Given a scientific question and its correct answer, generate supporting facts for the answer. This supporting fact can be an explanation for the answer to the given question.

Question: Which cycle tracks the flow of nitrogen through an ecosystem? Answer: nitrogen cycle
Mariana Ruiz Villarreal (LadyofHats) for CK-12 Foundation. The nitrogen cycle tracks the flow of nitrogen through an ecosystem . CC BY-NC 3.0.

Question: Green cyanobacteria on a lake produce food through what process? Answer: photosynthesis
Green cyanobacteria on a lake make food by photosynthesis.

Question: What is a close relationship between two species in which at least one species benefits? Answer: symbiosis
Symbiosis is a close relationship between two species in which at least one species benefits.