Question

16/23
why do ecosystems rarely contain more than a few trophic levels?
energy cannot flow through levels.
energy transfer efficiency is high (90%).
energy transfer efficiency is low (10%).
energy amounts are constant.

Explanation:

To determine the answer, we analyze each option:

• "Energy cannot flow through levels" is incorrect as energy does flow between trophic levels.
• "Energy transfer efficiency is high (90%)" is wrong; energy transfer between trophic levels is typically about 10% efficient (low efficiency), not 90%.
• "Energy transfer efficiency is low (10%)" is correct. As energy moves up trophic levels, only ~10% is transferred to the next level. After a few levels, the remaining energy is too little to support another level.
• "Energy amounts are constant" is incorrect because energy decreases as it moves through trophic levels (due to energy loss as heat, for maintenance, etc.).

Answer:

C. Energy transfer efficiency is low (10%).