AP Biology / Unit 7: Natural Selection
7.12 Origins of Life on Earth
Notes
Earth is about 4.6 billion years old; life appeared around 3.5 billion years ago.
- Models: organic molecules formed from simple ones (Miller-Urey), then polymers.
- RNA world hypothesis: RNA came first because it stores information and can catalyze reactions.
Practice
The Miller-Urey experiment showed that:
Amino acids formed in the lab.
RNA is a likely first genetic molecule because it can:
Both roles.
Evidence about early life comes from:
Multiple lines of evidence.
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