may not be able to copy this. Try to be precise, in other word be accurate in what you say.

Using biological terms correctly can help. Do not use word like “it”, “they”, “effect”, “affect” without any more explanation. A sentence like “It has an effect on the body” or “They affect the process” does not say anything. – If you use the word “it” or “they “– think WHAT? – If you use the word “affect” or “effect” – think HOW? – e. g. State why magnesium ions are important for healthy plant development. [1] – “it are needed by the plant” is true but too vague. – “They are needed by the leaves” is still too vague – Ask yourself: What is it or they? What is the “need”? “Magnesium is needed to make chlorophyll” is a better answer – “Magnesium is part of a chlorophyll molecule. ” Good answer! • Terms. These are the names used in biology. These will be used in questions. You will get more marks if you can use them correctly in you examination. Ask your teacher if you are unsure of the different meanings between biological terms. o o Try to use the correct spelling. The person marking your answer will try to recognise what word you mean, but if the spelling is too wrong, then they cannot allow you a mark. Some biological terms have very similar spelling.

One example is “ureter”, urethra” and “uterus”. If your mis-spelling is “uretus”, it could be “ureters” or “uterus”. Other common examples are ovum, ova, ovary and ovule, testes and testa; sucrose and sucrase. Do not try to mix the spellings of two words when you are not sure which of them is the correct answer, e. g. meitosis, when you are not sure whether the answer is mitosis or meiosis, or urether, when you are not sure if the answer is ureter or urethra. You need to check carefully that you have used the right word when similar terms are used in the same topic , e. g. urea and urine, ureter and urethra. semen and sperm o o • Writing in you own words. You sometimes have to write two or more sentences to answer a question. o o Use short sentences. If you write long sentences you can get mixed up. It is hard to find correct statements in a muddled answer. You are often asked to write down something you have learned. Make sure you have learnt the meanings of the common terms used in biology, e. g. photosynthesis, osmosis, fermentation. In the revision checklist there is a list of the terms which you should be able to “define”. You also need be able to write down the meaning of more complicated ideas, e. g. evel of organisation, natural selection, global warming, eutrophication. o What you should look for in a question 1) • • • • • The number of marks. In multiple choice questions there is only one mark for a correct answer. Other sorts of question show how many marks at the end of each part like this [2]. The number of marks helps you decide how much to write. The number of marks is a guide to how long to spend on each question or parts of a question. If you allow about 1 minute per mark then you should finish in time to check your answers. Do not waste time and write long answer for a question which has [1].

You will only get one mark even if the rest of the answer has correct statements. If there are two or more marks do not write the same thing in two different ways, e. g. The leaf is very large. The leaf has a large surface area. The instructions. These are called command words and tell you what to do. If a question says “Show your working” when you have to do a calculation, then write down the stages of your calculation to show how you got your answer. Even if you get the final answer wrong, you may be given a mark for knowing what to do. If a question asks you to “Name” or “State” two things only the first two will be marked.

Use the numbered lines for your answers if they on the question paper. If you write more than two and the first is correct but the second one is wrong, you will only get the mark for the first one. Even if the third answer is correct, it will not be marked. Some questions have two commands in the question, for example “Predict” AND “Explain” …. ” This means you have to say what you think will happen AND then say why you think it will happen. The Revision Checklist has a list of terms used in biology papers to tell you what to do in an answer (section 4. 3 Command words and phrases).

Make sure you know what these terms mean. e. g. “Name the process by which green plants make sugars”, all you need to write for your answer is “Photosynthesis”. A question which asks you to “Define photosynthesis”, would expect you to write one sentence such as “The process by which green plants use light energy to make sugars”. What the question is about. Make sure you know which part of your biology is being tested Read the whole of a question carefully before you begin to answer it. Some of the parts have similar answers so you need to work out the difference between them.

If you write exactly the same thing in different parts of the same question, then only one of them might be a correct answer. It helps to highlight the main features of a question. e. g. “Name the tissue that transports the sugars made by photosynthesis to other parts of the plant”. This tells you that you want a one word answer, about plant transport of sugars. Do not be put off the question is about something you have not studied. There will be enough information in the question for you to work out an answer. 2) • • • • • 3) • • • • • • • • • •

Look carefully at any diagrams, graphs or tables and make sure you understand what they are about. You may have to use information from them to answer the questions. Answer each question as far as you can. Do not spend a long time staring at a question If you have forgotten something, go on to the next question or part of a question. Come back to the ones you found difficult when you have finished all of the paper. Try not to leave blanks. When you come back to a question you often remember an answer you left out. Do not waste time by writing about things unrelated to the question. Paper 1 Tips • Each question tests just one thing.

You have about 1 minute to read and answer each question. o Some questions test what you know and understand. For example “What part of the eye detects light? ” o Some questions test if you can use what you have learned to understand new data. These questions will often have a diagram, graph or table to use. Try to decide what the question is testing as you are reading it. o To answer a question that asks “What is a characteristic feature of all living things? o You need to know the characteristic features of living things. If you know a quick way of remembering all seven then you can jot it down on the question paper. . g. MRS GREN for Movement, Respiration, Sensitivity, Growth, Reproduction, Excretion and Nutrition, or the first letters of Real Elephants Grow Massive Red Feet Slowly, o To answer a question that has a diagram of the circulatory system and asks “In which vessel will absorbed alcohol first be found? “. You need to think about what the question is asking you. – Is it about digestion? – Is it about excretion (of alcohol)? – Is it about the circulation? The question is asking about something absorbed from the gut to be transported, so it is about circulation. – Which vessel carries substances absorbed by the gut? Answer “The Hepatic Portal Vein”. So you have to choose the letter which labels the hepatic portal vein. Do not try to find a pattern in the letter order of correct answers. o The same letter could be the correct for several answers in a row. o Letter A might be the correct answers for more questions than are B, C or D. Or there could be fewer correct answers shown by letter D than any of the others. o Do not let what you have chosen for the previous questions influence what letter you choose. • • Written Paper Tips • You should read all of a question before you begin to answer it.

Different questions will ask you to do different tasks to test how well you know and understand biology. o The topic is usually the same for all different parts of the question. Remember that underlining important words will help you to be clear about what you are being asked to do. o Look for clues in the words of the question. If you see “mammal” you know that the animals are warm blooded and have biological systems like ours. o If you are only given a Latin name or a name you do not recognise, e. g. “dik-dik”, look to see if you are told anything about it. If you are told it is a herbivore, then you know it eats plants.

The main sort of tasks you might be asked to do are: • Identify features of cells, tissues organs. For example, “label on Fig. 5. 1 using labelling lines, a petal, a sepal and a stamen. To answer this question o You have to know the structure of a flower. o You also have to be able to find the structures on a diagram of a flower you may never have studied. o You then have to draw a label line to the structure and write the name next to the labelling line. If you do not draw a label line, or use and arrow, you may not get any marks even if you have found the correct structures.

Use information given in the question. For example if a question asks you to “Use examples from” or “Use only this information” or “With reference to Fig. 6. 2” . . . STOP and THINK! Find out what you are expected to use as examples or get information from. You will not get any marks if you use examples from somewhere else. The information can be given to you in different ways: o Diagram like a food web, a set of apparatus or biological structure. o A graph, which could be a line graph, a bar chart or a histogram. Check the headings and units carefully o A table.

Check the headings and units carefully o You may have to give examples to show that you understand an idea in Biology. – After a diagram of a food web you might be asked to “Name an organism from this food web that is a primary consumer, a tertiary consumers and a producer”. – To answer this question you have to know definitions of producers, primary consumers, tertiary consumers. Then you have to show that you understand how these terms apply to the food web shown in the diagram. If you put examples from other food webs you have learned, you will not get any marks.

After a diagram of leaf structure you may be asked to “Describe and explain the advantage of the distribution of chloroplasts shown in Fig. 8. 1” – To answer this question you have to observe the diagram and describe which cells have the most chloroplasts. Then you have to work out why this arrangement might help photosynthesis. If you write answer about what chloroplasts do you will not get any marks. Draw or interpret graphs. If you are asked to draw a graph: • • • • • Choose a scale which uses most of the grid. Choose a simple scale, e. g. one small square is equal to 1 or 2 or 10 units in the data.

Do not give make it hard for by having to multiply each item in the data by 2/3! o Write the name of the axes and their units, e. g. rate of water loss/ g per h , temperature/ o C, time/ s o Plot the points exactly using a sharp pencil. Draw the points lightly so that you can rub them out if you need to. Make them more definite when you are sure they are right. o Use a cross (x) or a dot in a circle ( ) for your plot points. o Join the points with a “line of best fit or a zig -zag line. o Remember that all curves do not have to pass through the point where the two axes meet. Do not extend you graph beyond the plotted points. If you are asked to read figures from a graph: o Make sure you work out the scale. o Make sure you read from the correct axis and put in the units. o If you are asked for a trend or pattern, describe the overall change, e. g. the line increases and then levels. off. Do not describe each point of the graph. Draw or interpret tables If you are asked to draw a table o Use a ruler and a pencil to draw the table. o Write headings for each column or row of the table. 3 o Write in units if they are needed, e. g. volume of water/cm , mass of seed/g. Do not put units in the table spaces where you write numbers. Do calculations. If you are asked to do a calculation: o You may have to find the figures from a table or graph. o Make sure that you show the units in the calculation. o Show you working. o If you use a calculator, round up the figures to the same as in the question – do not copy all the figures after the decimal point, e. g. If the question figures are 5. 6, 4. 6, then your answer should only have one number after the decimal point. Show or complete equations. You do not have to know chemical symbols for equations of the processes in biology.

But it will help you to understand them if you do. o If you are asked to give either a word or a symbol equation, do not combine symbols and words in the same answer – If you have to give the word equation for anaerobic respiration by yeast, write: o o Glucose > carbon dioxide +ethanol + energy If you have to give the chemical equation for anaerobic respiration by yeast, write C6H12O6 > 2C2 H5 OH + 2CO2+ energy Do not write something like glucose > CO2 + ethanol and energy • Make comparisons. If you are asked to compare two things make sure you make it clear which you are talking about. A question may give to table of data and then ask you about it. Make sure you only use information from the table. e. g. in a table of the composition of normal breast milk and colostrum, you can see which milk contains more fat, protein and sugar. Your answers should start with “colostrum has more …….. than breast milk” or “breast milk has more …… than colostrum”. Do not put “it has more protein. ” The person marking cannot guess which you thought had more protein. o The question may ask you to make a comparison about biology you have learned. e. g. the differences between arteries and veins.

The clearest way of answering is to make your own table. Make sure the headings are clear. Keep the comparisons of the same feature together. Artery has thick wall thick muscle layer vein has thin wall very thin muscle A table like the one below will not get any marks as there are no comparisons of the same features. Artery thick wall no valves • veins elastic layer small amount of muscle Extended writing. This means writing several sentences together. e. g. Suggest what happens if excess nitrogen fertiliser is washed into a stream or pond [4] o The mark scheme used for a question like this will have a list of oints that the person marking your answer will use. o There will be more points than there are marks, so you do not need to put them all in your answer. The points for this question could be: – Algae and aquatic plants grow faster using the fertiliser. – Algae cover the water surface. Light cannot pass to aquatic plants lower down. – These plants die. Bacteria of decay feed on the dead plants. – Bacteria increase in numbers. – These bacteria are aerobic. – They use up more oxygen. – There is not enough oxygen for other organisms which live in the water. – These organisms die. The process is called eutrophication. If your answer is something like “The fertiliser causes low oxygen and it affects animals in the water. ” you will not get any marks. The answer is much too vague, in other words it is not precise. I your answer is something like “The animals do not have enough oxygen for their respiration and they die. ” you will get some marks. Paper 2 tips • • • • • • Most of the questions are short answers. This means that you writing mainly one word or one sentence answers worth one mark. [1]. Longer answers will need two or three sentences. Check the number of marks.

