Question

Increase in the concentration of the toxicant at successive trophic levels is known as
A. Biogeochemical cycling
B. Biomagnification
C. Biodeterioration
D. Biotransformation

Answer 1

Hint: It occurs due to the accumulation of toxic substances in an organism that cannot be metabolised or be excreted, and is therefore passed on to the next higher trophic level. This phenomenon is well known for the mercury and for the DDT.

Complete step by step answer: Biomagnification refers to an increase in the concentration of toxins at successive trophic levels of the food chain, such as the pesticide DDT, has reached in organisms higher up the food chain, generally through a series of prey-predator relationships. The substance becomes more concentrated in tissues or internal organs as they move up the chain. This increase can occur as a result of:
i. Persistence: where the substance cannot be broken down by environmental processes.
ii. Food chain energetics: where the substance's concentration increases progressively as it moves up a food chain.
iii. Low or non-existent rate of internal degradation or excretion of the substance: mainly due to water-insolubility.
It involves substances such as pesticides, heavy metals that make their way into lakes, rivers and oceans, and then move up to different levels of the food chain progressively as they are incorporated into the diet of aquatic organisms such as zooplankton.
Therefore, the correct answer is option B.

Note: Biomagnification is harmful because many living things die due to an increased level of toxicity. Some of the biomagnified chemicals are elements such as the selenium, mercury, nickel, or organic derivatives such as the methylmercury. Others are in the class of chemicals known as the chlorinated hydrocarbons.