We know that among the physiological processes of organisms, excretion is one of them. The animal excrete the nitrogenous waste products from the body through excretion. In this decomposition process some energy is spent. Besides this, the living organisms lose energy due to other physiological process. Living organisms come to an end through death and lose energy. This energy is called lost energy. The decomposers get necessary energy from the dead bodies and excretory products of different trophic level. In this way energy is transferred and the food chain remains effective. Some examples of food chains are given below with which a human being is related in some way and they are the last level of the chain. It is seen that some of these food chains are very small and others are very large.
As for example
Living organisms spend a lot of energy in respiration and other biological functions. If the food chain is short, less energy is spent and if it is long then more energy is spent. From this rule it is understood that more the energy is transferred from producers to higher levels less the energy remains.