Check the number of command words, do you have to do one or two things. Use the lines given. Do not write too much. Check if you are asked for an actual number of answers. Only give that number. Use the numbered lines and give one answer per number. There will be a few parts of questions that need extended writing. These will have four [4] or [5] marks. The question will often be related to some information you are given. You will need to write four or five sentences in an order that makes sense. You can think of it like “telling a story”. Remember to refer to any information you are given.

Paper 3 tips • • • • • There is more to read in this paper. Many questions will be one, two or three sentence answers. Check the number of marks. Check the number of command word – do you have to do one or two things Check if you are asked for an actual number of answers. Only give that number. Use the numbered lines and give one answer per number. There are questions that may start in one part of the syllabus and link to another, e. g. the information could be about the animals in a particular habitat and what they eat. The first parts of the question might be about the food chains or food webs which include these animals.

Another part of the question could be about the structure of one of the animals or about factors in its environment. You are likely to have questions about events and situations that are new to you. Do not be put off. The question will tell you all you need to know. What you need to do, is show that you can connect the biology you have learned with the new facts. e. g. you may not have learned anything about how cats inherit the length of their fur. o The question tells you that the alleles for fur length are co-dominant. o The question tells you the fur length of pure bred parents are long and short. You know that the offspring of cross breeding are heterozygous for fur length. o You know from your genetics lessons that for features controlled by co-dominant alleles, both alleles are expressed in the offspring. o You know enough to work out that the fur length of the offspring will be medium length. You are likely to be asked to interpret unfamiliar data, e. g. result from an experiment you may not have carried out or could not be carried out in a school. Do not be put off. Follow the same rules as before. There will always be enough information in the question for you to answer it. • •

General Tips for Practical Papers • • • • Look to see how many marks are given for each question. Divide the time of your examination in proportion to the marks given. Whichever paper you do the same rules for recording observations. Use the same rules as in the tips for written papers for tables, graphs, calculations and comparisons. Recording your observations • You can record as: o statements in writing o as tables o drawings • Neat work helps to keep you calm and feeling in control. • Use all the space available on the paper for your observations. • Do not write an explanation until the question asks for one. • Use a sharp HB or B pencil.

It can be rubbed out easily if you need to correct a mistake. • Don’t forget headings for the columns and the rows or tables or graph axes. Don’t forget the units! • Make drawings as big as the space allows. • Use a ruler for labelling lines. • Label in pencil. Planning investigations Some times you are asked to suggest a way of carrying out an investigation or to improve the method that is in the question paper. • When you read through an investigation try to work out three main things: 1. What is being changed – this is called the independent variable, e. g. light 2. What is being measured – this is called the dependent variable, e. . oxygen given off by plant 3. What is being kept the same – these are called the standard or control variables, e. g. type of plant, number of leaves on the plant, environment of plant ,the apparatus used, time for collecting oxygen. • Some investigation needs to have two parts: o the experimental- which is the apparatus used to measure the process being studied and contains the living organism being tested. o The control. –which will be exactly the same as the experiment except the living organism will be missing or replaced by something non-living. e. g. there would be no plant in one set of apparatus. The control shows that the results are due to the activity of the living organism and is not due to the apparatus or an environmental factor. Tips for paper 5 In paper 5 you are following instructions, using laboratory equipment, making observations, recording results and drawing conclusions. • Start by reading the entire first question. • Think about the apparatus needed for each step and imagine using it in your mind. • Check the time to be allowed and imagine following the instructions. • Do the same when you are ready to begin the next question. Following the instructions • Follow the instructions for practical methods exactly.

If you make a change in the method you can alter the results. • Do not take short cuts. • Always label test tubes and other containers to help you remember which is which. • If you are told to “Wash the apparatus thoroughly after each use” make sure you do. If there is anything left in the apparatus the next stage may not work. • If you have to measure a specimen make sure you draw a line on your drawing to show where you made our measurement. • You will get marks for following instructions accurately. Recording your observations • Do not forget that observations can be seen, heard, felt and smelled. • e. g. olour, fizzing, warming, smell of a flower, texture (feel) of a fruit. • You can always something to observe, so make sure you record something for each observation. • Write down exactly what you observe. • e. g. if you add a drop of iodine to a drop of starch solution on a white tile, the colour changes. o You should write “the colour changed from yellow to black. ” o If you write “it turned black” you have not given all the information. o If you add iodine to a drop of water on a white tile. o You should write down ‘the colour stayed yellow. ’ o If you write ‘the colour stayed the same’, or ‘no change’, you have left information out.

Conclusions • Use your own results for your conclusions. • Do not write the conclusion you have learned from a class experiment or from theory. E. g. in an investigation you test drops of a mixture of sodium chloride, amylase and starch solution with iodine once a minute for eight minutes. Then you repeat this with a mixture of water, amylase and starch solutions. o The blue/black colour might disappear sooner in one test tube than the other. o Even if you know that sodium chloride usually makes amylase work faster, you must write down the results from YOUR investigation. You must draw conclusions from YOUR results. o If the colour in both tubes changes at the same time, the conclusion has to be that the sodium chloride made no difference. That is the correct conclusion drawn from your observations. Tips for paper 6 In this paper you are making observations from information given in the paper, recording results and drawing conclusions. Try to imagine doing the practical which has produced the results in the questions. Recording observations • All of your observations are either measurements that you make or diagrams on the paper. • Write down exactly what you see.

Making measurements • Make your measurements as accurate as you can. Measure to the nearest unit e. g. mm. Do not try and “guess” 0. 5mm. • Make sure you put units! • If you have to make calculations use the blank pages within the paper. Do not write in the margin. • Write neatly and show your working. The person marking your paper might be able to give you marks for knowing what to do if you make a mistake or do not finish the calculation. Conclusions • Use your measurements or observations or on the results given in the question for your conclusions. • Do not rely on something you have learned as “the right answer”.

Free Essays

Microbiology Study Guide Unit 2

Define metabolism: The sum of all biological chemical reactions inside a cell or organism Differences in catabolism and anabolism: Catabolism is an enzyme-regulated chemical reaction that releases energy. Complex organic compounds such as glucose, amino acids, glycerol and fatty acids are broken down into simpler ones. The energy of catabolic reactions is used to drive the anabolic reactions. Anabolism is also enzyme regulated but requires energy for taking the simpler broken down components from the catabolism phase and building them into complex molecules such as starch, proteins and lipids What is the role of ATP?

ATP is the driving force for catabolic and anabolic reactions. ATP stores energy that is produced from the catabolic reactions which is later released to drive the anabolic reaction and other cellular work. ATP is stored energy in cells (phosphate groups held together by high energy reacting bonds) ATP is required for synthesis and some of the energy is given off as heat What are enzymes and their components? Enzymes are biological catalysts (substances that speed up a chemical reaction without themselves being permanently altered) Components:

Apoenzyme is the protein portion of an enzyme. Inactive by themselves, must be activated by cofactors Cofactor- non protein portion (IE: ions of iron, zinc, magnesium and calcium) ****If the cofactor is an organic molecule, it is called a coenzyme Holoenzyme- The apoenzyme+cofactor forms the holoenzyme. It is the active enzyme. If you remove the cofactor, the apoenzyme will not function. **Cofactors may assist the enzyme by accepting atoms removed from the substrate or by donating atoms required by the substrate. Substrate=the specific substance that an enzyme will act on) **The crucial function of enzymes is to speed up biochemical reactions at temperatures that are compatible with the normal functioning of the cell. What are metabolic pathways? The sequence of enzyme catalyzed chemical reactions within a cell. What is the Kreb’s cycle? A pathway that converts two-carbon compounds to CO2, transferring electrons to NAD+ and other carriers; also called tricarboxylic acid (TCA) cycle or citric acid cycle A series of biochemical reactions in which a large amount of potential chemical energy stored in acetyl CoA is released step by step.

In the cycle, a series of oxidations and reductions transfer that potential energy in the form of electrons to electron carrier coenzymes (mostly NAD+). The pyruvic acid derivatives are oxidized and the coenzymes are produced. Kreb’s cycle is for lipid catabolism. Glycerol is converted into dihydroxyacetone phosphate (DHAP) and catabolized via glycolysis and the Kreb’s cycle. Fatty acids undergo beta-oxidation, in which carbon fragments are spit off two at a time to form acetyl CoA which is catabolized by Kreb’s cycle.

What is glycolysis? **Glycolysis creates to ATP molecules The main pathway for oxidation of glucose to pyruvic acid: Glycolysis is usually the first stage in carbohydrate catabolism. This occurs from the oxidation of glucose to pyruvic acid. Most microorganisms use this pathway and it occurs in most living cells. The term “glycolysis” means the splitting of sugar. The sugars are oxidized, release energy and then their atoms are rearranged to form 2 molecules of pyruvic acid. **Glycolysis does not require oxygen!

Explanation of cellular respiration: Cellular respiration takes place after the glucose is broken down in pyruvic acid which is then channeled into the next step of either fermentation or cellular respiration. Cellular respiration is defined as the ATP-generating process in which most molecules are oxidized and the final electron acceptor is (almost always) an inorganic molecule. **operates via an electron transport chain * Aerobic respiration the final electron acceptor is O2 Anaerobic respiration the final electron acceptor is an inorganic molecule other than O2 What is an electron transport chain and why is it important? It is a system in which electrons pass through a series of different electron carriers to molecules or oxygen or other oxidized inorganic and organic molecules. The process occurs in the plasma membrane of the prokaryotes and in the mitochondrial membrane of eukaryotes. What is microbial growth? It is the growth in numbers of populations or an increase in the number of cells

What are three physical requirements of microbial growth? PH, temperature and moisture Define psychotrophs: Are cold loving microbes, will usually be found growing in the refrigerator such as listeria (20-25oC) How does PH affect growth? Certain bacteria thrive in a specific PH environment. Acidophiles like a PH of 5. 4 or below whereas Neutrophiles (most human pathogens) prefer a more neutral environment (5. 5-7. 5 PH) Define halophiles: Extreme halophiles (obligate halophiles) are microbes that require a high salt concentration that is required for growth.

Faccultative halophiles (most common) are microbes that do not require high salt concentrations for growth but can tolerate high salt solutions. How does osmotic pressure effect microbial growth? Microorganisms obtain most of all their nutrients in solutions surrounding water; therefore water is required for growth. They are composed of 80-90% water. High osmotic pressures have the effect of removing vital water from a cell. If a microbe is in a solution in which the concentration of solutes is higher than in the cell, the microbe is in a hypertonic environment which will create pressure on the cell.

It will crush the cell causing the cells water to push out through the plasma membrane into the high solute concentration. What are some chemical requirements for microbes? Carbon- one of the most important for microbes next to water because it is the structural backbone Nitrogen- it is required for protein synthesis (requires some sulfur), also needed for DNA or RNA synthesis (needs some phosphorous) Vitamins and minerals- needed for essential function of enzymes, usually as co-factors. What are some organic growth factors?

Essential organic compounds an organism is unable to synthesize are known as organic growth factors. They must be directly obtained by the environment. One group of organic growth factors is vitamins for human. What is a media? A media is a nutrient prepared for the growth of microorganisms. In the lab we use nutrient broths and nutrient agars. What are canophiles? Canophiles (aerobic bacteria) are microbes that grow better at high CO2 concentrations. Low oxygen high CO2 conditions resemble those found in the intestinal tract, digestive tract and other body tissues where pathogens grow.

Why is a selective media desireable? Because a selective media will suppress the growth of unwanted bacteria while encouraging the growth of the desired microbes. How do prokaryotes reproduce? Reproduce by binary fission (most common) while others may go through a “budding” process 2 Categories used to control microbes (physical and chemical) Physical: Heat (dry heat such as flame or in hot ovens) heat will denature the protein causing the proteins shape to change making it no longer usable by the organism.

Or (moist heat) such as with an autoclave which will force steam inside of the organism very quickly and cause it to break down Chemical: surfactants such as soaps which will work as a binding agen to the microorganism causing it to break off and be rinsed off or phenols which will disrupt the cell membrane or denature the protein therefore disrupting protein synthesis What are physical methods to control microbes? * Heat (dry and moist heat) * Cold * Radiation * Membrane filtration * Drying * Osmotic pressure What are the most common and effective ways of controlling microbes?

