BRAINCAKEEnergy and Ecosystems
Revision notes for Energy and Ecosystems in AQA Biology (7402). Every lesson in BrainCake comes with R.E.C.I.P.E. recall steps, a quick check and spaced reviews.
- Producers, Consumers and DecomposersEvery ecosystem depends on a flow of energy through organisms, which can be grouped by how they obtain their energy.
- Trophic LevelsA trophic level is the position an organism occupies in a food chain, based on how it gets its energy. • Trophic level 1: producers • Trophic level…
- BiomassBiomass is the total mass of living material in a given area (or volume, for aquatic ecosystems) at a particular time.
- Measuring Biomass - Dry MassDry mass is the mass of an organism's tissue after all the water has been removed.
- Calorimetry and Chemical Energy in BiomassThe chemical energy stored in dry biomass can be estimated using calorimetry.
- Gross Primary ProductionGross primary production (GPP) is the chemical energy store in plant biomass, in a given area or volume.
- Net Primary ProductionNet primary production (NPP) is the chemical energy store in plant biomass after respiratory losses to the environment have been taken into account.
- NPP = GPP - RThe relationship between gross and net primary production is: NPP = GPP − R where NPP is net primary production, GPP is gross primary production and…
- Net Production of ConsumersConsumers also lose much of the chemical energy they take in.
- Efficiency of Energy TransferOnly a small proportion of the energy at one trophic level is transferred to the biomass of the next.
- Calculating Percentage EfficiencyThe efficiency of energy transfer between two trophic levels is calculated as: percentage efficiency = (energy transferred to the higher level /…
- Farming Practices and ProductivityPrimary productivity and secondary productivity are the rates of primary and secondary production.
- Reducing Respiratory Losses in LivestockIn a human food chain, much of the energy that livestock take in is used in respiration and lost as heat, rather than being stored as meat, milk or…
- Simplifying Food Webs to Reduce Energy LossIn a natural ecosystem, energy from producers flows into many food chains.
On the specification
- 3.5.3 Energy and ecosystems