1. Why aren't all the leaves of trees, grass, and bushes eaten away by herbivores? 2. What effect does the amount of producers have on the number of consumers higher in the food chain?

3. What effect can top predators such as sea otters or killer whales have on producer populations? (Describe the concept of a trophic cascade)

4. How did researchers determine how healthy different foods were for humans to eat?

5. Based on the rule of 10 percent, describe why eating a plant-based diet is more efficient than a meat-based diet.