1. Explain the importance of autotrophic organisms with respect to energy flow and nutrient cycling in ecosystems.
2. List and describe the importance of the four consumer levels found in an ecosystem.
3. Explain how gross primary productivity is allocated by the plants in an ecosystem.
4. List the factors that can limit productivity of an ecosystem.
5. Explain why productivity declines at each trophic level.
6. Distinguish between energy pyramids and biomass pyramids.
7. Describe the hydrologic (water) cycle.
8. Describe the carbon cycle, and explain why it is said to result from the reciprocal processes of photosynthesis and cellular respiration.
9. Describe the nitrogen cycle, and explain the importance of nitrogen fixation to all living organisms.
10. Explain how phosphorus is recycled locally in most ecosystems.
11. Explain why the soil in tropical forests contains lower levels of nutrients than soil in temperate forests.
12. Describe how agricultural practices can interfere with nitrogen cycling.
13. Describe how deforestation can affect nutrient cycling within an ecosystem.
14. Describe how the carbon cycle differs in terrestrial and aquatic systems.
15. Explain how "cultural eutrophication" can alter freshwater ecosystems.
16. Explain why toxic compounds usually have the greatest effect on top-level carnivores.
17. Describe how increased atmospheric concentrations of carbon dioxide could affect the Earth.
18. Describe how human interference might alter the biosphere.