A gene pool consists of: a. alleles for a gene that all confer the same fitness b. the total of all alleles present in a population c. the entire genome of an individual of reproductive age d. all of the gametes in a population e. All of the above are correct
b. the total of all alleles present in a population
Evolution is defined as: a. a change in the frequency of alleles in a population over time b. a change in the frequency of a physical trait in a population over time c. a progressive "ladder" of changes from most primitive organisms to most advanced organisms d. a change in a physical trait of an individual during its lifetime e. a change in the frequency of the genome in the community over time
a. a change in the frequency of alleles in a population over time
Which of the following statements about mutations is FALSE? a. Mutations are the ultimate source of all genetic variability b. Mutations always decrease an organism's fitness c. Somatic cell mutations do not lead to evolution d. Mutations can be induced via ultraviolet radiation e. Mutations occur in all species
b. mutations always decrease an organism's fitness
All northern elephant seals come from a very small genetic pool. This is because in the 1890s a large number of them were very quickly killed until their population size was reduced to only about 20 individuals. Though their population has since increased to over 30,000 individuals, all their genes have come from those 20 individuals. Which of the following population genetic concepts does this example represent? a. the founder effect b. the bottleneck effect c. the Hardy-Weinberg equilibrium d. genetic drift
b. the bottleneck effect
Genetic drift is best described as: a. evolutionary change due to natural selection b. evolutionary change due to random events c. changes in the proportion of homozygous recessive individuals due to non-random mating d. changes in the proportion of homozygous recessive individuals due to random mating e. a random change in allele frequencies that benefits the population
e. a random change in allele frequencies that benefits the population
Consider a population of 5000 garter snakes. Two hundred of those snakes split off from the population to a new habitat. When the original population dropped from 5000 to 4800, the allele frequencies of various genes changed. The evolutionary process that caused the change in allele frequencies in the original population is: a. migration b. genetic drift c. mutation d. stabilizing selection
a. migration
To establish that evolution by natural selection is operating in a population, one must demonstrate variability for a trait, heritability of that trait, differential reproductive success based on that trait, and: a. continuous change in the environment b. progress c. random mating d. increased complexity of the organism e. nothing else
e. nothing else
Many mosquito populations today are resistant to pesticides that were historically effective. This pesticide resistance arose in these populations because: a. the pesticides caused mutations in the DNA of mosquitoes that conferred resistance phenotypes, and were passed on to subsequent generations b. populations had to develop tolerance in order to survive c. individual mosquitoes build up immunity to the pesticides after exposure d. some individuals were resistant to the pesticides before they were used, and those mosquitoes were more likely to survive and reproduce
d. some individuals were resistant to the pesticides before they were used, and those mosquitoes were more likely to survive and reproduce
An oak tree produces two kinds of leaves: large with shallow lobes and narrow with deep lobes. If this dimorphism is based solely on the ecological condition of amount of sunlight exposure and there is no genetic difference between leaves that express either of the two forms, then: a. the environment cannot affect the relative abundance of the two leaf forms b. this must be a trait that expresses quantitative variation c. natural selection cannot preferentially select one of the two leaf forms over the other d. the large, shallow-lobed leaves must be adapted for sunnier conditions
b. this must be a trait that expresses quantitative variation
An organism's fitness is measured: a. relative to other genotypes/phenotypes in the population b. only for a specific environment c. by reproductive success d. for a given point in time e. All of the above
c. by reproductive success
Brassica oleracea was a European wild plant. Early farmers were able to use artificial selection on this plant to produce cabbage, brussels sprouts, kohlrabi, kale, broccoli, and cauliflower. This diversification through selection was possible because: a. the species contained large amounts of genetic variation b. artificial selection is always possible, whereas natural selection requires much larger population sizes c. artificial selection does not require differential reproductive success, whereas natural selection does d. exotic species are always more adaptable than the native species in an area
a. the species contained large amounts of genetic variation
A breeder of thoroughbreds selects only the fastest horses for breeding stock. This is an example of artificial ____________ selection. a. Directional b. Disruptive c. Sexual d. Stabilizing
a. directional
Which of the following is not a source of evidence demonstrating the occurrence of evolution? a. the fossil record b. biogeography c. comparative anatomy and embryology d. molecular biology e. all of the above are sources of evidence demonstrating the occurrence of evolution
e. all of the above are sources of evidence demonstrating the occurrence of evolution