An autoclave machine that utilizes heat, steam and pressure to kill microbes and their endospores in about 15 minutes (prions are not killed) Is it more effective to control or kill microbes? It is more effective to control the microbes because we can study live bacteria, but not if they are dead Why would we want to control microbial growth? Controlling microbes can prevent infections and food spoilage Compare and contrast chromosomes in prokaryotes and eukaryotes: Prokaryotes have 1 chromosome (only one allele)

Eukaryotes have 2 chromosomes (2 alleles) DNA is not always the genetic material. What are the exceptions? How could mutations give rise to new alleles of a gene? How does translation differ from transcription? Transcription in the synthesis of a complementary strand of RNA from a DNA template Translation is the protein synthesis that involves decoding of nucleic acid and converting the information into the language of the proteins What are the differences between the leading and lagging strand?

Leading strand gets replicated sequentially and gets filled first. The lagging is the strand that gets replicated sporadically based off of what is left. What are three types of RNA and what do they do? Messenger RNA (mRNA): carries genetic information from the nucleus to the cytoplasm. Transfer RNA (tRNA): transfers the necessary sequence by carrying the code. Ribosomal RNA (rRNA): helps in synthesis of proteins. Explain mutations: A mutation is the change in the base sequence of DNA. Some mutations are bad such as when the gene for an enzyme mutates.

The enzyme encoded by the gene may become inactive or less active because its amino acid sequence has changed. But a mutation can also be beneficial such as when an altered enzyme encoded by the mutant gene suddenly has new or enhanced activity that will benefit the cell. List and discuss common mutagens: Define genetic engineering: Manufacturing and manipulating genetic material in vitro also called recombinant DNA (rDNA ) What is recombinant DNA? A DNA molecule produced by combining DNA from two different sources. Exchange of genes between two DNA molecules) **Contributes to a populations genetic diversity (source of variation in evolution) What are three processes involved in making recombinant DNA? Transformation in Bacteria Conjugation in bacteria Transduction in bacteria What is a restriction enzyme? An enzyme that cuts double stranded DNA at specific sites between nucleotides Pg. 249 What is conjugation? The transfer of genetic material from one to another involving cell to cell contact What is a plasmid? A small circular DNA molecule that replicates independently of the chromosome

Free Essays

Biology in Everyday Life

Biology Ariticle Summary #2 How Darwin won the evolution race Stem cells are defined by their ability to self-renew or to differentiate into a range of somatic cell types. Adult stem cells, such as hematopoietic stem cells are found in specialized niches within the body and have been studied for decades. Much of our knowledge about these cells is based on in vitro experiments but the effects of moving them from their in vivo niche to culture conditions are unclear. This Perspective from Penney Gilbert and colleagues from the USA and Sweden focuses on adult stem cells found in skeletal muscle, also known as satellite cells.

They address the problem that, once extracted from muscle and placed into culture, satellite cells quickly lose their ability to self-renew, complicating studies into their biology. The development of new bioengineering approaches, such as hydrogel microwell arrays, could solve this problem. These approaches can accurately monitor the behavior of satellite cells and provide robust data sets, thanks to the number of different tests that can be carried out in parallel. To illustrate the usefulness of such tools, the authors show how stem cell division and self-renewal can be tracked in clonal assays using time-lapse microscopy.

By increasing the stiffness of the hydrogel microwells in the assays, satellite cells can be maintained in culture for up to one week and successfully engraft back into mouse muscle. Stem cells hold the potential to become part of powerful medical treatments and therapies, but only if we understand how we are changing them by removing them from their niche. This Perspective pushes this issue to the fore and offers some suggestions as to how we can further improve stem cell culture http://the-scientist. com/2012/04/01/are-cancer-stem-cells-ready-for-prime-time/

Free Essays

Biology Osmosis Observation

Biology laboratory work: Osmosis observation Measuring the dependence of net mass gain in potato pieces on concentration of sugar solution By Jonas Kulikauskas Siauliai Didzdvaris Gymnasium Hypothesis: The more sugar in solution, the more potato mass will decrease. Aim: To see how potato mass will change at different concentration solution. Research question: How the mass of potato will change at different concentration solutions? Variables: Dependent: solution concentration.

Independent: sugar concentration in potatoes. Controlled: time, potato form. Apparatus: 1. 5 plastic cups 2. Distilated water 3. Potato 4. Knife 5. Clock 6. Electronical scales (±0,05) 7. Bag of sugar 8. Measuring cylinder 9. Tap water Method: Peeling down the potato and cutting it into 1cm3 cubes (25 cubes) Weighing potatoes on the scales Putting different amount of sugar into five plastic cups (1st no sugar 2nd 6,8g 3rd 13,7g 4th 20,5 5th 27,4g) Adding 100ml of water to each of the cups Mixing the sugar with water

Putting in 5 potatoes into each cup Waiting 20 minutes Pulling out the potatoes, drying them up and putting on the scales Writing down new mass. Amount of sugar in solutionSolution concentration %Cup numberMass of five cubes before(±0,05g)Mass of five cubes after (±0,05g) 0g0%15,8g6g 6,8g6,37%25,1g5,2g 13,7g12,05%35,5g5,3g 20,5g17. 01%45,6g5,4g 27,4g21,51%55,5g5,3g Graph: While the concentration is from 0% to 6,37% the net mass gets bigger, later on from 12,05% to 21,51% the net mass gets smaller.

When the concentration is from 0% to 6,37% the net mass change is positive, when from 17. 01% to 21,51% – negative. Conclusion: The potato lost more mass as it was submerged in bigger concentration solutions because the bigger concentration difference is, the osmosis will occurs more intensively. Evaluation: I think that laboratory work went pretty well, I managed to see the differences in potato mass change and make a conclusion of it. Next time I should write down original numbers and not rounded ones to give more accurate results.

Free Essays

Biology Lab

Lab  #1  ? Introduction  to  the  Microscopy  & Observation  of  Prokaryotic  and  Eukaryotic Cells Introduction Many  of  the  cells  and  organisms  that  you  will  be  studying  are  at  the  lower  limits  of  visibility  of  light  microscopes;  therefore,  it  is  extremely  important  that  you  attain  critical  lighting  and  focussing. It  is  also  important  to  handle  the  microscope  competently  to  avoid  damaging  either  the  microscope  or  the  preparation  you  are  studying. Even  students  who  have  previously  used  microscopes should read the instructions carefully. Guide Biolabo Using a web rowser, go to  the  following  web  site: http://salinella. bio. uottawa. ca/biolabo/  (you  can  try  it  from  home). Under  Microscopy  you  will  find  links  to  pages  that  describe  both  type  of  microscopes  you  will  use  this  semester,  as  well  as  how  to  set  up  and  use  them. It  is  strongly  recommended  that  you  visit  these  pages  prior  to  attending your first lab. Image J / Qcapture Although  you  can  make  all  your  observations  by  watching  directly  through  the  oculars,  it  also  can  be  done  on  the  computer  screen  using  the  digital  camera  attached  to  each  microscope.

For  that,  you  will  use  the  Image  J  program  together  with  a  capture  plugin called  Qcapture. Visit  the  lab  website  to  learn  how  to  use  Image  J  (link  on  the  homepage). All  observations  can  be  made  on  your computer  screen  or  in  the  oculars. Each  method  has  its  advantages  and  drawbacks;  you  will  have  to  choose  which  one it more appropriate (or the one you prefer): Oculars Screen ? Greater resolution ? Wider field of view ? Can share observation with others ? More comfortable for users ? Take pictures while observing Lab1 ? Microscopy The Compound Microscope On  the  Guide  Biolabo  page  click  on  the  CX41  Compound  Microscope  link  then  on  Parts  and  Function. This  will  bring  up  a  labelled  line  diagram  of  your  microscope. Familiarize  yourself  with  the  various  components  shown  in  this  figure. Then,  click  on  Setup  and  Bright  field  alignment  in  order  to  know how to use and handle the microscope. Now,  locate  your  compound  microscope  in  the  cupboard  below  the  sink  of  your  workstation. Place  it  on  the  counter  between  the omputer  and  the  end of the counter. Be sure that whenever you transport the microscope, it  is  always  kept  upright;  the  ocular  lens  will  fall  out  if  the  scope  is  tilted  or  swung. Even  though  you  don’t  need  the  dissecting  microscope  right  now,  take  it  out of the cupboard and install it beside the compound microscope. Connect  one  firewire  cable  to  each  of  the  cameras  installed  on  top  of  the  microscopes. This way, everything is setup for further observations both on  your computer screen and through the oculars. Parts of the compound microscope

The  microscope  consists  of  a  system  of  lenses,  a  light  source,  and  a  geared  mechanism  for  adjusting  the  distance  between  the  lens  system  and  object  being  observed. There  are  a  number  of  important  components  and  it  is  essential  that  you  be  able  to  identify  them  and  understand  their  function  before you can proceed. By going through the different modules in Biolabo  and  using  the  microscope  you  will  develop  a  competency  for  bright  field  microscopy. Identify  the  following  components  using  Biolabo  (Parts  and  functions  figure) and your microscope:

REVOLVING NOSEPIECE: Supports the various objectives ? You will only use  the 4x, 10x and 40x objectives in the BIO1140 labs (not the 100x). STAGE:  Supports  the  specimen  being  observed. A  system  of  knobs  on  the  side  of  the  stage  allows  you  to  move  the  specimen  under  the  objective  on  the X and Y axes. Try and move the stage. COARSE  FOCUS  KNOB:  Permits  rapid  change  in  distance  between  the  specimen  and  the  objective  thereby  allowing  for  rough  focussing  –  Do  not  use when focusing with the 40x objective

FINE  FOCUS  KNOB:  Permits  small  changes  in  distance  between  the  specimen  and  the  objective  and  thereby  allows  for  final  focussing  of  the  image. 10 Lab1 ? Microscopy OCULAR  OR  EYEPIECE:  A  magnifying  element  in  the  microscope,  usually  10X. It  is  through  the  ocular,  or  eyepiece  that  one  looks  at  the  specimen. All  our  microscopes  are  parfocal,  so  that  when  an  object  is  in  focus  with  one  objective,  the  focus  will  not  be  completely  lost  when  changing  to  the  next objective. OBJECTIVES: The magnifying element which is closest to the specimen.

See  figure 1 to find out about the engravings on the side of each objective. CONDENSER:  System  of  lenses  that  concentrates  the  light  furnished  by  the  illuminator. It does not magnify the object. CONDENSER  HEIGHT  ADJUSTMENT  KNOB:  Allows  one  to  focus  the  concentrated light onto the specimen. APERTURE IRIS DIAPHRAGM: Used to reduce glare from unwanted light by  adjusting the angle of the cone of light that comes from the condenser; Production of Image by a Compound Microscope The  most  important  part  of  a  microscope  is  the  objective.

All  the  other  parts of the instrument are designed to help the objective produce the best  possible image. The best image is not the largest; it is the clearest. There is  no  value  to  a  high  magnification. If  the  resolution  is  poor  you  will  have  no  better understanding of the specimen. light beam ocular lens Magnification Numerical aperture (NA) Determines  the  resolving power of the objective* Optical  tube  length  /  max. coverslip thickness in mm prism objective lens specimen condenser lens Figure 1: Objectives engravings light source

Figure 2: Image production in a compound microscope. 11 Lab1 ? Microscopy *Resolving power is the ability to see two objects that are very close as two  separate objects. The human eye will resolving power is about 100µm. Using the compound microscope Always  handle  the  microscope  GENTLY! It  is  an  expensive,  delicate  and  heavy  instrument. Carry  it  with  two  hands,  one  hand  on  the  arm,  and  the  other  hand  under  the  base. If  the  ocular  or  objective  is  dirty,  wipe  it  clean  using  ONLY  Kimwipes  or  special  lens  tissue  and  cleaning  fluid  supplied.

