Basically biomass is defined as the total biological material in a organism. It usually shortens the food chain because it is lost. Biomass is lost because not every part of an organism's body is able to be fully digested by another organism or is used up. Example- A lion eats a rabbit which ate grass few hours before. The rabbit already used up some energy through movement, respiration(grass turned to energy after digestion) and removal of faeces and urine(biomass). Furthermore, thelion cannot digest the bones of the rabbit so biomass is lost.