1. Diagram the sulfur cycle, label all the fluxes, indicate oxic and anoxic portions of the cycle. (20)

2. Diagram the carbon cycle, label all the fluxes, indicate oxic and anoxic portions of the cycle. (20)

3. Diagram the nitrogen cycle, label all the fluxes, indicate oxic and anoxic portions of the cycle. (20)

4. Give examples from the book of each type of the following interactions, where at least one of the organisms is a microbe: commensalism, synergism (mutualism), predation, competition. (8)

5. Discuss how the iron, sulfur and phosphorus cycles are linked considering both anoxic and oxic habitats. (7)

6. Discuss how viruses alter flux of organic materials in microbial systems, and some of the factors that may control rates of viral infection of microorganisms. (10)

7. Discuss the intermediate disturbance hypothesis and microbial systems (Mendy does not have to relate this to cactus tissue injury experiments). (10)

8. Describe briefly 3 modes of bacterial predation and possible defense against each. (5)

9. If Monod uptake rates are known for inorganic nitrogen, and the Redfield ratio of the microbial communities is 106:16:1, how much lower would you expect the half saturation constant for growth using phosphate to be than for growth using inorganic nitrogen? (5 points extra credit)

Have a good vacation!