If  you  use  anything  else  you  may  scratch  the  lens. Wipe  up  any  cleaning  fluid  immediately;  otherwise  it  will  dissolve  the  glue  which  holds  the  lens  in  place. REMEMBER, your demonstrator is here to help, so… ASK! 1. Make  sure  that  the  power  cord  is  plugged  into  the  back  of  your  microscope and into a power outlet. 2. Using the letter “e” microscope slide provided, follow steps 2 through 13  in  the  Setup  and  Bright  field  alignment  procedure  of  Biolabo. Remember,  observation can be done on screen or through the oculars. Orientation and working distance . Starting  your  examination  with  the  4X  objective,  position  the  letter  “e”  slide on the stage. 2. Draw what you see in the microscope:_________________ 3. What would a slide with the letter “t” look like under the microscope? _________________ 4. Using the knobs located on the side of the stage and looking through the  microscope,  move  the  slide  slowly  to  the  right,  then  to  the  left. Record  your observations. ___________________________________  5. Now,  move  the  slide  slowly  away  from  you,  then  towards  you  while  observing through the microscope.

Record your observations  ____________________________________ 6. Focus on the slide at 10X. Check the distance between the objective lens  and your slide (= the working distance, see also the reference at the end of  this  chapter). Now  switch  to  the  40X  objective  and  check  the  working  distance. What  happens  to  the  working  distance  as  your  magnification  increases? 12 Lab1 ? Microscopy Depth of field (depth of focus) Lenses  have  a  depth  of  focus. It  is  the  number  of  planes  in  which  an  object  appears  to  be  in  focus.

Extend  your  fist  at  arm’s  length  in  front  of  you  and  hold  your  thumb  up. Concentrate  on  your  thumb  and  notice  that  the  objects past your thumb on the other side of the room are not clearly seen. Similarly  with  a  microscope,  when  it  is  focussed  on  one  surface,  the  surfaces lower or higher will be out of focus. 1. Position  a  prepared  slide  with  coloured  threads  upon  the  stage. At  low  power, 4X, focus on the area where the threads cross. 2. Using the fine focus adjustment, focus up and down slowly. 3. Repeat  using  different  objectives.

What  can  you  say  about  the  depth  of  field  at  different  magnifications? Has  it  increased  or  decreased? (i. e. ,  can  you see more threads in one focal plane at 4X or 40X? ) ____________________________________________________________ Magnification The magnification given by objectives and oculars is engraved on them. The  total  magnification  for  any  combination  of  objective  and  ocular  is  the  product of the magnification of each lens. Objective magnification Ocular magnification Total Magnification Light intensity Working distance 4x 10x 40x High 22mm 10x 10x 100x

Medium 10. 5mm 40x 10x 400x Low 0. 56mm Table1  . Comparison  magnification,  working  distance  and  brightness  at  three  different  objective magnifications. You also can calculate the magnification of your picture using the following  formula: Magnification factor= measured size of object = (             X) Actual size of object 13 Lab1 ? Microscopy Specimen  size  and  Magnification  of the picture Before  you  start  this  exercise,  make  sure  you  have  carefully  read  the  website  section  relevant  to  the  software  you  will  use  to  take  digital  pictures (ImageJ/Qcapture).

The  goal  of  this  section  is  to  teach  you  different  techniques  that  will  allow  you  to  determine  the  size  of  objects  you’re  observing  under  the  microscope. The  general  principle  is  fairly  simple:  2  objects  have  the  same  relative  size  (expressed  as  a  ratio)  in  the  real  world  and  under  the  microscope. actual size of object A   = on? screen size of object A  ? A1 = A2   actual size of object B      on? screen size of object B         B1    B2 The following exercises are applications  of this formula. Place a slide under  the  microscope.

Choose  the  right  objective  and  adjust  the  focus  and  light  level. Then, choose a structure you want to measure and take a picture. A? First  method:  Measuring  an  object  using  the  field  of  view (FOV): The  simplest  way  to  determine  the  size  of  an  object  is  to  use  the  known  size of the whole field of view (FOV, the whole picture from left to right). 1? On  the  computer  screen  (using  a  ruler  and  without  writing  anything  of  the screen), measure the object of which you want to determine the size (=  A2) 2? Then, measure the width of the whole picture on the screen (=B2). ? Refer  to  table  2  on  page  20  to  know  the  actual  size  of  the  field  of  view  for the objective you’re using (=B1) 4? Use the following formula: Actual size of the object (A1) = Actual size of the FOV (B1)     x   on? screen size of the object (A2) on? screen size of the FOV (B2) Example:  On  a  snapshot  using  the  4x  objective,  an  insect  has  an  on? screen  length of 10cm. The whole picture is 20cm wide. What is the actual size of the insect? ______________________________ 14 Lab1 ? Microscopy B? Second  method:  Measuring  an  object  using  a  scale  bar file:

From  Image  J  (using  the  file  /  open  command),  open  the  file  that  contains  the  relevant  scale  bar  in  the  (T:/BIO/BIO1140):  new10X. jpg  for  the  10x  objective, and new40X. jpg (for the 4x and 40x objectives). Then,  using  a  ruler  measure  the  following  distances  directly  on  the  computer screen: 1? The  on? screen  length  (or  width)  of  the  object  whose  size  you  wish  to  determine (=A2) 2? The width of the scale bar on the screen (=B2)  You now can calculate the actual size of the object using the formula: actual size of object = on? creen length of object  x  actual size of scale bar*                                            on? screen length of scale bar ?    A1 = A2 x B1 B2 *The  actual  size  of  the  scale  bar  is  indicated  on  the  scale  bar  file  (ex:  on  the  new10x. jpg  file, the bar represents 0. 2mm at 10x or 0. 02mm at 100x) = B1 Example: I took a picture of a small insect larva, using the 4x objective. The  larva  length  is  60mm  on  the  screen. The  scale  bar  on  the  new40x. jpg  is  30mm and represents 0. 2mm. What is the actual size of the larva? _________________________

Do not put the compound microscope back in the cupboard you will need it  later this afternoon. Points to remember concerning microscopes 1. Always  work  with  a  clean  microscope. Use  only  the  lens  paper  provided. Don’t forget to clean the slide too! 2. Always  locate  the  specimen  under  low  power  and  work  your  way  up  to  the high power objective. 3. Never  use  the  coarse  focusing  knob  when  the  high  power  lens  is  in  position. Use only the fine focus knob. 4. Never use the 100x in 1st year labs (we didn’t teach you how)  5.

Always  readjust  illumination  whenever  you  change  the  objective. Too  much light will give you a blurry image that you cannot focus on. 15 Lab1 ? Microscopy The stereoscopic microscope (dissecting microscope) The  stereoscopic  microscope,  also  called  stereoscope  or  dissecting  microscope,  is  used  to  view  objects  that  are  too  large  or  too  thick  to  observe under the compound microscope. Stereo  microscopes  are  always  equipped  with  two  oculars  producing  a  stereoscopic  or  three? dimensional  image. Unlike  the  compound  microscope, the image is not inverted.

Our  stereo  microscopes  provide  magnification  in  the  range  of  6. 7X  ? 45X  using  a  zoom? type  lens  system. By  rotating  a  dial  located  on  the  right  side  of  the  stereo  microscope  head,  the  viewer  obtains  a  continuous  change  of  magnification. Our  stereo  microscopes  can  be  used  with  reflected  or  transmitted  light. Reflected  light  is  directed  unto  opaque  specimens  from  above  and  is  reflected  to  the  viewer. Transmitted  light  is  used  with  translucent  specimens  and  passes  through  the  specimen  from  beneath  the  stage  and  into the viewer’s eyes.

Use of the stereoscopic microscope 1. On  the  Biolabo  home  page  left  click  on  Stereoscope  (Dissecting  microscope) and then on Stereoscope setup. 2. Click on Step 1 and read it carefully. Obtain a stereo microscope from the  same cupboard as your compound microscope if you haven’t yet. 3. Click on and read steps 2 through 7. 4. Place a coin on the stage. 5. Using  the  focussing  knob  on  either  side  of  the  arm,  lower  or  raise  the  objective  until  the  coin  is  in  focus. Examine  it  in  both  reflected  and  transmitted light.

Which  is  best  for  an  opaque  specimen? Try  the  various  magnifications  by  turning  the  zoom  knob. The  reflected  light source  is  similar  to  a  spotlight  and its orientation can be adjusted manually. Try rotating the light upwards  and downwards. 6. Examine other materials such as brine shrimp larvae (Artemia) in a watch  glass  using  both  reflected  and  transmitted  light. Add  1? 2  drops  of  “proto? slow”  solution  to  slow  down  the  larvae. Estimate  the  actual  size  of  one  larva: __________ 16 Lab1 ? Microscopy Prokaryotic and Eukaryotic cells

It  has  long  been  recognized  that  living  organisms  are  composed  of  basic  structural  and  functional  units  called  cells. Cells  can  be  divided  into  two  general  types:  prokaryotic  and  eukaryotic,  based  on  the  presence  of  a  nucleus and other membrane bound organelles in the latter. Prokaryotic  cells  belong  to  2  big  groups:  archaea  and  eubacteria. They  are  usually  smaller  than  eukaryotic  cells  (typically  1? 5µm). These  unicellular  organisms may be small, but they are the most abundant organisms on the  planet,  representing  about  half  the  biomass  (Biology,  Brooker  et  al. 010,  McGraw? Hill&Ryerson). They  are  devoid  of  membrane  bound  organelle  such  as  the  nucleus,  mitochondria  or  chloroplasts. Their  genetic  material  is  usually  composed  of  one  circular  chromosome  plus  other  extra  chromosomal elements called plasmids. Eukaryotic  cells  are  usually  much  larger. They  possess  a  membrane  bound  nucleus,  their  organelles  are  more  complex  and  numerous,  and  their  genome  is  larger  than  prokaryotes. Eukaryotic  organisms  can  be  uni? or  multicellular. You  will  have  a  chance  to  observe  many  eukaryotic  cells  during this semester: Amoeba, Lilly, Whitefish….

In  today’s  exercise  you  will  take  a  first  look  at  the  similarities  and  differences  between  prokaryotic  and  eukaryotic  cells  as  well  as  the  diversity within these groups. You  should  familiarize  yourselves  with  a  whole  array  of  cellular  structures  and  organelles  you  will  probably  encounter  during  the  course  of  this  exercise. Before  your  scheduled  lab  session,  write  down  the  definition  and  function for each of the following terms: plasma (cell) membrane, cell wall,  protoplast, cytoplasm, vacuoles, nucleus, nucleolus and chloroplasts.

Eukaryotic Cells: Elodea (plant) 1? Get  a  young  green  Elodea  leaf  from  the  jar. Mount  it  in  a  drop  of  water  on  a  clean  microscope  slide  with  the  convex  side  of  the  leaf  uppermost. Cover the preparation with a coverslip. 2? Observe  the  preparation  at  4X,  then  at  10X. If  you  see  brownish  oval  structures  on  the  leaf  surface,  ignore  then. These  are  probably  epiphytic  diatoms. Concentrate your attention on the cells near the central rib at the  base of the leaf and on the marginal cells at the edge of the leaf. Can you distinguish several layers making up the leaf? ____ ? What  is  the  average  length  ______  and  width  ______  of  the  cells  in  micrometres? 17 Lab1 ? Microscopy 3? Focussing at 40X locate the cell wall, the vacuole, the cytoplasm and the  numerous green chloroplasts. ? What  important  biological  process  takes  place  in  the  chloroplasts? _____________________________________ ? What pigment is responsible for their green colouration? ________________________________________________ ? What is the shape of chloroplasts? ____________________________________________ ? Are the chloroplasts moving? What sort of movement? _________________________________________________ ? The phenomenon you are observing is called cytoplasmic streaming  or  cyclosis. What  do  you  think  the  function  of  such  a  process  could  be? ___________________________________________________ 4? You  have  probably  realised  that  the  plasma  membrane  cannot  be  seen  in  plant  cells. It  is  too  thin  to  be  resolved  with  the  compound  microscope.

