Why do persistent chlorinated hydrocarbon pesticides like DDT exhibit dangerous biomagnification at the top trophic levels of aquatic food chains?
Answer and explanation
Correct answer: B. they are fat-soluble, non-biodegradable, and concentrate progressively at each successive trophic step
- Step 1: DDT is fat-soluble and resistant to biological degradation. Step 2. Because organisms cannot excrete it, DDT accumulates in lipid tissues (bioaccumulation). Step 3. When predators consume large numbers of contaminated prey, pesticide concentration increases at each trophic level (biomagnification), reaching lethal levels in apex predators (e.g. fish-eating eagles). Answer: they are fat-soluble, non-biodegradable, and concentrate progressively at each successive trophic step. Why not the others: DDT is not water-soluble, not biodegradable, and does not evaporate harmlessly.
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