For help with this material, see excellent lecture notes posted here by Bruce Walsh, University of Arizona.
Please be prepared to answer any of the following review questions.
1. How do conditions on Earth today compare with those that likely existed when life originated?
2. How does Earth compare with Mars and Venus in terms of ongoing processes involving water and carbon dioxide? (See Fig. 1.3; also check out this: Mars Quick Facts and here.
3. What are likely sources for organic molecules on early Earth?
4. What four properties does Cowen claim characterize a "living thing"?
5. Why is phosphorus an important constituent of life?
6. What four conditions are necessary if life is to evolve from non-life? How were these conditions likely met on early Earth? [Note: This question was based on a previous edition, where Cowen listed these as energy, protection, concentration, and catalysis. See
7. What evidence is there that amino acids could be formed spontaneously on early Earth? How and where are chains of amino acids formed abiotically (without life)?
8. Why are clay minerals important?
9. What are liposomes (or vesicles)? (Extra challenge: See the article "What came before DNA?" by Carl Zimmer)
10. What are the most likely habitats where life might have evolved?
11. How do the following organisms differ in their metabolism?: 1) fermentors; 2) methanogens; 3) autotrophs utilizing sunlight; 4) autotrophs utilizing other sources
12. What are arguments for or against ancient life on Mars based on the meteorite known as ALH 84001 (see p. 5 or here).
13. What is the significance of the enzyme, superoxide dismutase (SOD)?
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[Go to History of Life listing for Chapter 1]
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