In  order  to  see  the  true  limiting  boundary  of  the  cytoplasm  it  is  necessary  to  treat  the  cells  in  such  a  manner  that  the  plasma  membrane  becomes  withdrawn  away  from  the  rigid  cell  wall. This  can  be  done  by  placing  the  cell  in  a  strong  salt  solution. This  will  cause  water  to  diffuse  out  of  the  cell  by  osmosis,  thereby  decreasing  the  cell  volume. The  unaffected  cell  wall remains in its original state. What can then be seen is a space between the  cell wall and the limiting boundary of the protoplast (the cell minus the cell  wall) which thereby becomes visible. Remove  your  Elodea  slide  from  the  microscope  stage. Delicately  remove  the  coverslip,  add  one  drop  of  5%  NaCl  solution  then  put  back the coverslip on your preparation ? Refocus  at  40x  (don’t  forget:  you  must  first  focus  at  4X,  then  10X  and finally at 40x). ? Are  the  cells  plasmolyzed? (If  not  wait  a  while  longer). How  do  they  look like now? ______________________ ? Has the cell wall been affected? _________________  ? What  becomes  of  the  large  central  vacuole  during  plasmolysis? ______ _______________________________________________ Take a picture of a plasmolyzed Elodea cell. How does it compare to  the previous picture? 18 Lab1 ? Microscopy Prokaryotic Cells: Lyngbya (eubacteria: cyanobacteria)  1. Take  a  close  look  at  the  sample  in  the  jar. Which  colour  would  best  describe its appearance? ___________________ 2. Prepare a wet mount of fresh Lyngbya by the following procedure:  ? With  forceps  or  an  eye  dropper,  put  a  very  small  amount  of  green  matter on a clean slide ? Add a drop of water from the jar. ? Carefully  place  a  coverslip  over  it. Make  sure  it  lies  flat  on  the  preparation.

Don’t  worry  if  there  are  just  a  few  air  bubbles. With  practice,  your  skills  will  improve. However,  if  too  many  air  bubbles  are  present,  your  preparation  risks  to  dry  out  very  quickly  during  viewing, compromising your observations. 3. Starting with the 4X objective, focus on your preparation. ? Can you see numerous green filaments? _______ ? Are the filaments moving? __________ 4. Switch to the 10X then the 40X objective and focus using the fine focus  knob only: ? Do you see the individual cells making up each filament? ________ ? Estimate the width of one filament in micrometres:_______ What’s the filament width in millimetres (mm)? ________ ? REMEMBER:  You  are  working  with  living  cells. Work  quickly  and  keep  your  specimen  wet  at  all  times. Dead,  dry  or  damaged  biological preparations are useless. Returning the microscopes after use After  completing  all  observations,  turn  and  click  the  low  power  objective  (4X) on the compound microscope into position. Remove the slide from the stage and return it to its correct box. Wipe the stages with a clean paper towel. Carefully disconnect the camera from the firewire cable.

Make  sure  you  turned  off  the  light  on  each  microscope,  then  unplug  the  power cord and make a loose coil of it around the eyepieces. Return the microscope in the cupboard. 19 Lab1 ? Microscopy TAs  will  check  that  you  properly  returned  the  microscopes  in  the cupboard  with the cord properly attached and no slide present on the  stage. You  will  lose marks for this lab (and other labs) if you don’t do so. Evaluation A  short  quiz  on  microscope  components,  specimen  observations  and  measurement of objects will take place at the beginning of Lab2.

Be on time, the quiz will start at 2:30. References: 1? Metric system (see also appendix IV at the end of lab manual):  1 centimetre cm = 10? 2 metres (m) 1 millimetre mm = 10? 3 metres 1 micrometre ? m = 10? 6 metres 1 nanometre nm = 10? 9 metres 2? Size of camera field of views (fov): Table 2: Fields of View: Olympus CX41 Compound Microscope  Objective 4X 10X 40X 100X Camera field of view (width in mm) 1. 75 0. 70 0. 175 0. 070 Table 3: Fields of View – Olympus SZ61TR Dissecting Microscope  Zoom Setting 0. 67X 0. 8X 1X

Free Essays

Microbiology: Bacteria and Fresh Yogurt Slide

Bacterial Morphology Demonica Britt Microbiology DL1 March 23, 2013 Abstract This lab was performed to identify and familiarize with a microscope while precisely observing various bacterial shapes and their arrangements in different types of specimens of bacteria. The microscope parts and capabilities were clearly identified and used successfully and the bacteria were clearly illustrated showing the bacterial shapes and arrangements with all the appropriate magnification being utilized.

Through various magnifications using 10x, 40x and 100x oil immersion lenses, the bacteria specimens, along with fresh and prepared yogurt, demonstrated full visual optical views of their shapes and how the different types were displayed at different levels of magnification. Purpose The purpose of the experiment was to gain full knowledge and experience of operating a microscope while being able to successfully visualize different types of bacterial and yogurt specimen’s shapes and arrangements using several magnification techniques by way of 10x, 40x,100x oil immersion lenses and a light source.

The main purpose was to observe the shapes and arrangements of microbial bacteria and yogurt. Procedure The lab involved self-provided and labpaq materials to perform several exercises to obtain the purpose of the lab. The lab began with the proper identification of all components of the microscope and their functions. This allowed for preparation of the objective of being able to view specimens at various magnification levels and recognizing their different shapes and how they are arranged contingent upon those identified within the lab itself and the microbiology textbook.

Several different slides were observed under 10x and 40x lens magnification: Paramecium conjugation, Yeast, Amoeba Proteus, Ascaris eggs, Anabaena, and Penicillium. This allowed vivid illustrations of the specimens notating their shapes and how they are arranged. The bacteria were observed through the eyepiece at the appropriate focus, resolution, and contrast for maximum visibility. The next part of the lab exercise was observance under an 100x oil immersion lens for more prepared slides: Bacteria Coccus form, Bacteria spirillum, and Bacteria Bacillus form while still maintaining to observe the shapes and arrangements.

Additionally, the fresh yogurt slide that was sitting for 24 hours in a dark, warm location was obtained for the next part of the lab experiment. The fresh yogurt slide was prepared by using a toothpick to place a small amount onto a fresh, clean slide with a slide cover placed on top. This was observed for comparison to the prepared yogurt slide included in the lab for any variations in forms. Upon completion of performing the lab, the prepared slides were safely put away, fresh slide washed carefully, fresh yogurt specimen safely discarded, and the microscope cleaned and returned to be stored with the protective cover.

Data/Observations – (Data Tables & Photos of Labeled Pics & Observations) The bacteria slides clearly displayed the various types of bacteria shapes and showed how each follow a specified arrangement. Under the lowest magnification the object is relatively smaller and not as easy to see the full format. Whereas the higher the magnification, the bigger and more enhanced the view of the bacteria becomes making the shapes and arrangements relatively obvious. It appeared to become clearer the bigger the object projected to my eye.

It became life size in a sense where as it was an image that could be clearly defined, described and duplicated if necessary. The fresh yogurt slide that was set for 24 hours was a more enhanced feature for observing bacteria in yogurt. Its view was very detailed and its shape more recognizable. While the prepared yogurt slide was a more faint view and the color appearing duller. It was visible to me that bacteria in yogurt was more spherical in shape, cocci. Results A. What are the advantages of using bleach as a disinfectant? The disadvantages? The advantages of using 70% alcohol?

The disadvantages? Bleach is a common household disinfectant that kills 99. 9 percent of germs whereas others cannot approach this effectiveness. It can be used to sanitize. It can be a disadvantage as it can be inactivated by presence of an organic matter and it has a strong odor and it has a short life in the liquid form that can be sensitive to heat and sunlight. The advantages of using 70% bleach is that it can be capable of killing most bacteria which is safe for skin contact and it prevents dehydration and the alcohol part of it affect the cells in various ways.

Some disadvantages are that they are hazardous which contain compounds that are not safe and toxic to human form. B. List three reasons why you might choose to stain a particular slide rather than view it as a wet mount. C. Define the following terms: Chromophore: Acidic Dye: Basic Dye: D. What is the difference between direct and indirect staining? E. What is heat fixing? F. Why is it necessary to ensure that your specimens are completely air dried prior to heat fixing? G.

Describe what you observed in your plaque smear wet mount, direct stained slide, and indirectly stained slide. What were the similarities? What were the differences? H. Describe what you observed in your cheek smear wet mount, direct stained slide, and indirectly stained slide. What were the similarities? What were the differences? I. Describe what you observed in your yeast wet mount, direct stained slide, and indirectly stained slide. What were the similarities? What were the differences? J. Were the cell types the same in all three specimen sets:  yeast, laque, and cheek? How were they similar? How were they different? Conclusion/Discussion Upon performing and completing the experiment I learned that the microscope is a very delicate tool that allows the capability of viewing specimens too small for the human eye. With adjusting the focus, contrast, and resolution, the bacteria become more visible to the eye. On top of that, viewing the specifications at different magnifications the bacteria shapes and arrangements become more present within the specimen.

Bacteria comes in different forms and shapes and just by arrangement alone, they can be classified morphologically. It was also visual that there are differences in a fresh slide containing bacteria compared with a slide already prepared. I did not expect to see the differences so vividly displayed, but after using the microscope it was determined that anything not visible to the naked eye still has the capability to be seen and the microscope is the perfect tool to use to be able to do so.

Free Essays

10th Grade Biology Textbook Analysis

10th Grade Biology Textbook Analysis: A Readability Study Teachers should consider assessing the textbooks they are planning to use in the classroom. Textbook evaluations and assessing students’ connections with texts are important tasks for content area teachers and students (Vacca, 2002). Teachers are constantly assessing the suitability of reading material for their students. Readability can be defined as the grade level at which a document is written. Readability is concerned with the factors that affect students’ success in reading and understanding a text.

These factors include the legibility of the print and illustrations, the motivation and interest of the reader, and the reading level of the text in relation to the reading ability of the reader (Johnson, 1998). These key ideas of readability are at the heart of choosing the best textbooks for students. There are many readability formulas or indexes teachers can use to objectively measure the readability of textbooks. Many readability formulas have been developed as a result of research evidence (Johnson, 1998).

Most readability formula and index values are calculated by measuring sentence length and word familiarity or word length to determine a grade-level score for text passages (Vacca, 2002). There are several widely used readability formulas. The Fry Readability Graph was developed by Edward Fry in 1977 for the purpose of predicting readability. It is a quick and simple readability formula. He used the common formula variables of syllables per 100 words and words per sentence.

The user marks the counts of the variables on a graph and then reads the readability grade score directly from it. The graph was designed to identify the grade-level score for materials from grade 1 though college and can predict the difficulty of the material within one grade level (Vacca, 2002). Flesch-Kincaid Formula was developed to be used as a US Government Department of Defense standard test. The formula uses two factors: the average number of syllables per 100 words and the average number of words per sentence.

The score in this case indicates a grade level (Johnson, 1998). Flesch-Kincaid Grade Level Index is automatically calculated on Microsoft® Word documents. Microsoft® Word will display readability statistics after it has completed a grammar check, which is accessible from the tool bar (Arnold, n. d. ). Dale-Chall Readability Formula has a 3,000 “familiar word” list which is used as a guide to identify “difficult words”. This formula uses two factors: the average sentence length and the percentage of unfamiliar, or difficult, words (Intervention, n. . ). Gunning’s ‘FOG’ Readability Formula is suitable for secondary and older primary age groups. Gunning proposed counting words of three or more syllables, assigning them as “hard words”. The formula is based on two counts, that of average sentence length and the percentage of “hard words” (Johnson, 1998). The ‘SMOG’ Formula tends to give higher values than the other formulas because it was intended to predict the level necessary for 90 – 100% comprehension of the reading material, i. e. when the SMOG formula yields a readability score of ten for a particular textbook, the students reading on a tenth grade level will be reading the material with 90 to 100% accuracy (Johnson, 1998). FORCAST Formula was devised for assessing US army technical manuals and is not suitable for primary age materials. But, because it is one of the only formulas that does not need whole sentences, it is suitable for assessing notes and test questions. The only factor used to calculate the FORCAST formula is the number of single-syllable words found in a sample of 150 total words (Johnson, 1998).

