Question

Assertion : The pyramid of biomass indicates the decrease in biomass at each trophic level from base to apex.
Reason : Parasites have inverted pyramids for biomass.
A. Both Assertion and Reason are correct but Reason is the correct explanation for Assertion.
B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion.
C. Assertion is correct but Reason is incorrect.
D. Both Assertion and Reason are incorrect.

Answer 1

Hint: An ecological pyramid represents the ecological parameters of different trophic levels graphically in per unit area of an ecosystem. Parameters like the number of organisms, energy, biomass, etc. are studied using ecological pyramids.

Complete answer:
An ecological pyramid is a graphical representation that reflects the relationship between biomass, productivity, or energy at different trophic levels. The ecological pyramids always begin with producers which are present at the bottom and end with the apex predators present at the top level. Generally, there are three types of ecological pyramids observed which are the pyramid of biomass, the pyramid of energy, and the pyramid of numbers. The pyramid of energy explains the rate of energy flow and productivity at different consecutive trophic levels. The pyramid of energy is always upright. In the pyramid of numbers, it represents the number of individual organisms at different consecutive trophic levels per unit area of an ecosystem. This pyramid shows the numbers of producers, herbivores, carnivores, and decomposers. The pyramid of biomass represents the total biomass generated and transferred at different consecutive trophic levels per unit area of an ecosystem. The pyramid of biomass is always upright according to the amount of biomass. In the upright pyramid of biomass, the amount of biomass is decreasing or there is a gradual reduction in the biomass at the different trophic levels from base to apex. In some cases, such as the aquatic ecosystem it may be inverted or the reverse of the upright. Therefore, the assertion is true. In the case of parasites, the pyramid of biomass cannot be inverted. There is a chance to increase the number of parasites that may increase gradually i.e. the pyramid of numbers may be inverted. When a parasite is present in the body of the host, then the biomass of the parasite never be more than the host. Therefore, it can never be inverted. Hence the reason is not true.
Thus, the right option is C.

Note: An ecological pyramid is the representation of the various ecological parameters like the number of organisms, energy, biomass, etc. found at successive trophic levels. There are three types of the ecological pyramid: the pyramid of Biomass, the pyramid of energy, and the pyramid of numbers. The pyramid of biomass is always upright because the amount of biomass is gradually decreasing at each trophic level. In the case of the parasite, the pyramid of biomass is also upright.