Explain the energy flow in a food chain.

▪       Energy enters most communities as light, where it is absorbed by autotrophs (e.g. plants) and converted into chemical energy via photosynthesis

▪       Energy then gets passed to the primary consumer (herbivore) when they eat the plant, and then gets passed to successive consumers (carnivores) as they are eaten in turn

▪       Energy is lost between trophic levels in the form of heat through cell respiration, faeces, tissue loss and death.

▪       Some of this lost energy is used by detritivores and saprotrophs. These in turn also lose energy in the form of heat through cell respiration. 

 

à Only ~10% of energy is passed from one trophic level to the next, the rest is lost.  

Because ~90% of energy is lost between trophic levels, the number of trophic levels are limited as energy flow is reduced at higher levels