1. Why did Miller/Urey need the condensor? What were their "raw materials?" What were their
products? 3 points.

2. Explain the differences between a primary heterotroph and a plain heterotroph. How did the primary heterotrophs meet their nutritional requirements? 2 points.

3. As water accumulated on the Earth and began to be utilized as an electron donor through
photosynthesis, what happened to the Earth's atmosphere? In addition, as the Earth's atmosphere changed what happened to the ever present ultraviolet radiation level? Why was the ultraviolet radiation level changed? What is happening now to the amounts of ultraviolet radiation received by the Earth? What do scientists believe has caused this change? What is the evidence? 5 points.

4. Figure 3-8 is the "clock of biological time." Please read the caption beneath the figure. When was oxygen abundant enough to support life on the lithosphere? 1 point.

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