Biology B1 (Food chains, energy, biomass and cycles)


Food chains show the feeding relationships between living things: for example, grass seed is eaten by a vole, which is eaten by a barn owl.

Food chains

A food chain shows what eats what in a particular habitat. Pyramids of biomass reveal the mass of living material at each stage in a chain. The amount of material and energy decreases from one stage to the next. The arrows between each item in a food chain always point in the direction of energy flow - in other words, from the food to the feeder.

WordMeaning producers green plants and algae

they make food by photosynthesis

primary consumers usually eat plant material - they are herbivores

for example rabbits, caterpillars, cows and sheep

secondary consumers usually eat animal material - they are carnivores

for example cats, dogs and lions

predators kill for food

they are either secondary or tertiary consumers

prey the animals that predators feed on scavengers feed on dead animals

for example, crows, vultures and hyenas are scavengers


feed on dead and decaying organisms, and on the undigested parts of plant and animal matter in faeces

Energy is transferred along food chains from one stage to the next but not all of the energy available to organisms at one stage can be absorbed by organisms at the next one. The amount of available energy decreases from one stage to the next.

Some of the available energy goes into growth and the production of offspring. This energy becomes available to the next stage, but most of the available energy is used up in other ways. For example:

  • energy released by respiration is used for movement and other life processes, and is eventually lost as heat to the surroundings
  • energy is lost in waste materials, such as faeces.

All of the energy used in these ways returns to the environment, and is not available to the next stage.

Pyramids of biomass

Biomass means the…


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