Question

The concentration of DDT from lower to higher trophic level-
a. Increases
b. Decreases
c. Increases or decreases
d. Remains constant

Answer 1

Hint: Biomagnification is defined as an increase in the level of toxicity or accumulation of toxins with successively higher levels of the food chain. DDT is also known as Dichlorodiphenyltrichloroethane which is an organochlorinated compound that is stable. DDT is fat-soluble, which is stored in fatty tissues of animals.

Complete answer:
DDT (Dichlorodiphenyltrichloroethane) is an organic chlorinated compound that is stable. It is highly soluble in the fats of the living organism and so, it shows persistence in the food chain.

It is observed that the level of DDT increases as the food chain progresses. It means, the primary consumers will have more DDT concentration than the producers, the secondary consumers will have more than primary consumers, and so on.

The highest concentrations will be seen in the top carnivore. This is because the consumers at the successive trophic level consume more than the previous level to fulfill the energy requirements. Due to this, DDT keeps on accumulating in the successive trophic levels in higher concentrations. This process is called biomagnification.

Hence, The correct answer is option (A).

Additional information:
- DDT takes a relatively long amount of time to break down.
- If a predator consumes multiple organisms and each organism contains a small amount of DDT, the amount of DDT in the predator is going to be the result of all of those small amounts combined which are considered to be significantly higher than it should be.
- For instance, the concentration of DDT in large fish is 2ppm (parts per million) but the fish-eating bird has a concentration of 25ppm. So with the successive level in a food chain, the level of toxin keeps increasing.

Note: Bioaccumulation occurs within a trophic level. A food chain is a sequence of organisms in which there is a transfer of nutrients and energy when one organism eats another.
The trophic level is the position that an organism occupies in a food chain, food web. There are four types of trophic levels- Producers, Primary Consumers, Secondary consumers, and Tertiary consumers.