Question

In the following food chain who gets more energy than the tertiary consumer and less than the primary consumer?
Grass → Grasshopper → Frog → Snake → Eagle
A. Grasshopper
B. Frog
C. Snake
D. Eagle

Answer 1

A food chain is a unilateral flow of energy from the producer to the final consumer. The energy flowing follows the 10 percent law, where only some of the energy is passed on from one organism to another.

Complete answer: A food chain, as the name suggests is a chain of organisms each occupying a specific trophic level. The main idea of the food chain is to identify how the energy is passed on from one trophic level to the other. It is generally a base rule that the energy flow in a food chain is always unilateral, as a frog cannot eat a snake, nor could a grasshopper eat a frog. According to multiple ecological studies, a widely accepted law would be the 10 percent law. The law states that only 10 percent of energy is obtained by each organism within the chain from consuming the previous organism. Whereas, energy is lost or dissipated in the transfer of energy from one trophic level to the other. In the given example, let us assume the plant (grass) obtains its energy from the sun through photosynthesis, if the energy of the sunray falling on the grass is 100,000 Joules, only 10,000 joules are transferred to the grass. Now, if the grasshopper eats the grass, only 1000 Joules is obtained by the grasshopper, whereas 9,000 joules is lost. Thus, in case of the frog, it is only 100 Joules and for the snake, 10 Joules, and the eagle 1 Joule is being transferred. In this case, the grass is the producer, the grasshopper is the primary consumer, the frog is the secondary consumer, and both the snake and the eagle are tertiary consumers.
Thus, the correct answer is option B.

Note: The snake and eagle are considered tertiary consumers as both the eagle and the snake could consume the frog, and both belong to the same trophic level. Food chains are simplified and do not provide a clear picture of ecological succession, as the consumer does not exclusively rely on only one organism for its food source. A much better understanding can be obtained by considering a food web, where energy flow is multidirectional and is much more accurate considering the reality.