Q.How is the local bird population affected by the use of DDT in crops by the farmers?

Biomagnification means pollutant concentration increases at each successive trophic level, peaking at the top consumer.

Brominated Flame Retardants (BFRs), like other persistent, non-biodegradable pollutants (e.g. DDT, heavy metals), undergo biological magnification as they pass along a food chain. Each organism absorbs the pollutant from its food/environment but cannot easily excrete or break it down, so the pollutant accumulates in its tissues. Because a large number of organisms at a lower trophic level are consumed by fewer organisms at the next level, the pollutant's concentration increases at every step: Phytoplankton -> Zooplankton -> Herr …

DDT and mercury both biomagnify, so the answer is (C).

Biomagnification (biological magnification) is the increase in concentration of a persistent, non-biodegradable toxicant at successive trophic levels of a food chain. Because these substances are not excreted or broken down, they accumulate in body fat and become more concentrated in top predators. Classic examples are DDT (an organochlorine pesticide) and mercury (a heavy metal) — both biomagnify, harming top consumers (e.g …

Biomagnification occurs specifically with substances that are fat-soluble and non-biodegradable, so they accumulate in an organism's tissues rather than being broken down or excreted, and their concentration keeps rising as they pass up through successive trophic levels — mercury and the pesticide DDT are the textbook examples.

Reasoning

Biomagnification refers to the phenomenon in which the concentration of certain toxic, non-biodegradable substances progressively increases as they pass from one trophic level to the next in a food chain, because the substance accumulates in body tissue faster than it can be metabolised or excreted. This requires the pollutant to be (i) non-biodegradable and (ii) fat-soluble, so it persists and concentrates in living tissue. Classic examples include the pesticide DDT (a chlorinated hydrocarbon that famously biomagnified up aquatic food chains, causing eggshell …

Biomagnification causes toxic, non-degradable pollutants to build up to dangerous levels as they pass up a food chain, with top predators accumulating the most.

Biomagnification describes the increase in concentration of certain harmful, non-biodegradable chemical substances (such as the pesticide DDT or heavy metals like mercury) as they pass from one trophic level to the next in a food chain. Because these substances are not readily broken down or excreted by organisms, they accumulate in an organism's tissues (bioaccumulation) and get passed on, in increasingly concentrated form, when that organism is eaten by the next consumer up the chain — since each predator must eat many prey to survive, the toxin concentration keeps rising at each step. This is why top carnivores (e.g., birds of prey in the classic DDT example, where thin, easily-broken eggshells resulted from DDT biomagnif …

Biomagnification is the progressive increase in the concentration of a persistent toxic substance as it passes up through trophic levels of a food chain.

Consider the classic example of DDT in an aquatic food chain: phytoplankton absorb DDT from water at a low concentration (say 0.003 ppm); zooplankton that feed on the phytoplankton accumulate it at a higher concentration (0.04 ppm); small fish eating the zooplankton concentrate it further (0.5 ppm); and fish-eating birds at the top of the chain end up with the highest concentration (up to 25 ppm), because DDT is fat-soluble and not readily excreted — so it accumulates in the body and is passed on, undiminished, when the organism is eaten. This is biomagnification.

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