Which of the following is a limitation to using the fossil record to study evolution? a. Fossils only form under a very specific and rare set of environmental conditions b. Since the formation of fossils only occurs under extremely high pressures, only fossils of marine organisms are preserved c. Since fossils are found in rocks on land, only fossils from terrestrial species exist d. Because fossils must be embedded within rocks, only the soft parts of organisms can become fossilized
a. fossils only form under a very specific and rare set of environmental conditions
__________________ isolating mechanisms include hybrid mortality and hybrid infertility. a. Prezygotic b. Postzygotic c. Sympatric d. Biochemical
b. postzygotic
Which of the following is NOT a difficulty with the biological species concept? a. fossil SWS b. asexual species c. hybridizing species d. inbreeding species
a. fossil SWS
Speciation without geographic isolation is called: a. allopatric speciation b. sympatric speciation c. autopatric speciation d. parapatric speciation
b. sympatric speciation
Nodes on an evolutionary tree represent both common ancestors and: a. speciation events b. branches c. convergent traits d. hybridization events e. analogous traits
b. branches
All mammals have hair because they inherited that trait from a common ancestor. Features that are inherited from a common ancestor are called: a. homologous features b. analogous traits c. convergent features d. independent traits
a. homologous features
In comparing the streamlined nature of a dolphin and that of a shark, you conclude that the streamline feature evolved independently in sharks and dolphins. This common characteristic most likely is the result of: a. Homology b. convergent evolution c. highly similar DNA sequences d. descent from a recent common ancestor
b. convergent evolution
The honeycreepers are a group of Hawaiian birds with many different species that all evolved from a single species that migrated from the Americas. Which pattern of evolution is the speciation of the honeycreepers most likely to be an example of? a. convergent evolution b. adaptive radiation c. convergent radiation d. allopolyploiody
b. adaptive radiation
The number of individuals that can be supported in a given habitat is the: a. biotic potential b. density-dependent effect c. carrying capacity d. density-independent effect
c. carrying capacity
Which of the following is NOT an example of a density-dependent limiting factor that will influence carrying capacity? a. food supply b. predation c. disease d. territory availability e. flooding
e. flooding
The death rate of organisms in a population exhibiting a type 3 survivorship curve is: a. lower after the organisms survive to the critical age of establishment b. more or less constant throughout their lives c. higher in post-reproductive than in pre-reproductive years d. usually correlated with disease e. usually correlated with density-independent causes
a. lower after the organisms survive to the critical age of establishment
Which of the following is NOT true about life history patterns in general? a. The longer a species lives, the more offspring they are likely to leave behind b. The greater the average size of offspring, the fewer offspring are produced in a mating c. The fewer the reproductive events, the longer individuals are likely to live d. The greater the investment in reproduction, the longer a species is likely to live e. Growth is slowed during periods when reproduction occurs
a. the longer a species lives, the more offspring they are likely to leave behind
Natural selection: a. leads to an increase in the frequency of any illness-inducing alleles that have their effect when an organism can reproduce b. can influence aging but not longevity c. cannot reduce the frequency of alleles that cause mortality among individuals who have not yet reached the age of maturity d. does not influence aging because aging is determined by an individual's environment e. cannot weed out from a population any alleles that do not reduce an individual's relative reproductive success, even if these alleles increase an individual's risk of dying
e. cannot weed out from a population any alleles that do not reduce an individual's relative reproductive success, even if these alleles increase an individual's risk of dying
Studies of human demography have revealed that: a. preindustrial countries usually have low birth rates b. developing countries in the process of becoming industrialized tend to have high death rates c. countries with higher levels of education and employment have low birth rates d. post-industrialized countries have high birth rates e. countries with efficient systems of food production and distribution have low death rates
c. countries with higher levels of education and employment have low birth rates
Latitudinal banding of tropics, deserts, temperate and polar climates is best explained by: a. rain shadows b. atmospheric circulation patterns c. the Coriolis effect d. the tilt of earth's axis e. oceanic circulation patterns
b. atmospheric circulation patterns
An ecosystem consists of ____________________ in a given area. a. all the photosynthetic organisms b. all the living organisms c. all the abiotic factors that influence living organisms d. all the living organisms and all the abiotic factors that influence living organisms
d. all the living organisms and all the abiotic factors that influence living organisms
A(n) ________ describes the area in which an organism lives, whereas a(n) _________ describes all of the organisms in a particular area at a particular time. a. ecosystem; population b. habitat; community c. biome; ecosystem d. habitat; biota e. ecosystem; community
b. habitat; community
