1. Why do O₂ levels drop in saturated soil?

a. O₂ diffusion is much slower in water than in air.
b. Increased moisture levels increase microbial demand for O₂.
c. O₂ breaks down in water.
d. O₂ is converted to CO₂ in saturated soils.

2. When a plant dies in a well-drained upland area, it decomposes. What set of carbon transformations do the decomposing organisms carry out?

a. glycolysis, then fermentation, then the Krebs cycle
b. glycolysis, then the Krebs cycle, then fermentation
c. glycolysis, then the Krebs cycle, then electron transport
d. glycolysis and fermentation

3. When a plant dies in a poorly-drained wetland, it can still decompose, but in a different way. What set of carbon transformations do the decomposing organisms typically carry out here?

a. glycolysis, then fermentation, then the Krebs cycle
b. glycolysis, then the Krebs cycle, then fermentation
c. glycolysis, then the Krebs cycle, then electron transport
d. glycolysis and fermentation

4. Why is water retention not usually a problem in freshwater habitats?

a. Cells are normally hypertonic to such a habitat.
b. Cells are normally hypotonic to such a habitat.
c. There is no difference in water concentration between the inside and outside of a cell.
d. The permeability of cell membranes to water in freshwater habitats.

5. What is a mechanism that cells can use to avoid problems with excess Na⁺?

a. maintenance of high intracellular concentrations of K⁺
b. maintenance of high intracellular concentrations of Na⁺
c. excretion of K⁺ into the surrounding soil
d. oxidation of Na⁺ to Na²⁺

6. Ammonification can be defined as the conversion of

a. molecular nitrogen to ammonium.
b. ammonium to nitrate.
c. molecular nitrogen to nitrate.
d. organic nitrogen to atmospheric nitrogen.

7. Which process is involved in the "beaver cycle"?

a. Fe³⁺ reduction to Fe²⁺
b. ammonification
c. methanogenesis
d. aerobic respiration

8. If O₂ transport is sufficient, N can become more available to a plant by

a. reduction of NO₃^- to NH₄⁺ in the rhizosphere.
b. reduction of NH₄⁺ to NO₃^- in the rhizosphere.
c. oxidation of NH₄⁺ to NO₃^- in the rhizosphere.
d. oxidation of to NO₃^- to NH₄⁺ in the rhizosphere.

9. Which plant life history strategy would be least successful in a river swamp that floods at irregular intervals 1 to 3 times per year?

a. annual
b. biennial
c. perennial

Well, well now... (hee hee)... The answer to this is very arguable. (Gotcha thinking, didn't I?) My argument would be biennial. A biennial needs two consecutive years to complete its life cycle. How often can such a plant depend on two consecutive years of dry conditions during the growing season?

10. Early concepts of succession included which of the following?

a. Xerarch succession involves a site becoming drier over time.
b. Hydrarch succession involves a site becoming wetter over time.
c. Disturbances vary across different spatial and temporal scales.
d. Community changes are linear, unidirectional, and result in a "climax".