AP BIOLOGY

Detailed explanation-1: -Within all biological communities, energy at each trophic level is lost in the form of heat (as much as 80 to 90 percent), as organisms expend energy for metabolic processes such as staying warm and digesting food (see biosphere: The organism and the environment: Resources of the biosphere: The flow of energy).

Detailed explanation-2: -The amount of energy at each trophic level decreases as it moves through an ecosystem. As little as 10 percent of the energy at any trophic level is transferred to the next level; the rest is lost largely through metabolic processes as heat.

Detailed explanation-3: -On average, only about 10% of the energy stored as biomass in one trophic level-e.g., primary producers-gets stored as biomass in the next trophic level-e.g., primary consumers. Put another way, net productivity usually drops by a factor of ten from one trophic level to the next.

Detailed explanation-4: -Not all the energy is passed from one level of the food chain to the next. About 90 per cent of energy may be lost as heat (released during respiration), through movement, or in materials that the consumer does not digest. The energy stored in undigested materials can be transferred to decomposers.

Detailed explanation-5: -Heat Losses From Ecosystems:-Heat resulting from cell respiration makes living organisms warmer. This heat can be useful making cold-blooded animals more active. Birds and mammals increase their rate of heat generation if necessary to maintain their constant body temperatures.