AP Environmental Science

Answer: B - Parasites feed at all of the trophic levels in a food chain.

Key Takeaway: Parasites are a unique part of the food chain. Usually, they are left out of the primary description of trophic levels in the food chain (producer, primary consumer, secondary consumer, tertiary consumer, and decomposers); though when they are included, they are usually at the very top of the chain. This is because parasites can function at every trophic level, can reproduce extremely quickly, and they always benefit at the expense of the host. In many cases, the host can be killed by the parasite, no matter how small the parasite may be.