Which of the following limits the number of trophic levels in a food chain ?

Which of the following represent the food chain in a forest?

_____ are present in the first trophic level in the food chain.

Energy and nutrients flow from one trophic level to another in an ecosystem. Which one of the following statements correctly describes the direction of flow of energy and nutrients in an ecosystem?

Which of the following are constituents of an ecosystem?

Which one of the following is not a gaseous biogeochemical cycle in ecosystem?