Question

Two food chains are shown

(i) Tree ➡aphid ➡ insectivorous bird ➡prey feed on bird

(ii) Phytoplankton ➡ zooplankton ➡ plankton feeding fish ➡ carnivorous fish

Which diagram is a pyramid of energy representing both food chains?

A.

B.

C.

D.

Answer 1

Hint: Food chains have different trophic levels with different organisms residing on each level. Depending on the feeding habits the organisms are placed on each level. The lowest level comprises autotrophs while the uppermost level has scavengers like vultures or decomposers.

Complete step by step solution:
The autotrophs make their own food while consumers feed on those autotrophs. Energy is passed on from one trophic level to another as the organisms feed on each other. The law of energy distribution in a food chain in ecology states that only 10% of the total energy in the previous level gets transferred to the next level. This distribution of energy paves the path for construction of the pyramid of energy.

The pyramid of energy is known as ecological pyramid or trophic pyramid. It is the sequential representation of the total energy present in different trophic levels of the food web in the ecosystem. The energy present in each level shows the total amount of biomass generated by each organism in that level.

The lowest level has the most energy because of the producers as they make their own food and generate energy for themselves and for their consumers. The upper layers go on decreasing accordingly in a uniform manner.

Therefore, the diagram in option C is the correct option as it properly describes both the food chains.

Note: The representation of the food chain should be such that energy flow from one level to another decreases in ascending order. The uppermost level in the energy pyramid is the narrowest because it contains the least amount of energy and is already in the climax state.