According to Vacca (2002), the Close Procedure does not use a formula to determine readability. This procedure determines how well students can read a particular reading passage as a result of their interaction with the reading material. In this method every nth word is deleted from the passage, leaving a blank in its space. The passage is given to students to fill in the missing words and the completed passage is used to evaluate students’ ability to accurately supply the missing words.

The General Textbook Readability Checklist is a checklist that focuses on the understandability, usability, and interestability of a textbook. This purpose of this study was to examine textbook readability by applying several readability formulas, including the Fry Readability Graph, Flesch-Kincaid Formula, Flesch-Kincaid Grade Level Index, Dale-Chall Readability Formula, Gunning ‘FOG’ Readability Formula, McLaughlin ‘SMOG’ Formula, FORCAST Formula, Cloze Procedure and the General Textbook Readability Checklist, to a biology textbook titled, Modern Biology.

Method Materials Materials used in this study included a 10th grade biology textbook, Modern Biology as well as the procedural guidelines for each of the readability formulas that will be used to assess the textbook. Procedure 18 passages were randomly selected from the Modern Biology textbook and the appropriate pages photocopied.

The photocopied passages were then placed into 5 groups having three samples each (Fry Readability Graph Group- Appendix A, Flesch-Kincaid Formula Group- Appendix B, Dale-Chall Readability Formula Group –Appendix D, Gunning ‘FOG’ Readability Formula Group- Appendix E, and FORCAST Formula Group- Appendix G), and three separate groups containing one passage each (Flesch-Kincaid Grade Level Index Group- Appendix C, McLaughlin ‘SMOG’ Formula Group- Appendix F, and Cloze Procedure Group- Appendix H). A more subjective measure was used in the General Textbook Readability Checklist (Appendix I).

Procedures were followed for each of the Formulas and Indexes, and results were tabulated and reported. A brief summary and discussion were included in the write-up. Results and Discussion This purpose of this study was to examine textbook readability by applying several readability formulas, including the Fry Readability Graph, Flesch-Kincaid Formula, Flesch-Kincaid Grade Level Index, Dale-Chall Readability Formula, Gunning ‘FOG’ Readability Formula, McLaughlin ‘SMOG’ Formula, FORCAST Formula, Cloze Procedure and the General Textbook Readability Checklist, to a biology textbook titled, Modern Biology.

As table 2 illustrates, the Flesch-Kincaid Formula (10. 8 grade, 15. 8 years old) was the only readability method that supported the teacher’s decision to use this textbook. The Fry Readability Graph (Table 1) indicated that the textbook was at an 8th grade level (13 years old). The remaining objective methods for readability, Flesch-Kincaid Grade Level Index refer to Table 3 (12 grade), Dale-Chall Readability Index (Table 4 -16 grade), Gunning ‘FOG’ Readability refer to Table 5 (13. 6 grade, 18. 6 years old), McLaughlin ‘SMOG’ Formula see Table 6 (13. 1 grade, 18. 1 years old), and the FORCAST Formula see Table 7 (12. grade, 17. 1 years old) indicated that the textbook reading would be too difficult for a 10th grader. In an attempt to produce a more cohesive point on the scale of readability, the averages of six tests (Fry Readability Graph, Flesch-Kincaid Formula, Dale-Chall Readability Index, Gunning ‘FOG’ Readabilty, McLaughlin ‘SMOG’ Formula, and the FORCAST Formula) were found for the textbook. As illustrated in Table 10, the average grade for this text is found to be at the 12th grade. The Close Readability Procedure results also indicate that the reading level is to difficult for the 10th grade class (Table 8).

According to the General Textbook Readability Checklist the textbook is strongest in its usability and weakest in its understandability (Table 9). I really am not surprised that the results indicate that the textbook is too difficult for the 10th grade student. Science textbooks are probably inherently more difficult to read because the subject matter is more complex as is the terminology. Although these tests didn’t provide the desired results, there is a lot of similarities between them and I believe that they are still good measures of the readability of textbooks.

Free Essays

Ccea as Biology Coursework: an Investigation to Measure

An investigation to measure the percentage light transmission, using a colorimeter, through a solution, from pH 2 – pH 9, in which jelly cubes were immersed over a 24 hour period Interpretation Written Communication of the Data C1 Pepsin is an enzyme that works in the stomach and has an optimal pH between pH 1 and 4 or in acidic conditions. From our graph it can be seen that that the lowest mean percentage light transmission for pepsin is when the buffer has a pH of 2. Trypsin is an enzyme that works in the small intestine and has an optimum pH between pH 7 and 8 or in neutral conditions.

From our graph it can be seen that the lowest mean percentage light transmission for trypsin is when the buffer has a pH of 8. C2 and C3 As the pH of the pepsin buffer increases from pH 2 to pH 9 so too does the percentage light transmission through the buffer solution after a 24 hour period. Although when the trypsin buffer has a pH between pH 2 and 8 the percentage light transmission through the buffer solution after a 24 hour period decreases, but from pH 8 to pH 9 the percentage light transmission through the buffer solution after a 24 hour period increases. At a low pH (pH 2) the amount of gelatine broken down by the pepsin is high.

We can tell this as this is when there is a low mean percentage light transmission (16. 86%) because a lot of colour of the jelly will leak in the solution causing the colour to be deeper. But at a higher pH (pH 9) the amount of gelatine broken down by the pepsin is low. We can tell this as this as there is a low mean percentage light transmission is high (34. 14%) because a little colour of the jelly will leak in the solution causing the colour to be lighter. At a low pH (pH 2) the amount of gelatine broken down by the trypsin is low so this means there is a high mean percentage light transmission (41. 5%) because a little colour of the jelly will leak in the solution causing the colour to be lighter. At a high pH (pH9) the amount of gelatine broken down by the trypsin is high so this means that there is a low mean percentage light transmission (29%) because a lot of colour of the jelly will leak in the solution causing the colour to be deeper. C4 and C5 An enzyme is a biological catalyst which speeds up a chemical reaction without itself undergoing a permanent change. Most enzymes are globular proteins and contain active sites. The active site is the part of the enzyme which combines with the substrate.

Enzymes are specific which means that one enzyme will work on one substrate. All enzymes work best at a particular pH, their optimum pH. The proteins structure of the enzyme is altered in a more alkaline or acidic solution than the specific optimum pH. When an enzyme structure is altered it cannot fit successfully with the substrate. Activity is therefore limited to a few enzyme molecules that are still unaltered or may totally stop. The protein digesting enzymes, pepsin and trypsin, will hydrolyse the substrate, gelatine. This substrate is a major component of jelly.

When a coloured jelly, such as raspberry, is exposed to a protein digesting enzyme, the colour is released into the solution as the gelatine is broken down. The intensity of the colouring released into the buffer can be estimated with a colorimeter. Trypsin is often found naturally in neutral or slightly alkaline conditions. Therefore the most enzyme activity and most colour is released from the jelly would be expected at a pH 7 or 8 and in solutions above or below this pH there would be less colour released. Pepsin is often found naturally in very acidic conditions.

Therefore the most enzyme activity and most colour is released from the jelly would be expected at a pH 1 or 2 and in solutions above or below this pH there would be less colour released. Evaluation D1 I consider my results to be appropriate in meeting the aims of the investigation because we used a colorimeter. This measures the percentage light transmission as a numerical value. It is more appropriate than measuring the light intensity by eye as some of the results looked extremely similar and it could be hard to distinguish between samples.

It is also more appropriate than measuring the percentage change in mass of the jelly cube before and after the 24 hour period as it is difficult to extract what is left of the jelly and it is not as accurate. D2 In order to try to obtain accurate results a number of procedures had to be carried out; • Firstly, we used the same specimen of jelly. Although the jelly is from the same company there could be a difference in the composition of gelatine. If this was allowed to happen it could mean that it would take longer to break down some samples than others.

This would then affect the overall results of the experiment as it would create an anomaly. • Secondly, we also used a colorimeter which is extremely accurate when it comes to measuring the percentage light transmission. As it measures the percentage light transmission as a numerical value. • Thirdly, we only handled the side of the cuvette as if we touched the front where the light passed through it would affect how much light passed through as it will leave a finger print on the glass and make it harder for the light to pass through. • Fourthly, we kept the temperature at a constant 25°C using a water bath.

At low temperatures, an increase in temperature causes an exponential increase in enzyme activity. This is because an increase in temperature provides more kinetic energy for the collisions of enzymes and substrates, so the formation of enzyme-substrate complexes increases. At high temperatures (above 40°C), an increase in temperature causes a sharp decline in enzyme activity. This is because the bonds holding the tertiary structure of the enzyme are broken and so the active site is denatured. • We tried to use the same amount of jelly as this could affect the substrate concentration.

If the surface area of the substrate increases it means that it has an increased substrate concentration. As the substrate concentration increases so too does the enzyme activity. This is because a greater concentration of substrate increases the chances of collisions and the formation of enzyme substrate complexes. D3 Although the experiment was as fair as it could have been, there were some factors that were beyond our control; • Firstly, we could not accurately cut the cubes into equal sizes as we did not have the equipment to make a straight incision.

This would increase the surface area of the substrate which will increase the substrate concentration. This would increase the enzyme activity as it will increase the chance of collision between the enzyme and substrate and more enzyme substrate complexes can be formed. • Secondly, we could not check the temperature of the water bath on a regular basis as the experiment was carried out over a 24 hour period. If the temperature had went above 25°C it would increase the rate of reaction as it provides more kinetic energy for the collision of the enzyme and the substrate, so the rate at which enzyme-substrate complexes form is increased.

Although, if the temperature decreased below 25°C it would have the opposite effect. It would slow the rate of reaction as it will provide less kinetic energy for the collision of enzymes and the substrate, so the rate at which enzyme-substrate complexes form is decreased. D4 and D5 My experiment is reliable as it was repeated six times in the form of the pooled class result and all of the results seemed to follow the same general trend. Although, if we had more time we may have been able to do the experiment again which would make the average or mean more accurate.

However, there were a few anomalies among the group results. As you can see from table 1, in the test for trypsin at pH 9, group 2’s result decreased from the previous result (pH 8) whereas every other group increased except for group 3 who’s stayed the same as the previous result (pH 8). This could be caused from a fingerprint being put on the cuvette where the light passes through; this could lower the percentage light transmission through the solution as it will cover the glass.

Free Essays

Biology 1202 Notes

Thursday January 17 Mastering biology course id=MBPOLLACK01639 Life first appeared on earth about 4 billion years ago Origin of life is a hypothesis not a theory Very little oxygen in early earths atmosphere Spontaneous generation of life- random formation of life Millions of species on earth, up to 100 million the expirement of miller and urey showed what?

test question a few centuries ago: eople thought that new living things appeared all of the time(spontaneous generation of life) ex: mold growing on food in the mid 1800s Louis Pasteur refuted the theory of spontaneous generation of life he basically left something out but sealed it off and nothing grew on it, then he left it out without being sealed and stuff grew the cell theory- all existing cells come from pre-existing cells about 50 trillion cells make up the human body but all came from the single diploid cell formed from conception conditions on early earth: tmosphere- similar to Jupiter today, no free oxygen, frequent storms with lots of lightning, volcano eruptions, meteor impacts, UV light from the sun, no ozone layer earth before life arose:

about 4. 6 billion years old, known because of radiometric dating of meteorites and moon rocks life arose about 3. 8 billion years ago, known because of chemical traces in the rocks, fossilized bacteria was found in rocks 3. 5 billion years ago no spontaneous generation now but must have happened then how to assemble a living thing: accumulation of organic molecules atalyze reactions reproduce from stored genetic info separate the living thing from the outside environment 3 domains of life- bacteria, archaea, eukarya proteins are needed to synthesize more DNA DNA is used to synthesize RNA which is used to make protein…DNA-RNA-Protein Ribozymes: RNA molecule that can catalyze reactions, especially those involved in synthesis and processing of RNA itself Conclusion- earliest cells used RNA to store info Ribozymes used to catalyze reactions Thursday January 24th Our species has been here for about 200,000 years PRINCIPLES OF EVOLUTION

Theory- general explanation of natural phenomena, developed through extensive and reproducible observations Hypothesis- tentative explanation of observations, educated guess The origin of species was a book published in 1859 by Charles Darwin Main points of book: Evolution occurs in populations, not individuals Natural selection is the mechanism Observation 1-living things tend to reproduce as quickly as possible. Observation 2-constant population size over time (carrying capacity) Inference- competition for survival; differential reproductive success “I don’t like dogs.

