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Bio 2 Origin of Life
Bio 155, Exam 2
| Question | Answer |
|---|---|
| Chemical Evolution | inorganic molecules in Earth's prebiotic oceans combined to produce organic molecules and eventually primitive cells |
| 4 Stages of Chemical Evolution | 1) abiotic synthesis of organic monomers 2) abiotic synthesis of polymers from monomers 3) formation of protobionts 4) development of a self-replication system |
| Earth is approximately _______ years old | 4.6 billion |
| Importance of a reducing environment in chemical evolution | reducing environment was necessary to build larger molecules from smaller molecules |
| What molecule was most likely NOT present in the early atmosphere? | O2 |
| The abiotic synthesis of polymers from monomers is conceptually difficult b/c it would have to have been accomplished without ______ and with _________ of precursors. | enzymes; low concentrations |
| favorite 'facilitator' for abiotic polymerization | minerals |
| 2 possibilities for the 'first' protobionts | liposomes, proteinoid microspheres |
| What was the first replication system likely based on? Why? | RNA; RNA is simpler than DNA (ss v ds) and some RNA molecules are auto-catalytic so they could've acted as their own enzymes for replication. |
| Original innovation of life (SECRET OT LIFE) | chemiosmotic mechanism of ATP synthesis |
| necessary condition for appearance of complex multicellular life | sufficiently high atmospheric oxygen (provided by CYANOBACTERIA) |
| When did the first animals appear on Earth? When did life appear on land? | ~600 mya; ~450-500 mya |
| 3 possible biological consequences of continental drift | 1) habitat alteration (more continental shelf when continent breaks up 2) climate change (land mass moves poleward from equator) 3) allopatric speciation (continental break-up separates a population |
| True or False: The majority of species that have ever lived are still extant (still alive). | False |
| # of mass extinction events recognized Which was the worst in terms of extinction rate? | 5; End-Permian extinction, ~250 mya |
| major cause of the end-Cretaceous mass extinction | asteroid impact |
| significance of mass extinctions | large, random, unpredictable events that can have an extremely significant influence on the large-scale pattern of biological evolution |
Created by:
mkroon26
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