The 10% rule of energy conversion efficiency: a. explains why big, fierce animals are so rare b. explains why herbivore biomass must exceed that of carnivores c. limits the length of food chains d. suggests that 90% of what an organism eats is used in cellular respiration or is lost as feces e. All of the above are correct
e. all of the above are correct
The nitrogen cycle is important biologically because: a. nitrogen is a component of amino acids, proteins, and nucleic acids b. nitrogen forms the framework for organic molecules essential to all organisms c. nitrogen is a major constituent of phospholipids, ATP, and other energy-storing molecules d. photosynthesis by plants and phytoplankton remove substantial amounts of atmospheric nitrogen
a. nitrogen is a component of amino acids, proteins, and nucleic acids
Which of the following statements about an organism's niche is INCORRECT? a. It encompasses the space the organism requires b. It includes the type and amount of food the organism consumes c. It is not always fully exploited d. It may be occupied by two species, as long as they are not competitors e. It reflects the ways in which the organism uses the resources of its environment
d. it may be occupied by two species, as long as they are not competitors
In a food web consisting of grass, grasshoppers, sparrows, and hawks, the sparrows are: a. primary producers b. primary consumers c. secondary consumers d. tertiary consumers
c. secondary consumers
The "life-dinner hypothesis" proposes that: a. selection for capture ability in the predator is stronger than selection for escape ability in the prey b. selection for escape ability in the prey is stronger than selection for capture ability in the predator c. finding food is more important in life than any other behavior d. to maintain good health, dinner is the most important meal e. when two species battle for resources in the same niche, one will be driven to local extinction
b. selection for escape ability in the prey is stronger than selection for capture ability in the predator
Small fish often follow large turtles in the open ocean, taking advantage of the turtle as a place to hide. This interaction would best be classified as: a. Mutualism b. Parasitism c. Commensalism d. Predation
c. commensalism
The chief difference between primary and secondary succession is that: a. primary succession occurs among the plants in a habitat, while secondary succession occurs among the animals in a habitat b. primary succession begins with no life or soil, while secondary succession begins with both c. secondary succession alters the biotic environment and primary succession alters the abiotic environment d. primary succession occurs more quickly than secondary succession e. primary succession can occur in terrestrial and aquatic habitats, while secondary succession can occur only in terrestrial habitats
b. primary succession begins with no life or soil, while secondary succession begins with both
Which of the following is most likely to lead to the highest levels of biodiversity? a. the presence of a climax community b. the presence of a colonizer community c. the presence of a keystone predator d. frequent disturbance of an ecosystem
c. the presence of a keystone predator
Which of the following statements most directly explains the presence of deserts like the Mojave in California? a. The greater the altitude, the greater the air pressures b. Cities like Los Angeles absorb and pass on heat to nearby localities c. Cities channel hot air from the west into eastern localities d. A chain of mountains create a rainshadow e. Dry ocean currents remove moisture from land nearby
d. a chain of mountains create a rainshadow
Earth's largest ecosystems, biomes, are defined primarily by: a. the average rainfall b. the average temperature c. the seasonal variability in temperature d. the seasonal variability in rainfall e. All of the above
e. all of the above
The loss of tropical rainforest causes a decrease in biodiversity because: a. tropical rainforests are only found at high latitudes b. tropical rainforests produce acid rain when they are burned c. tropical rainforests decrease greenhouse gases d. tropical rainforests offer very diverse terrestrial habitats e. tropical rainforests prevent the release of toxic metals like mercury
c. tropical rainforests decrease greenhouse gases
Which of the following is a major contributor to the biodiversity found in any particular region on earth? a. available solar energy b. rate of disturbance c. evolutionary history of an area d. All of the above are correct e. Only a) and c) are correct
d. all of the above are correct
The average time to death from starvation in a fruit fly is about 20 hours. Selecting for increased starvation resistance in fruit flies: a. has no effect, because starvation resistance is not a trait that influences fruit fly fitness b. has little effect, because ongoing mutation continuously reduces starvation resistance, counteracting any benefits from selection c. cannot increase their survival time, because there is no genetic variation for this trait d. has no effect, because starvation resistance is too complex a trait, dependent on the effects of too many genes e. can produce populations in which the average time to death from starvation is 160 hours
e. can produce populations in which the average time to death from starvation is 160 hours
Georges Cuvier's discovery of fossils of Irish elk and giant ground sloth: a. supports scientific evidence for extinction b. was possible because of Buffon's determination that the earth was more than 6000 years old c. was possible only following Darwin's publication of "The Origin of Species" d. was made in deep ocean trenches e. suggested that species are immutable
