CBSE Class 10 Science 2023 · Paper 31/6/2 · Question 33

The food chain is plants $\to$ rats $\to$ snakes $\to$ peacock, and the peacock is likely to have the highest concentration of the chemical because it is at the highest (fourth) trophic level. Harmful chemicals such as pesticides are not biodegradable: they enter the plants from the soil and water, are not broken down in the body and so are stored, and each consumer takes in the chemical from all the food it eats. The concentration therefore rises at every step and is highest in the peacock. The process is biological magnification: the progressive increase in the concentration of harmful non-biodegradable chemicals at successive trophic levels of a food chain.