Detailed Instructions: Given a scientific passage and an answer, generate a question for the given answer.
Q: Passage: Describing the flow of energy within an ecosystem essentially answers this question. To survive, one must eat. Why? To get energy. Food chains and webs describe the transfer of energy within an ecosystem, from one organism to another. In other words, they show who eats whom. Answer: food webs
A:
Food chains and what describe the transfer of energy within an ecosystem, from one organism to another?