EVERYDAY SCIENCE

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: -At each step up the food chain, only 10 percent of the energy is passed on to the next level, while approximately 90 percent of the energy is lost as heat.

Detailed explanation-3: -What happens to the other 90 percent of energy? It is used for metabolic processes or given off to the environment as heat. This loss of energy explains why there are rarely more than four trophic levels in a food chain or web.

Detailed explanation-4: -Only about 10% of the energy is transferred from one trophic level to another. The rest is used for life processes of the organism and some is lost as heat.

Detailed explanation-5: -With each trophic level, only 10% energy is transferred and 90% is lost as heat in respiration. If plants produce 1, 000kcal of energy, primary consumers will obtain 10/100 x 1000= 100 kcal of energy. Thus, the correct answer is C.