a. supports scientific evidence for extinction
While on the voyage of the HMS Beagle, Darwin: a. wrote "The Origin of Species" b. nurtured his love of studying nature, exploring plant and animal diversity, and collecting fossils c. discovered a love for sea travel d. studied Malthus's book "Essay on Principle of Population" e. corresponded extensively with Alfred Russel Wallace about their ideas on evolution
b. nurtured his love of studying nature, exploring plant and animal diversity, and collecting fossils
Which one of the following statements best describes the difference between artificial and natural selection? a. natural selection is limited to physical traits and artificial selection is not b. artificial selection has produced many of the most delicious food items for humans; natural selection has not c. natural selection acts without the input of humans; artificial selection requires human input d. Charles Darwin understood natural selection but at that time, was unaware of artificial selection e. natural selection works on all species; artificial selection works only on laboratory-raised species
c. natural selection acts without the input of humans; artificial selection requires human input
Which of the following statements about Charles Darwin is incorrect? a. he spent five years traveling the world, observing living organisms and collecting fossils b. he was under constant pressure from his father to make something of himself c. he dropped out of medical school d. he was enthusiastic about unleashing his theory of natural selection on the world as soon as he thought of it e. he and Alfred Russel Wallace independently came up with the theory of evolution by natural selection
d. he was enthusiastic about unleashing his theory of natural selection on the world as soon as he thought of it
Evolution occurs: a. only when the environment is changing b. only through natural selection c. almost entirely because of directional selection d. only via natural selection, genetic drift, migration, or mutation e. by altering physical traits but not behavioral traits
d. only via natural selection, genetic drift, migration, or mutation
Which of the following statements about mutations is incorrect? a. mutations are almost always random with respect to the needs of the organism b. a mutation is any change in an organism's DNA c. most mutations are harmful or neutral to the organism in which they occur d. the origin of genetic variation is mutation e. all of these statements are correct
e. all of these statements are correct
Genetic drift has the strongest effects in populations that are: a. small b. large c. characterized by extensive gene flow d. in Hardy-Weinberg equilibrium e. undergoing natural selection
a. small
When a group of individuals colonizes a new habitat, the event is likely to be an evolutionary event, because: a. members of a small population have reduced rates of mating b. gene flow increases c. mutations are more common in novel environments d. new environments tend to be inhospitable, reducing survival there e. small founding populations are rarely genetically representative of the initial population
e. small founding populations are rarely genetically representative of the initial population
"Survival of the fittest" may be a misleading phrase to describe the process of evolution by natural selection, because: a. it is impossible to determine the fittest individuals in nature b. survival matters less to natural selection than does reproductive success c. natural variation in a population is generally too great to be influenced by differential survival d. during population bottlenecks, it is the least fit individuals that have the greatest survival e. reproductive success on its own does not necessarily guarantee evolution
b. survival matters less to natural selection than does reproductive success
Evolutionary adaptation: a. refers both to the process by which populations become better matched to their environment and to the features of an organism that make it more fit than other individuals b. cannot occur in environments influenced by humans c. is possible only when there is no mutation d. is responsible for the fact that porcupines are at an unusually high risk of predation e. occurs for physical traits but not behaviors
a. refers both to the process by which populations become better matched to their environment and to the features of an organism that make it more fit than other individuals
Adaptations shaped by natural selection: a. are magnified and enhanced through genetic drift b. are unlikely to be present in humans living in industrial societies c. may be out of date, having been shaped in the past under conditions that differed from those in the present d. represent perfect solutions to the problems posed by nature e. are continuously modified so that they are always matched to the environment in which a population lives
c. may be out of date, having been shaped in the past under conditions that differed from those in the present
Artificial selection was used on corn to produce a single strain of corn with increased growth rates and greater resistance to a fungus. Although farmers have continued to select for these traits, that productivity of this strain is no longer increasing. This suggest that: a. the population size has been decreasing b. all or most of the natural variation for these traits has been eliminated c. gene migration is a major evolutionary agent in corn d. long-term disruptive selection may lead to speciation e. artificial selection is not as strong as natural selection
b. all or most of the natural variation for these traits has been eliminated
