Question

What is meant by biological magnification? With the help of a food chain, explain how biological magnification of harmful chemicals can occur.

Answer 1

The increase in the concentration of harmful substances, such as pesticides, in the body of living organisms at each level of a food chain is called biological magnification.
Chemical substances such as pesticides are sprayed over crop plants to protect them from pests and diseases. When herbivorous animals eat plant food, these poisonous chemical pesticides go into their bodies. Man, being an omnivore, eats plant food as well as the meat of herbivores. Thus, the pesticides present in plant food and herbivores get transferred to man's body through food. Pesticides are non-biodegradable chemicals, so they get accumulated at each trophic level. Since humans occupy the top level in any food chain, the maximum amount of harmful chemical pesticides gets accumulated in our bodies, damaging our health gradually.
The following food chain explains how biological magnification of harmful chemicals can occur. Plants $\to$ Herbivore $\to$ Man