AP BIOLOGY

Detailed explanation-1: -Primary producers comprise the bottom trophic level, followed by primary consumers (herbivores), then secondary consumers (carnivores feeding on herbivores), and so on. When we talk of moving “up” the food chain, we are speaking figuratively and mean that we move from plants to herbivores to carnivores.

Detailed explanation-2: -A food web starts at trophic level 1 with primary producers such as plants, can move to herbivores at level 2, carnivores at level 3 or higher, and typically finish with apex predators at level 4 or 5.

Detailed explanation-3: -The energy passes from primary producers to primary consumers. From the primary consumers, the energy is passed to secondary consumers and then to tertiary consumers. Thus the energy pyramid is always upright.

Detailed explanation-4: -It follows that the carnivores (secondary consumers) that feed on herbivores and detritivores and those that eat other carnivores (tertiary consumers) have the lowest amount of energy available to them.

Detailed explanation-5: -Primary producers use energy from the sun to produce their own food in the form of glucose, and then primary producers are eaten by primary consumers who are in turn eaten by secondary consumers, and so on, so that energy flows from one trophic level, or level of the food chain, to the next.