1. Why is the efficiency of energy transfer between two trophic levels generally quite low?

2. How do ecologists distinguish between gross primary productivity and net primary productivity?

3. Compare and contrast the measurement of primary productivity in terrestrial versus aquatic ecosystems.

4. What factors limit the net primary productivity of terrestrial ecosystems?

5. What factors limit the net primary productivity of aquatic ecosystems?

6. Why might assimilation efficiencies be much higher for herbivores eating seeds than for herbivores eating leaves?

7. Why do aquatic and terrestrial ecosystems differ in their pyramids of biomass?

8. How do changes in stoichiometry affect assimilation efficiencies?

9. Why are residence times much longer in forest ecosystems than in aquatic phytoplankton-based ecosystems?

10. How might the carrying capacity for humans on Earth change if the human population ate more plant products than animal products?