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In the Silver Springs ecosystem, roughly what fraction of the energy passed from the producers to the primary consumers?
AAbout 48.1 percent of it
BAbout 81.4 percent of it
CAbout 1.48 percent of it
DAbout 14.8 percent of it
Answer & Solution
Correct answer: D. About 14.8 percent of it
1. Trophic level transfer efficiency is production at one level divided by production at the level below.
2. That ratio is then multiplied by 100 to give a percentage.
3. For Silver Springs the value between the first two levels is about 14.8 percent.
4. So roughly one seventh of the producers' output reached the primary consumers.
5. The rest was lost, largely as metabolic heat, as the second law of thermodynamics requires.
6. This low efficiency is the main reason food chains rarely run past four to six transfers.
7. Reading it as 48.1 or 81.4 percent would leave enough energy for far longer chains than any observed.
8. Reading it as 1.48 percent would make even a three level chain hard to sustain.
_Source: OpenStax Biology 1e (CC BY 4.0), Chs 44 and 46, section 46.2 Energy Flow through Ecosystems_
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