Answer:
The phenomenon through which certain pollutants (harmful chemicals) get accumulated in tissues of organisms at different trophic levels in increasing concentrations along the food chain, is called Biomagnification.
Explanation:
1)Suppose, DDT is being used in a farmland.
2)There's a water body nearby the farmland and the water is contaminated with the DDT(let's say the quantity: 0.003 ppb).
3)Now the aquatic organisms (Zooplankton) which consume this water also consuming the DDT also.(0.04 ppm)
4)Next these Zooplanktons are consumed by small fishes. (0.5 ppm)
5)These small fishes are then consumed by Large fishes. (2 ppm)
6)These Large Fishes are consumed by Humans or Birds afterwards. (25 ppm)
7) So at each step DDT is also getting accumulated and at each successive trophic level the quantity of Accumulated DDT gets magnified as the organisms on higher trophic levels consume more biomass than the previous ones. This is a classical example of Biomagnification.
The gene pool of the population will remain relatively constant.
