GCSE Biology Unit 2 (9)

Pyramids of Number and Biomass

• A trophic level is a feeding level.
• Every time you move up a stage (trophic level) in a food chain, there's less energy and less biomass.
• There are also usually fewer organisms every time you move up a level too:
• For example, 100 Dandelions feed 10 rabbits which feed 1 fox.
• This is not always true though - for example, there are likely to be around 500 fleas feeding on the fox. The number has increased as you move up that stage.
• Therefore, a better way to look at a food chain is to think about biomass instead of number of organisms.
• You can use info about biomass…