Question

Pollution caused by persistent pesticides is relatively more hazardous to which type of organism?

• A. Herbivores
• B. First level canivores
• C. Producers
• D. Top carnivores

Answer 1

The correct option is D Top carnivores

Pollution caused by persistent pesticides is relatively more hazardous to top carnivores. It happens because of biomagnification. It is phenomenon through which certain pollutants get accumulated in tissues in increasing concentrations along the food chain. Such pollutants (e.g. DDT and mercury) are non-biodegradable, i.e., once they are absorbed by an organism, they cannot be metabolised and broken down or excreted out. These pollutants generally get accumulated in fat containing tissues of the organism.

For example, in an aquatic food chain, the concentration of DDT is increased at successive tropic levels; say it starts at 0.003 ppb (parts per billion) in water, it can ultimately reach 25 ppm (parts per million) in fish-eating birds which are the top carnivores through biomagnification. High concentrations of DDT disturb calcium metabolism in birds, which causes thinning of egg shell and their premature breaking, eventually causes decline in bird populations.