GEOLOGY

Detailed explanation-1: -The concentration of DDT increases, as it moves or travels along the food chains. Its concentration is maximum in top trophic level. This process is called biomagnification.

Detailed explanation-2: -As Dichlorodiphenyltrichloroethane (DDT) moves up the trophic levels in food chains, or food webs, its concentration increases. This happens because DDT is fat soluble and so it accumulates in the bodies of organisms which come into contact with it.

Detailed explanation-3: -High concentrations of DDT disturb calcium metabolism in birds, which causes thinning of eggshell and their premature breaking, eventually causing decline in bird populations.

Detailed explanation-4: -Biomagnification happens when toxic chemicals, like DDT, whose remains in the environment are consumed indirectly by organisms through food. When an organism in the higher food chain consumes the lower organism containing such chemicals, the chemicals can get accumulated in the higher organism.

Detailed explanation-5: -DDT enters a food web at the lowest level, when small organisms like insects eat part of a plant infected with this toxic substance. The insect may die, or may survive, but in either case will eventually be eaten by a larger creature like a bird, who amasses more and more DDT with each meal.