Assume there are 50,000 joules (J) of energy available in trophic level II in the figure. According to the conventional model of energy flow in ecosystems, which of the following statements correctly describes the flow of energy in the system?

Approximately 10% of the energy is retained when moving up levels in a trophic pyramid. The other 90% is used to do work or is lost as heat.

If there are 50,000 joules in level II, there will be 5,000 in level III, and 500 in level IV. Level I will need to produce 500,000 joules to sustain the pyramid.