What was Earth's early atmosphere like?
It contained little or no oxygen
What does Miller and Urey's experiment tell us about the organic compounds needed for life?
It could have appeared from simpler compounds on an ancient Earth
You just read that life arose from nonlife billions of years ago. Could life arise from nonlife today? Why or why not?
No, because the same conditions no longer exist on Earth
What does the endosymbiotic theory propose?
A symbiotic relationship evolved over time, between primitive eukaryotic cells and the prokaryotic cells in them.
According to this theory, how did mitochondria evolve?
From endosymbiotic prokaryotes (that were able to use oxygen to generate energy-rich ATP)
What evidence supports the theory?
Mitochondria contain DNA similar to bacterial DNA. Mitocondria have ribosomes similar to bacteria. Mitochondria, like bacteria, reproduce by binary fission
Why is the development of sexual reproduction so important in the history of life?
Because it increases genetic variation
Put the following events in the order in which they occured: sexual reproduction, development of eukaryotic cells, free oxygen in the atmosphere, and development of photosynthesis
1. Development of photosynthesis
2. Free oxygen in the air
3. Development of eukaryotic cells
4. Sexual reproduction
