KCET 2018 Biology Solved Paper

The accumulation of dicholorodiphenyl trichloroethane and polychlorinated biphenyls. The PCBs, industrial pollutants, discharged into water bodies in Great Lakes of USA increased from a concentration of 0.000002 ppm in water to 4.83 ppm in fishes and 124 ppm in predator birds. In the same way, DDT, a chemical pesticide, accumulated from 0.000003 ppm in water to 25 ppm in birds of prey. These chemicals are stored in the fat tissues of living organisms.