Question

In the given food chain, suppose the amount of energy at the fourth trophic level is 5 kJ, what will be the energy available at the producer level?

Grass → Grasshopper → Frog → Snake → Hawk

• A. 5 k J
• B. 50 k J
• C. 500 K J
• D. 5000 K J

Answer 1

The correct option is D

5000 K J

The correct answer is D.

Explanation of the correct option:

1. Overall, only about 10 percent of the energy stored as biomass in a trophic level is passed from one food level to the next. This is called “the 10 percent rule”.
2. The available energy level at a particular trophic level is 10 times greater at the next tropic level.
3. Hence, if the energy level at the fourth trophic level is 5 KJ, then the energy at a third level trophic level is 10 times greater than the previous level i.e. 5*10= 50 KJ.
4. The second trophic level has 500 KJ energy and the third trophic level (producer) has the energy of 5000 KJ.
5. There is a reduction of energy flow in an ecosystem along with the food chain and only 10 percent of the energy present at each trophic stage is carried onto the next trophic level.
6. Therefore, if 5000 KJ of energy is present initially, 500 KJ of energy will be possible at the next (or second) trophic level, 50 KJ of energy will be present at the next (or third) trophic level, and 5 KJ of energy will be possible at the next (or fourth) trophic level.

Final answer: 5000 KJ energy is available at the producer level.