Question 2 - Past Year - 3 Mark Questions - Chapter 15 Class 10 - Our Environment

(a) State with reason the consequence of decrease in number of carnivores in an ecosystem.

(b) In a food chain, state the trophic level at which the concentration of harmful chemicals is maximum. Why is it so?

Answer:

(a)

• If there is a decrease in the number of carnivores in an ecosystem, this would lead to an increase in the number of herbivores. 
• The herbivores would eat as much plant species as possible and this would lead to a decrease in the number of plant species.
• This would lead to an imbalance in the ecosystem.

(b)

The increase in concentration of harmful and toxic substances in higher trophic levels in the food chain, due to the presence of these substances in the lower levels is called biological magnification.

The level of biomagnification would increase with increase in trophic level.

Therefore, the concentration of harmful chemicals is maximum at the highest trophic level.