In a population in which a trait is exposed to stabilizing selection over time: a. neither the average value nor the variation for the trait changes b. both the average value and the variation for the trait increase c. the average value increases or decreases, and the variation for the trait decreases d. the average value for the trait stays approximately the same, and the variation for the trait decreases e. the average value for the trait stays approximately the same, and the variation for the trait increases
d. the average value for the trait stays approximately the same, and the variation for the trait decreases
Maze-running behavior in rats: a. is too complex a trait to be influenced by natural selection b. is a heritable trait c. is not influenced by natural selection d. shows no variation e. is influenced primarily by mutation in the laboratory
b. is a heritable trait
A fossil is defined most broadly as: a. the preserved pieces of hard parts (e.g., shell or bone) or extinct animals b. any preserved remnant or trace of an organism from the past c. the preserved bones of vertebrates d. a piece of an organism that has turned into rock e. the process of preservation of intact animal bodies
b. any preserved remnant or trace of an organism from the past
Which of the following statements about marsupial mammals is correct? a. they fill many niches in Australia that are occupied by placental mammals in other parts of the world b. they are less fit than placental mammals c. they have become extinct as a result of the greater fitness of placental mammals d. they are more closely related to each other than they are to placental mammals e. both a. and d. are correct
e. both a. and d. are correct
Convergent evolution can occur only when two species: a. have a recent common ancestor b. live in the same geographic area c. are separated by a barrier such as a new river d. evolve under similar selective forces e. are both unpalatable to predators
d. evolve under similar selective forces
What can be concluded about comparing differences in molecular biology between different species? a. extremely different species are fundamentally unrelated in any way b. only DNA sequences can be used to compare relatedness between species c. birds are more closely related to humans than dogs are d. genetic similarities and differences demonstrate species relatedness e. the longer two species have been evolving on their own, the fewer the genetic differences between them
d. genetic similarities and differences demonstrate species relatedness
Evolution: a. occurs too slowly to be observed in nature b. can occur in the wild but not in the laboratory c. is responsible for increased occurrence of antibiotic-resistant bacteria d. does not occur in human-occupied habitats e. none of these statements is correct
c. is responsible for the increased occurrence of antibiotic-resistant bacteria
Why do human taste preferences exist? a. they are culturally generated; consumers are influenced by suggestive advertising b. human feeding choices influence energy intake and, consequently, fitness c. humans can extract energy from a variety of non-food sources, so taste preferences cause us to focus on foods that are more plentiful in our environment d. fats actually do taste better than sugars e. vitamins and minerals give foods unusual tastes, which causes us to seek them out
b. human feeding choices influence energy intake and, consequently, fitness
From an evolutionary perspective, behavior can best be viewed as: a. a trait that arises by learning, not by natural selection b. non-heritable c. a trait subject to drift and mutation, but not natural selection d. part of the phenotype e. all of the above are correct
d. part of the phenotype
Why is it so much easier for an infant to learn a complex language than for a college student to learn biology? a. language involves memorization only, without the need for understanding rules, while biology involves both. b. language is a feature with great evolutionary relevance for humans c. learning biology was not a behavior with evolutionary relevance for humans d. biology involves much more vocabulary than learning a complex language e. both b. and c. are correct
e. both b. and c. are correct
Babies in the US quickly and easily develop a fear of snakes. Yet they don't easily develop a fear of guns. Why? a. humans cannot develop fears of inanimate objects b. evolution can be slow in producing populations that are adapted to their environments c. babies are more likely to encounter snakes than guns as they develop in the US d. fewer individuals are killed by guns than by snakes in the US each year e. all of the above are correct
b. evolution can be slow in producing populations that are adapted to their environments
In Belding's ground squirrels, why are females much more likely than males to engage in altruistic behavior by sounding alarm calls? a. Belding's ground squirrels have a sex ratio that is biased toward females b. females invest more in foraging and food storage, so they are more likely to lose their lives or their food if a predator attacks c. Belding's ground squirrels have a sex ratio that is biased toward males d. females tend to remain in the area where they were born, so the females that call are warning their own kin e. males forage alone, so their alarm calls are useless
d. females tend to remain in the area where they were born, so the females that call are warning their own kin
Gestational diabetes is thought to be the consequence of: a. pregnant women decreasing their average daily amount of activity b. a mother withholding investment in future offspring in order to invest more in the current pregnancy c. a mother consuming too much sugar during gestation d. conflict between the mother and fetus with respect to how much food the fetus should be given; the mother is equally related to the fetus and to any future offspring, while the fetus is not equally related to itself and any subsequent siblings e. physiological constraints on the amount of insulin a mother can provide for the fetus
