Question

Which of the following statements is related to biological magnification?
a. There is a progressive increase in biological activities through trophic levels
b. There is a progressive increase in the level of harmful substances through trophic levels
c. There is a progressive increase in the body weight through trophic levels
d. There is a progressive increase in the number of organisms through trophic level

Answer 1

Biomagnification is also known by other names which are bioamplification or biological magnification. It is basically defined as the amount of concentration of a toxin in the tissues of organisms in a food chain. The increased amount of concentration of toxins can occur due to various reasons.

Complete answer:
Biological magnification is basically the toxins in the food chain. There are various trophic levels of an ecosystem which are interconnected with each other and they are very much essential for the survival of each other.
It is a kind of process in which pollutants such as pesticides and heavy metals come in contact with the food chain and then transfer to rivers or lakes where they are eaten up by various aquatic organisms such as fishes, frogs and these are eaten by large birds, animals or humans.
These all things happen because of increase in the concentration of substances, such as DDT or mercury in any organism.
So if we talk about the first option, there is no increase in biological activities through trophic level. Hence, this is an incorrect option.
Second option says accumulation of harmful substances through trophic level. So this is a correct option.
Third option says increase in body weight which is again incorrect.
And at last there is no increase in the number of organisms, so this is also incorrect.

Therefore, the correct answer is option (b).

Note:
The length of the food chain is variable and it gives the passage of energy as an index of ecological structures that increases through various linkages from the lowest to the highest trophic levels. The accumulated harmful substances are very slowly metabolized and also excreted very slowly.