The increase in concentration of harmful chemical substances (pesticides) in the body of living organisms at each trophic level of a food chain is called biological magnification.
The concentration of harmful chemicals will be different at different trophic level, because the animals at the highest trophic level or at the extreme right side of the food chain will have the maximum concentration of harmful chemicals in the body, and grass which is at the lowest trophic level will have minimum concentration of harmful chemicals.
