Assertion (A): The number of trophic levels in a grazing food chain is generally restricted to three or four. Reason (R): Only about 10 per cent of the energy is transferred to each successive trophic level from the lower trophic level.

Step-by-step solution

According to the 10 per cent law proposed by Lindeman, only about 10 per cent of the energy is transferred from one trophic level to the next successive trophic level. The remaining energy is lost during respiration and other metabolic activities. Because of this significant loss of energy at each step, the amount of available energy decreases drastically at higher trophic levels. Consequently, there is not enough energy to support a large number of trophic levels, which restricts the grazing food chain to generall