Question

Biomagnification of DDT in aquatic food chain from 0.003ppb in water to fish-eating birds would be
A. 100ppm
B. 50ppm
C. 25 ppm
D. 2ppm

Answer 1

Biomagnification is a process by which the concentration of toxicant increases by a significant amount in each trophic level in the food chain. The toxins get accumulated at each level. The aquatic food chain consists of four levels consisting of the initial producers, primary consumers, secondary consumers, and tertiary consumers.

Complete answer:
The correct answer is an option ( C ) that is 25 ppm
The biomagnification of DDT in the aquatic food chain from 0.003ppb in water to fish-eating birds would be 25ppm.
Biomagnification is the process by which the concentration of toxic substances increases with each trophic level in the food chain. The accumulation happens because the substance cannot be metabolized or excreted. The most common example is the biomagnification of DDT in the aquatic food chain.
DDT is used to control mosquitos. So, it is generally sprayed on the plants near a water body. So, when the DDT seeps into the water, it gets incorporated into planktons which then act as primary producers in the aquatic food chain. The planktons are consumed by small fish (primary consumers). Since one small is going to eat several planktons, the concentration of toxicant increases. The small fish are eaten by large fish (secondary consumers) and eventually, aquatic birds (tertiary consumers) feed on these large fish.

So, from the initial DDT concentration of 0.003ppb, it can go up to 25ppm in aquatic birds.

Note:
DDT is harmful to animals and humans. The use of DDT in the fields has resulted in the thinning of the eggshells of birds that are part of the aquatic food chain. Humans also become prone to conditions like cancer, kidney diseases, liver problems, birth defects, etc. due to the biomagnification of certain toxicants in their food chain.