B1.5:Energy and Biomass in Food Chains

A food chain shows what eats what. The first organism is called a producers (i.e. a plant). The animal that eats the plant is called a primary consumer (prey) followed by a secondary consumer (predator).

TROPHIC LEVEL - each stage of a food chain

There is less energy and less biomass every time you move up a trophic level in a food chain.

BIOMASS - the mass of living material

Each bar on a pyramid of biomass shows the mass of living material on the food chain (how much all the organisms at each level would 'weigh' if you put them all together). The big bar at the bottom of the pyramid represents the producer, the next bar will be the primary consumer, then the secondary consumer etc.

Energy from the sun is the source of energy for nearly all life on earth. Plants use the light energy from the sun and convert it into chemical energy during photosynthesis. The energy stored in the plants passes through the food chain as animals eat them and each other.

Biomass and energy is lost at each stage of the food stage because of:

Respiration - every organism in the food chain respires. Most of the energy released by respiration is eventually lost to the surroundings as heat.

Uneaten material - some of the plant and animal material is inedible (e.g. bone), so it doesn't pass on to the next stage of the food chain Also, some organisms die before they're eaten, so their remains are left to decay and their energy doesn't get passed along the food chain.

Waste products - material and energy are lost from the food chain in the organisms waste materials (e.g. poo and urine), which are not eaten.