Question

If the energy available at the producer level is 1000 J, then how much energy is available at the fourth trophic level?

• A. 100 J
• B. 10 J
• C. 1 J
• D. 10,000 J

Answer 1

The correct option is C 1 J

Energy flow in the ecosystem is the flow of energy from the sun through the successive trophic levels.

The trophic levels in an ecosystem denote the different levels in a food chain, based on the food source of an organism.

As organisms of one trophic level feed on other organisms of a lower trophic level, the energy flows through the ecosystem.


The 10 percent law states that only 10 % of energy is passed on from one trophic level to the next.

In the given scenario, the energy available at the producer level (first trophic level) = 1000 J

As per 10 percent law, the energy available at the level of primary consumers (second trophic level) = (10/100) X 1000 J = 100 J

The energy available at the level of secondary consumers (third trophic level) = (10/100) X 100 J = 10 J

The energy available at the level of tertiary consumers (fourth trophic level) = (10/100) X 10 J = 1 J

Hence, the amount of energy available at the fourth trophic level is 1 J