Question

Assertion(A): The pyramid of numbers in the pond ecosystem is upright.
Reason(R): Phytoplanktons are maximum and secondary consumers are lesser in number.

• A. If both A and R are true and R is the correct explanation of A
• B. If both A and R are true and R is not the correct explanation of A
• C. If A is true, but R is false
• D. A is false, but R is true

Answer 1

The correct option is A If both A and R are true and R is the correct explanation of A

Pyramids of numbers show the number of producers and consumers occupying the different trophic levels. Producers occupy the first trophic level, primary consumers occupy the second trophic level and secondary consumers occupy the third trophic level. The base of the pyramid represents the producers or the first trophic level while the apex represents tertiary or top consumers, which are the last trophic level.
The pyramid of numbers in the pond ecosystem is upright, because the base of the pyramid is occupied by the producers i.e. the phytoplanktons which are the highest in number in the pond. Then come the primary comsumers, followed by the secondary consumers. Hence, there is a gradual decrease in the number of individuals in the successive trophic levels.