UPSC Prelims 1997 · General Studies

Question 120: Environment and Ecology

Which one of the following organisms is likely to show the highest concentration of DDT once it has been introduced into the ecosystem?

aGrasshopper

bToad

cSnake

dCattle

AnswerThe answer is (c).

DDT is not broken down in the body and builds up in fat, so it becomes more concentrated at each step up a food chain (biomagnification). In a chain such as grass, grasshopper, toad, snake, the top predator, the snake, carries the highest concentration. Cattle eat plants and stand low in the chain.

Why each option is right or wrong

(a) The grasshopper feeds on plants and sits low in the chain.
(b) The toad eats insects and carries less than the snake that eats it.
(c) Right: the snake is the top predator in the chain.
(d) Cattle are herbivores near the bottom of the chain.

Explanation: written by UPSC Grade, not by UPSC.

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Source: UPSC, Civil Services (Preliminary) Examination 1997, General Studies. UPSC's own paper isn't online; the words are from a published compilation. The paper on upsc.gov.in.