Question

Why the last organism of the food chain have the maximum concentration in biological magnification?

Answer 1

The increase in the concentration of pollutants or harmful chemicals with each step of the food chain is called biomagnification.
The chemicals (pesticides and other chemicals) enter the food chain due to rains that carry these chemicals into the aquatic plants and animals. The land plants absorb these chemical along with the water and minerals from the soil.
These chemicals cannot decompose; thus, they accumulate continuously at each trophic level. As the food chain proceeds, concentrations of the pesticides also increase. Thus, their maximum concentration is among the top carnivores. Hence, the last organism of the food chain have the maximum concentration in biological magnification.