The amount of energy transferred from one trophic level to another in an ecosystem:

1. A

   Increases

   (a) Increases. Energy cannot grow from prey to predator as a rule; most is lost as heat.

2. B

   Decreases

   (b) Decreases. Only about 10 percent of energy is transferred to the next trophic level (Lindeman); the rest is lost in respiration and incomplete consumption. (b) Official key.

3. C

   Remains constant

   (c) Remains constant. That would violate the second law in ecological pyramids of energy.

4. D

   May increase or decrease

   (d) May increase or decrease. Energy pyramids are upright; the keyed quantity falls at each step.

Summary. Official key is (b). Energy transferred between trophic levels decreases (roughly the 10 percent law). It does not rise or stay constant.