the Autotrophs absorb the energy of sunlight and covert into food energy
 .the consumers eat this and the large amount of energy is wasted in the form of heat to environment . in that it is used for digestion for work and the rest for growth and reproduction. the 10% of food eaten is for own body and next trophic level
.thus 10% is the average value of energy in each organic matter in each level for the each level of trophic
due to large amount of energy is loosed the food chain consists only 3 4 trophic level only little usable enregy is left after 4 trophic level
there are more individual in the bottom most level the producers are more
the length of organism are very large it vary each organism is eaten by 2 3 animal thus they are eaten by several others . therefore just representing in food chain they can represent in long chain food web

through the biological magnification the chemicals are absorbed by he plants and water bodies in water bodies by marine plants and animals this is how to enters our food chain  it progressively increaese in each level thus the human occupy the top most the maximum is absorbed by human