Virginia 7th Grade Science SOL Practice Test

Energy moves through ecosystems in a one-way flow, and a lot of it is used up by the organisms at each step. As organisms go about living—breathing, moving, growing, reproducing—they burn energy and release much of it as heat. Only a small portion is stored as new biomass that the next trophic level can feed on. Because of this energy loss at every transfer, the amount available to the next level drops, so energy does not accumulate or double; it also doesn’t stay the same. That’s why most energy effectively leaves as heat and metabolic work, with only a fraction passing on to the next level.