They all smell like dogs and poop on my lawn” variability in structures and behaviors all of this leads to natural selection, organisms best suited to an environment leave the most offspring evolution- the genetic makeup of a population changes over time, driven by natural selection evolution- a change in the allele frequency of a population over time study pakicetus slide 1/29/13 homologous structures suggest common ancestry some homologous structures look different today because of divergent evolution 300 million years ago is when we started to see the type of mammalian limbs similar to the structure today analogous tructures=convergent evolution analogous structure do NOT suggest common ancestry similar environmental forces select for similar structures in unrelated organisms vestigial structures- rudimentary form of and organ more fully formed in ancestor “evolutionary baggage” vestigial structures are a type of homologous structure


Developmental biology- the biology of studying organisms from the unicellular stage onward WATCH DARWIN VIDEO All living things have DNA and transcribe it into RNA using amino acids Artificial selection- insecticides, antibiotics etc. Know 3 types of natural selection 1. irectional selection 2. stabilizing selection 3. disruptive selection 1/31/13 evolution of populations GregorMendel- monk who did pea expirements and shed light on the rules of inheritance He worked at the same time as Darwin but his work was overlooked until the 20th century The modern synthesis(early 1940s) – a conceptual synthesis of Darwinian evolution, mendelian inheritance, and modern population genetics Evolution- a change in phenotypic constitution of a population owing to a situation on heritable variation among pheneotypes that changes the genotypic constitution of the population Phenotype- all expressed traits of an organism

Genotype- the entire genetic makeup of an individual Evolution-a change in allele frequency in a population(change in the gene pool) Population genetics-examines the frequency, distribution, and inheritance of alleles within a population Hardy-weinberg equilibrium- the pop genetics theorem that states that the frequencies of alleles and enotypes in a population will remain constant unless acted upon by non-mendelian processes Allele frequencies- under strict mendelian inheritance, allele frequencies would remain constant from on generation to the next(hardy-weinberg equilibrium) If there is no change in allele frequency there is no evolution Biological species concept- a population whose members can potentially interbreed in NATURE to produce viable reproductive offspring Reproductive barriers- isolate populations from one another

Speciation- the process by which new species form EXAM 1 Two requirement for speciation- reproductive isolation of populations(gene flow significantly reduced) and genetic divergence(divergent evolution) Tuesday feb 5 Convergent evolution- no common ancestor with that trait, similar environmental things caused the same evolution Divergent evolution- comes from common ancestors but over time the trait changes Proto means before External barriers

Skin-physical barrier to microbial entry, inhospitable environment for growth; dry, dead cells at surface ; sweat/sebaceous glands secreting acids and natural antibiotics like lactic acid Mucuous mebranes of respiratory and digestive tracts well-defined; secretions have antibacterial enzymes Cilia-line the inside of trachea; epithelial cells-smokers cough is from lack of cilia Stomach; if microbes are swallowed, acids(low pH) and protein-digesting enzymes destroy them Lines of defense:

Nonspecififc internal defense: Phagocytosis cells: white blood cells in extracellular fluid, amoeboid shape,destroy microbes by phagocytosis-search out bacteria, viral particles, cellular debris-produced in bone marrow. Target stuff that is not in your cells **questions about lymphatic system on exam natural killer cells- white blood cells that destroy body cells infected by viruses and cancerous cells by punching hole in them inflammatory response- caused by large scale microbial invasion through a wound istamine released in response to damage which leads to an increased blood flow at and around the wound in order to wash out the wound. Which leads to inflammation other chemicals-> macrophages blood clotting fever= response to microbes establishing major infection. Low grade fever 100-102 can be beneficial slows down microbial reproduction enhances immune system immune response- reaction to specific type of microbe and provides future protection.

Involves 2 types of WBC called lymphocytes-B cells and T cells B cells mature in bone marrow T cells are born in marrow but mature in thymus /26/13 humeral cells is same as B cells its called specific immune response because only the cell with the appropriate antibody responds 23,00 coding genes in our genome 3 types of amino acids- hydrophilic, hydrophobic, and ones that can make hydrosulfide bridges most proteins form well with other proteins an antibody is made of four different types of proteins so it takes 4 specific proteins for it to react? Immune system distinguishes self from non self by destroying cells that respond to the body’s own molecules Body randomly makes 100,000,000 different antibodies antigen can bind to 1 specific antibody epitope- the three different site where antibodies can bind on a single antigen allergies: type of immune response allergen-recognized as a foreign antigen and binds to B cell – coordinated by the humoral immunity response B cell makes plasma cells, releasing allergy antibodies into the bloodstream

Antibodies bind to histamine-containing cells in connective tissue Cells release histamine causing inflammatory response such as mucus 1. irst exposure to pollen stimulates B cells to produce allergy plasma cell 2. plasma cells produce allergy antibodies 3. allergy antibodies bind to mast cells 4. re-exposure to pollen results in pollen binding to allergy antibodies on mast cells 5. binding f pollen stimulates mast cells to release histamine, triggering the inflammatory response allergy medication antihistamines others inhibit production of histamine producing cells people without allergies lack genes for allergy-causing antibodies, or produce less of the antibody ormation of a pimple acne develops as a result of blockages In follicles formation of a plug or keratin and sebum(made of fat and the debris of dead fat-producing cells) the natural occurring bacteria propionibacterium acnes can cause inflammation the white blood cells build up(forming a whitehead) and then destroy (by phagocytosis) the bacteria to prevent infection chicken pox and shingles caused by same virus symptoms are very different after you have had the chicken pox, you become immune to the virus.

It is impossible that you may have a slight reaction after re-exposure, such as a few spots and a slight fever. However, you will not get a full blown case of chicken pox more than once shingles: causing agent for herpes zoster is varicella zoster virus, a double stranded DNA virus most people are infected with this virus as children, and suffer from an episode of chickenpox the immune system eventually eliminates the virus from most locations, but it remains dormant in the ganglia adjacent to the spinal cord or the ganglion semilunare in the base of the skull

Free Essays

Biology A2

UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS General Certificate of Education Advanced Level * 2 3 0 8 9 6 9 9 7 3 * BIOLOGY Paper 5 Planning, Analysis and Evaluation Candidates answer on the Question Paper. No Additional Materials are required. READ THESE INSTRUCTIONS FIRST Write your Centre number, candidate number and name on all the work you hand in. Write in dark blue or black ink. You may use a pencil for any diagrams, graphs or rough working. Do not use staples, paper clips, highlighters, glue or correction fluid. DO NOT WRITE IN ANY BARCODES. Answer all questions.

At the end of the examination, fasten all your work securely together. The number of marks is given in brackets [ ] at the end of each question or part question. 9700/51 October/November 2011 1 hour 15 minutes For Examiner’s Use 1 2 Total This document consists of 8 printed pages. DC (CB (SE/DJ)) 34786/4 © UCLES 2011 [Turn over 2 1 Photosynthesis was investigated in a species of unicellular alga using the apparatus shown in Fig. 1. 1. suspension of unicellular algae in water For Examiner’s Use 10. 0 light of known wavelength oxygen probe magnetic stirrer Fig. 1. Two different strains of the species of alga were tested using a range of different wavelengths of light. • • Light of known wavelength was passed through the tube containing algae for two hours. The light transmission through the suspension and the oxygen concentration were then measured. light meter oxygen meter The results were used to plot the absorption spectrum and the action spectrum for each strain of alga. Fig. 1. 2 shows these spectra. strain A strain B absorbance absorption spectra 400 500 600 700 wavelength of light / nm rate of photosynthesis action spectra 400 500 600 700 wavelength of light / nm Fig. . 2 © UCLES 2011 9700/51/O/N/11 3 (a) (i) State the two dependent variables in this investigation. 1. ……………………………………………………………………………………………………………… 2. ………………………………………………………………………………………………………….. [2] (ii) Apart from temperature and pH, which have little effect, state two variables that should be standardised during this investigation. 1. ……………………………………………………………………………………………………………… . ………………………………………………………………………………………………………….. [2] (b) (i) Water with no suspended algae transmits 100% of the light. State how the data to plot the absorption spectrum was obtained. …………………………………………………………………………………………………………………. …………………………………………………………………………………………………………….. [1] (ii) State the data which would be used to plot the action spectrum. ……………………………………………………………………………………………………………. [1] The photosynthetic pigments of the algae were extracted and were separated by two-way chromatography. The pigments were first separated by one solvent and then separated again by a second solvent at right angles to the first solvent. Fig. 1. 3. shows the results for the two different strains. strain A solvent front 1 4 3 2 direction of first solvent 1 origin 6 1 origin 5 3 2 6 strain B 5 solvent front 1 For Examiner’s Use solvent front 2 direction of second solvent Fig. . 3 solvent front 2 (c) Using the information in Fig. 1. 3, suggest why using two different solvents gives a better separation of these pigments than just using one solvent. ………………………………………………………………………………………………………………………… ………………………………………………………………………………………………………………………… ………………………………………………………………………………………………………………………… ……………………………………………………………………………………………………………………….. ……………………………………………………………………………………………………………………. [2] © UCLES 2011 9700/51/O/N/11 [Turn over 4 (d) Outline a procedure that a student could use to extract the photosynthetic pigments and obtain these chromatograms. ………………………………………………………………………………………………………………………… ……………………………………………………………………………………………………………………….. ………………………………………………………………………………………………………………………… ………………………………………………………………………………………………………………………… ………………………………………………………………………………………………………………………… ……………………………………………………………………………………………………………………….. ………………………………………………………………………………………………………………………… ………………………………………………………………………………………………………………………… ………………………………………………………………………………………………………………………… ……………………………………………………………………………………………………………………….. ………………………………………………………………………………………………………………………… ………………………………………………………………………………………………………………………… ………………………………………………………………………………………………………………………… ……………………………………………………………………………………………………………………….. ………………………………………………………………………………………………………………………… ………………………………………………………………………………………………………………………… ………………………………………………………………………………………………………………………… ……………………………………………………………………………………………………………………….. ………………………………………………………………….. ……………………………………………………. ………………………………………………………………………………………………………………………… ………………………………………………………………………………………………………………………… ……………………………………………………………………………………………………………………….. ………………………………………………………………………………………………………………………… ………………………………………………………………………………………………………………………… ……………………………………………………………………………………………………………………. [8] For Examiner’s Use UCLES 2011 9700/51/O/N/11 5 (e) Different photosynthetic pigments absorb different wavelengths of light. Table 1. 1 shows some information about the pigments, P, Q, R, S and T, found in these unicellular algae, including the wavelength of light at which maximum light absorption occurs. Table 1. 1 pigment wavelength of light / nm 620 545 and 547 420 and 660 490 430 and 645 Rf value solvent 1 0. 20 0. 60 0. 65 0. 91 0. 82 solvent 2 0. 89 0. 29 0. 11 0. 19 0. 92 For Examiner’s Use P Q R S T Rf = distance moved by pigment distance moved by solvent front

One of the strains of algae lacks one of the pigments. Using the information in Table 1. 1, Fig. 1. 2 and Fig. 1. 3: (i) identify the strain of alga that lacks one of these pigments and state the letter of the missing pigment …………………………………………………………………………………………………………….. [1] (ii) state the evidence that supports your answer to (i). …………………………………………………………………………………………………………………. ………………………………………………………………………………………………………………… …………………………………………………………………………………………………………………. …………………………………………………………………………………………………………….. [2] (iii) In water, the shorter the wavelength of light, the deeper it travels. Suggest why it is an advantage to have the pigment that you identified in (i). ………………………………………………………………………………………………………………… …………………………………………………………………………………………………………………. …………………………………………………………………………………………………………………. …………………………………………………………………………………………………………….. [1] [Total: 20] © UCLES 2011 9700/51/O/N/11 [Turn over 2 A student carried out some investigations into the inheritance of body colour and wing length in the fruit fly, Drosophila melanogaster, to test the hypothesis: The inheritance of body colour and wing length in fruit flies is controlled by two genes on separate chromosomes. The student carried out three genetic crosses. To carry out each cross the following procedure was used: • • • male and virgin female adult fruit flies were placed into a breeding unit containing a culture medium for their larvae after mating and egg laying, the adult fruit flies were removed newly emerged adult fruit flies were sexed by observing the shape of the last

Free Essays

Biology Investigation

Biology Investigation Aim: to investigate the effects of light and gravity on the growth of sunflower seeds. Background Info: Tropism is directional movement in response to a directional stimulus eg light or gravity. Plants are not able to relocate if they happen to start growing where conditions are nor perfect but they can alter their growth towards more favorable conditions. Plants respond to light (phototropism) where the stems grow towards the light and the roots grow away from the light. They also respond to gravity (geotropism) where the stems grow away from the ground and the roots grow towards the ground.

