Question

Which of the following limits the number of trophic levels in a food chain?

• A. Decrease in energy at higher trophic levels
• B. Sufficient food supply
• C. Polluted air
• D. Water

Answer 1

The correct option is A

Decrease in energy at higher trophic levels

The correct option is A.

The explanation for the correct option:

1. When energy passes from one trophic level to the next one, only 10 percent of it will pass this is referred to as the 10% rule.
2. By the 10% rule, the energy available at a given trophic level is 10 times lesser than the energy present in the previous trophic level.
3. By reaching the fourth trophic level a few amounts of energy reach the producer.

The explanation for the incorrect options:

Option B

1. As one eats the other in the moving trophic levels of a food chain the supply of food is sufficient.
2. So, it cannot limit the number of trophic levels in a food chain.

Option C

1. Polluted air will not affect a particular trophic level rather it is the same for all in the food chain.
2. So polluted air will not restrict the number of trophic levels in a food chain.

Option D

1. Water supply can restrict the number of organisms at a trophic level.
2. But it cannot affect the number of trophic levels.

Final answer: A decrease in energy at a higher trophic level can limit the number of trophic levels in a food chain.