Biomass is mass of living material. It decreases along a food chain.
Pyramids of Biomass
Plant Energy Loss
Only 10% of the sun's energy is used for growth in a plant. The rest is either reflected into the atmosphere, passed through the leaf or heats the leaf up.
Animal energy loss
Again., only 10% of energy from the plant or other animal is used for growth. The rest is lost in respiration, in waste products, in heat to the atmosphere, in movement, and when the animal dies.