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Bio ch 25
| Question | Answer |
|---|---|
| 4 stages of the origin of life | 1. abiotic synthesis of small organic molecules 2. formation of macromolecules 3. packaging into protocells 4. self replicating molecules (RNA) |
| what was Earth's early atmosphere like | reducing (ch4, nh3, h2, h2o vapor), little or no o2 |
| why was there little to no oxygen on early earth | no photosynthetic organisms yet |
| what energy sources powered early chemical reaction | lightning, UV radiation, volcanic activity |
| what did miller-urey test and what did his experiments show | he tested abiotic synthesis of organic molecules his experiments shows that organic molecules (amino acids) can form under early earth conditions |
| what's a protocell | membrane bound structure that forms spontaneously and can: maintain internal chemistry separate inside from outside shw simple metabolism like processes was the bridge between nonliving chemistry and living cells |
| what's a ribozyme | RNA molecule that acts as an enzyme |
| why is RNA world important | RNA can both store info and catalyze reactions |
| what were the first organisms on earth and when | prokaryotes, 3.5 bya |
| what did cyanobacteria do | performed photosynthesis which released oxygen |
| what was the effect of oxygen accumulation | toxic to many anaerobes led to evolution of aerobic respiration enabled eukaryotes |
| evidence for endosymbiosis | own circular dna double membrane ribosomes like bacteria divide independently |
| endosymbiosis | theory that eukaryotic cells formed when one cell engulfed another which led to mutual relationship |
| what is adaptive radiation | periods of evolutionary change causes formation of new species whose adaptations allow them to fill ecological roles and niches in their communities |
| why is RNA through to be the first genetic material | can store genetic info can act as an enzyme (ribozyme) can self replicate |
| why is fossil record incomplete | fossilization is rare and biased towards organism with hard parts (bones and shells) and organisms in certain environments, also if more abundant and lived longer there's more fossils |
| what's relative dating | determining the order of events using rock layers, older layers are deeper |
| what radiometric dating | determining absolute age using radioactive decay of isotopes |
| what's a half life | time required for 50% of a radioactive isotope to decay |
Created by:
Lilyhowes