NEET Questions Solved


With the help of a flow chart , show the phenomenon of biomagnification of DDT in an aquatic food chain.

Biomagnification is increase in concentration of the toxicant at successive trophic levels. Toxic substances cannot be metabolised or excreted , so they got accumulated in the body of an organism. Through food chain these substances are passed to the next trophic level. 

For example, DDT and mercury . The concentration of DDT is increased at successive trophic levels e.g., if there is DDT of about 0.003 ppb (parts per billion) in water, it can ultimately reach 25 ppm in fish-eating birds through biomagnification.

High concentration of DDT in birds interferes with calcium metabolism which causes thinning of egg shell and their premature breaking. This will result in decline in bird population.

Difficulty Level:

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