1. Give a definition of life. Briefly discuss its utility with regard to viruses, obligate parasites, and mules (sterile offspring of donkey and horse). (10)

2. Describe one benefit of sexual reproduction in microorganisms not related to recombination of genes. (5)

3. Name 5 early microbiologists or ecologists and briefly describe their contributions. (10)

4. The surface area of a cylinder is A=2prh and volume V=p r² h , where r=radius and h=height. If you double the radius of the cylindrical cell, how many times greater is the volume? How many times greater is the surface area? How much does the surface area to volume ratio change? If the height of the cylinder is doubled, what happens to A, V and the A:V ratio? (5)

5. One strategy for planktonic diatoms to escape predation is to increase size. However, there are tradeoffs in increasing size related to staying in adequate light for photosynthesis, and maintaining inward rate of diffusion of nutrients. How might a cylindrical cell increase size and minimize any of the adverse effects that may be associated with this increase in size? Make sure your answer relates to Reynolds number and to the calculations you did in question 4. (10)

6. Explain the concept of redox, why it is difficult to predict exactly in the natural environment, even if some of the chemical composition is known, and why chemoautotrophs are constrained by the redox of their substrate (chemical energy source) and the redox of the medium in which they live. (10)

7. Suggest one habitat each that may be analogous to laboratory batch cultures and chemostats, respectively. Discuss how variations in conditions in these habitats may constrain the rate the cells are growing and what stage they are in. (10)

8. Draw a graph for photosynthesis versus irradiance, label both axes and the important points on the graph. (10)

9. As aquatic sediments get finer, some organisms become less common. Given the groups: bacteria, copepods, cladocerans (i.e. Daphnia), rotifers, ciliate protozoa, and ameboid protozoa, state the order in which you would expect these organisms to become less common and briefly explain why. (5)

10. Draw and label the major body parts of a rotifer. (5)

11. List and explain briefly three of the important physical factors that can influence microbial communities (biomass or production) in each of the following habitats (factors can be the same or different between habitats): atmo-ecosphere, lakes, estuaries, open ocean, soils. (15)

12. Give the equation for photosynthesis and respiration. (5)