Question 6

In this model, food chains rarely contain more than four or five trophic levels. Which reason best explains that limit?

Producers stop growing once four levels feed on them
Predators at high levels prefer to eat producers directly
Too little energy remains after several transfers to support another levelCorrect answer
Decomposers remove the fifth level before it can form

Explanation

Because roughly ninety percent of the energy is lost at each step, the energy left after four or five steps is too small to support a further population. Decomposers do not set the length of the chain, because they act on dead material at every level rather than removing a level from it.

Explanation

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