CBSE Class 10 Answered

The various levels or steps in a food chain are called trophic levels. They represent the successive stages of nourishment like primary producer, primary consumer, secondary consumer, tertiary consumer etc. The autotrophs are at the first trophic level.

Only 10% of the energy gets transferred from one trophic level to the next. So after 3 or 4 trophic levels, the energy available for passing on is too less to support another trophic level. Very little usable energy remains after 4 trophic levels. Hence the number of trophic levels in afood chain is limited.