BRAINCAKECommunity level systems
Revision notes for Community level systems in OCR Biology A (J247). Every lesson in BrainCake comes with R.E.C.I.P.E. recall steps, a quick check and spaced reviews.
- Materials cycling through an ecosystemLiving things take chemicals from their surroundings and later return them.
- The role of microorganisms in cycling materialsDead plants and animals, and waste such as faeces, contain carbon, nitrogen and other useful materials.
- The carbon cycle and the water cycleThe carbon cycle moves carbon between the air, living things and dead material.
- Factors affecting the rate of decompositionDecomposers are living organisms, so their rate of decomposition depends on the conditions around them.
- Levels of organisation in an ecosystemEcologists describe living things at different levels of organisation, from a single organism up to a whole ecosystem.
- How abiotic and biotic factors affect communitiesThe make-up of a community depends on abiotic factors (non-living) and biotic factors (living).
- Interdependence and competitionOrganisms in a community depend on each other.
- Trophic levelsA trophic level is a feeding position in a food chain.
- Pyramids of biomass and biomass lossA pyramid of biomass shows the mass of living material, called biomass, at each trophic level in a food chain.
- Efficiency of biomass transferThe efficiency of biomass transfer tells us what percentage of the biomass at one trophic level ends up in the next level.