Final answer:
It is false that the skunk population can get only 15,000 joules of energy from the grass with 1,000,000 joules; they can get up to 100,000 joules based on the 10 percent energy transfer rule between trophic levels.
Step-by-step explanation:
The energy transfer between the trophic levels in an ecosystem is based on the ecological pyramid, which shows that, generally, only about 10 percent of the energy at one level is passed to the next level. The other 90 percent of the energy is used for metabolism, growth, repair, and lost as heat. If the grass has 1,000,000 joules of energy available, then according to this rule, primary consumers like a skunk would only benefit from a maximum of 100,000 joules of that energy. Therefore, it is false that skunks can get 15,000 joules of energy, as they can potentially get more based on this 10 percent energy transfer estimation.