Tropisms are controlled by auxins – a family of hormones that promote (and sometimes inhibit) growth. Sunflower seeds need regular watering in order to provide sufficient nutrients and ensure healthy and efficient growth. Hypothesis: I hypothesise that whatever orientation the seed is placed in, the shoot will always be positively phototropic and the root will always be positively geotropic, due to the basic laws of tropism. Risk Assessment: Hazard| Risk| Precautions/Disposal| Test tube breakage| Glass may cause injury to eyes or skin. | Be cautious when handling test tube; wear safety equipment such as safety glasses and gloves.

Place in glass bin. | Puncturing boxes with scissors| Scissors may injure someone if there is an accident. | Assign somebody to hold the box steadily while they are being punctured. | Using forceps| May injure skin. | Hold forceps steady and try to avoid contact with skin. | Equipment: Geotropism * 4x large test tube * 4x filter paper * 4x sunflower seed * 1x test tube rack Phototropism * 1x cardboard box * 4x sunflower seed * 1x pair of scissors * 1x forceps * 4x test tube * 4x filter paper * 1x test tube rack Variables: Geotropism * Independent variable: orientation of sunflower seed Dependant variable: direction of growth of sunflower seed shoot and root * Constant variables: the test tube in which the seeds are kept, the place the test tube rack sits, the orientation of each seed Phototropism * Independent variable: orientation of sunflower seed, place of light source * Dependant variable: direction of growth of sunflower seed shoot and root * Constant variables: the box in which the seeds are kept, the place the box sits, the orientation of each seed, the materials used (filter paper, large test tube, test tube rack) Experimental Control: Geotropism

One of the test tubes was set up with a sunflower seed and the shoot facing up, the natural orientation. Phototropism A cardboard box was set up with hole punctures in the top and sides to allow light to get to the plants from all directions. Method: Geotropism * Collect equipment * Set up 4 large test tubes in a test tube rack and label them A, B, C and D. * Soak the 4 filter papers under water * Roll up one filter paper and place in test tube A, along with the sunflower seed shoot facing up to be the control. * Repeat step 4 but with test tube B, with the sunflower seed shoot facing down. Repeat step 4 but with test tube C, with the sunflower seed shoot facing right. * Repeat step 4 but with test tube D, with the sunflower seed shoot facing left. 1. Place in an area with adequate natural light 2. Water every day for 5 days, taking observations on the direction and length of growth on the seeds. Phototropism 1. Collect equipment 1. Set up 4 large test tubes in a test tube rack 1. Soak the 4 filter papers in water 1. Roll up filter paper and place in test tubes, along with the sunflower seeds with all shoots facing upward. 1. Label 3 cardboard boxes as 1. control, 2. eft, 3. right 1. Puncture 10 holes in both sides and the top of box 1 2. Puncture 10 holes in the left side of box 2 3. Puncture 10 holes in the right side of box3 4. Place a test tube rack in each box 5. Place in an area with adequate natural light 6. Water every day for 5 days, taking observations on the direction and length of growth on the seeds. Discussion During the experiment, it was observed that sunflower seed shoots, regardless of their orientation, will almost always grow towards the light. Likewise, the root of the seeds will almost always grow towards the ground.

This trend is due to the auxins in the plant, hormones that promote growth. When a seed is placed sideways, unnaturally, the auxins in the plant stimulate growth in the shoot to still curve upward towards the light, and in the root to curve downward towards the ground. The accuracy of this experiment was sound. The equipment used was the same for all groups and was reasonably suitable to the experiment as it allowed easily observable results, for example the glass test tubes allowed us to watch our seeds grow each day. However, watering the plants was not undertaken every day, affecting the overall accuracy.

Having a specific required amount of water to water the plants each day would have been beneficial to the accuracy of the experiment. The reliability of this experiment was poor. Most observations were not consistent. In many geotropism experiments, there were shoots that did not curve all the way down to the ground. This could have been due to the limited space they had between the glass of the test tube and the filter paper. The validity of this experiment was also poor. The constant variables were not very well controlled; the place in which the apparatus was set up changed, which meant different environmental conditions for the plants.

The weather also changed every day, especially on Saturday when it was 41 degrees. This would have had an impact on the growth of the plants, and a burnt filter paper was observed, which could have been a result of the hot weather. The significant rise in temperature should have been predicted prior to the end of the school week so a more controlled environment could be created for the plants to have a consistent area to thrive in. To improve the accuracy and reliability of this experiment, a clearer and more specific method should be undertaken and a better set up of apparatus should be hought up to give the seeds more room to grow. However, the aim of investigating the effects of light and gravity on the growth of sunflower seeds was answered. This experiment is beneficial to society as it may assist gardeners, florists, other biologists etc in growing plants efficiently. Conclusion: Based on observations, our hypothesis of the shoot always being positively phototropic and the root being positively geotropic was supported, bringing us to the conclusion that light and gravity have a major impact on the growth of sunflower seeds no matter what the orientation.

This is controlled by the auxins that respond to the light and gravity, promoting growth in the shoot of the seed to grow toward the light, and the root of the seed to grow toward the ground. Bibliography: Kimball, J W 2011, Tropisms, viewed 27 November, 2012, <http://users. rcn. com/jkimball. ma. ultranet/BiologyPages/T/Tropisms. html >. Unknown, 2001, Plant Hormones, viewed 27 November, 2012, <http://www. biology-online. org/3/5_plant_hormones. htm> >.

Free Essays

Microbiology Chapter 1 Study Guide

Chapter 1 Notes * Robert Hooke * Discovered Cellulae (Cells) * Formed Basis of Cell Theory * 1. Cell basic unit of life * 2. All living organisms are made of cells * 3. Must have living cells to make more cells * Anton Von Leeuwenhoek * Father microbiology & microscopy * Discovered microorganisms (animalcules) * Disproved microorganisms were heaven sent * Put clean bowl out during rainstorm & no microorganism * Let sit * Days later microorganisms formed from air * Ferdinand Cohn Discovered endospores (enable some bacteria to survive adverse environmental conditions) * Why growth occurred in experiments that disproved/proved SG * Louis Pasteur * Definitive experiment that disproved SG * Fermentation * Pasteurization: heat liquid to temp. that kills the most heat resistant pathogen but NOT all (milk) * Vaccination against Rabies (Rhabdovirus), anthrax (bacillusanthracis), Chicken Cholera (bacterium) * Silkworm industry * Disease (protozoan) was killing silk moths * Developed a method to detect diseased moths and separate * Lady Mary Montagu * Wife British Ambassador to Turkey * Developed Smallpox Observed Turkish women engrafting * Spread mild small pox to other by injecting into their veins * Patient would then be immune to smallpox * Reject because she was woman & not doctor/scientist * Carl Linnaeus * Developed science of taxonomy * Scientific Nomenclature * Binomial nomenclature * Process of giving all organisms 2 scientific names * Genus species * Edward Jenner * Discovered process of vaccination * Worked with cowpox & milkmaids * Milk cowpox scrap pustal scratch skin w/ needle develop mild cowpox immune to smallpox * John Snow * First epidemiologist Traced Cholera epidemic to common H2O pump that was contaminated * Ignaz Semmelweis * Puerperal Fever (child bed fever) major cause of mortality to mothers and infants * Death in midwife ward = low ; death in doctor/med student ward = high * Doctors/med students contact w/ cadavers that previously died from disease * Spread disease to living mothers * Required hand washing with chlorite of lime * Joseph Lister * Concerned with incidence of infection and mortality from surgery * Aseptic Surgery = used carbolic acid (phenol) on incision site, instruments, and bandages * John Tyndall Boiling was not sufficient to sterilize broths and agar * Tyndallization Process: * Liquid is heated to boiling (100°C) allowed to sit and cool for 24hours * Liquid is reheated to boiling (100°C) and then allow to cool and sit for another 24 hours * Repeat * Robert Koch * Developed concept of causative agent of disease (MO cause disease) * Germ Theory of Disease – developed many microbiological techniques, media and procedures * Tuberculin – thought founded vaccine (incorrect) .. use as first step to determine if person has TB * Fanny Hesse * Worked for Robert Koch Used Agar to convert liquid brother to slid medium * Koch’s Postulates (Identifying which bacteria causes which disease) * MO must be present in every case of the disease. Every host must have the same signs and symptoms of the disease * Isolate the microorganism and grow it in pure culture outside the host * Pure culture must be inoculated into a healthy susceptible host. Experimentally infected host must exhibit the same signs and symptoms of the disease * The Microorganism must be reisolated from the experimentally infected host and shown to be identical to the original MO * Paul Ehrlich Concept chemotherapy * Syphilis – Treponema palladium * Compound 606-Salvarsan (Arsenic containing compound) * Alexander Fleming * Accidently discovered antibiotics * Antibiotics = naturally produced compounds that inhibit the growth of other MOs * Working with Staphylococcus aureus (opportunistic pathogen- must be proper conditions to cause infection) * Most antibiotics produced by bacteria, followed by fungi * Martinus Beijerinck * Concept of Viruses * Soil microorganisms-isolated the first soil MOs * Sergei Winogradsky * Sulfur metabolism by microorganisms * Concept of nitrogen fixation * Biochemical cycles Symbiotic relationships * Barbara McClintock * Transposons – cause Maize (jumping genes- genes move themselves and create different color kernals) * James Watson, Francis Crick, Rosalind Franklin and Maurice Wilkins * Structure of DNA * Molecular biology and genetics * Thomas Brock * Thermophilic microorganisms (high temperature loving microorganisms) * Thermus and Sulfolobus * Lynn Margulis * Endosymbiont Theory * Big prokaryotic cell engulfs little prokaryotic cell * Little survives insides but loses many functions (energy conversion, protein synthesis) * Little becomes mitochondria or chloroplast Eukaryotic Cell evolved * Carl B. Woese * Molecular systematic based on 16sRNA * Improved ability to identify MO * Stanley Prusinier * Discovered Prions * Protenaous Infectious Particles * Luc Montagnier * Discovered human immunodeficiency virus * Barry Marshall and Robin Warren * Causative agent of gastric & peptic ulcers * MO colonize in stomach * Disbelieved b. c stomach is so acidic and has enzymes * Antibiotics cure ulcers * Demonstrated effect pharmaceutical industry & practice of gastroenterology against 2 men