d. conflict between the mother and fetus with respect to how much food the fetus should be given; the mother is equally related to the fetus and to any future offspring, while the fetus is not equally related to itself and any subsequent siblings
Vampire bats: a. sometimes regurgitate blood into the mouth of another bat that is close to starving, but the likelihood is a function of whether the individuals are genetically related b. are unusual in that they are one of the few animal species that exhibit kin selection c. sometimes regurgitate blood into the mouth of an unrelated bat that is close to starving d. exhibit reciprocal altruism but not kin selection e. there are no such things as vampire bats; they're found only in a Dracula novel
c. sometimes regurgitate blood into the mouth of an unrelated bat that is close to starving
Altruistic behavior in animals may be a result of kin selection, a theory maintaining that: a. genes promote the survival of copies of themselves when behaviors by animals possessing those genes assist other animals that share those genes b. aggression within sexes increases the survival and reproduction of the fittest individuals c. companionship is advantageous to animals because in the future, they can recognize those that have helped them and provide help to those individuals d. aggression between the sexes increases the survival and reproduction of the fittest individuals e. companionship is advantageous to animals because, in the future, they can recognize those that have helped them and request help once again
a. genes promote the survival of copies of themselves when behaviors by animals possessing those genes assist other animals that share those genes
All of the following conditions are necessary for reciprocal altruism to evolve in a species except: a. the ability to recognize different individuals b. the ability to punish cheaters who do not reciprocate c. repeated interactions with the same individuals d. at least one of the sexes must not disperse so that some individuals always live near their kin e. none of the above is necessary for the evolution of reciprocal altruism
d. at least one of the sexes must not disperse so that some individuals always live near their kin
In a situation in which males guard eggs and care for the young without help from the female, which of following statements would most likely be correct? a. males are large and more brightly colored in order to attract the very best females b. males and females are equally brightly colored, but males court females aggressively c. the population is monogamous with no sexual dimorphism d. a single male controls a harem of females to which he has exclusive reproductive access e. females are more brightly colored than males and court males aggressively
e. females are more brightly colored than males and court males aggressively
In mammals, as well as many other species, males generally compete for females. The best explanation for this phenomenon is: a. males are more aggressive b. males, on average, have higher fitness c. females have a higher parental investment d. males are choosy e. females are better looking
c. females have a higher parental investment
Mate guarding is a reproductive tactic that functions to: a. reduce paternity uncertainty b. increase the female's investment in offspring c. reduce the male's reproductive investment d. reduce the female's fitness e. increase the number of mates to which a male has access
a. reduce paternity uncertainty
Relative to birds, more mammalian species are: a. polygynous b. monogamous c. polyandrous d. hermaphroditic e. sexually monomorphic
a. polygynous
In a species such as pigeons, in which males are almost indistinguishable in appearance from females, the most likely mating system is: a. monomorphism b. monogamy c. polygyny d. polyandry e. it is impossible to predict the mating system with only this information
b. monogamy
If you find a species of fish in which males are much more brightly colored and larger than females, what might you infer about their mating system? a. the degree of sexual dimorphism does not give any information about the mating system b. they are simultaneous hermaphrodites c. they exhibit parallel monogamy d. they are serially monogamous e. they are polygynous
e. they are polygynous
Polygynous species: a. usually employ external fertilization b. are usually sexually dimorphic, with males larger and more highly ornamented c. are usually sexually dimorphic, with females larfer and more highly ornamented d. usually have males and females that are physically indistinguishable e. are more commonly found among birds than among mammals
b. are usually sexually dimorphic, with males larder and more highly ornamented
In a set of classic experiments performed in the early 1950s, Urey and Miller subjected an experimental system composed of H2, CH4 (methane), and NH4 (ammonia) to electrical sparks. A few days later, they found ________________ in their system. a. amino acids b. DNA c. microspheres d. cells e. RNA
a. amino acids
What kind of molecule is thought to have been the first genetic material? a. protein b. DNA c. carbohydrate d. RNA e. microsphere
d. RNA
According to the biological species concept, species are natural populations of organisms that have the potential to interbreed and that are ______ isolated from other such populations a. behaviorally b. prezygotically c. postzygotically d. geographically e. reproductively
e. reproductively