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Led by Rachel Carson Simulacrum
The fourth module of the OCR GCSE Biology A course — cycling materials, ecosystems and communities, food webs and biomass transfer. Hosted by Rachel Carson Simulacrum.
Led by Rachel Carson Simulacrum
The question
How materials cycle through the abiotic and biotic components of an ecosystem — the carbon cycle, the water cycle, and the role of microorganisms in decomposition. Covers the factors that affect the rate of decomposition (temperature, water content, oxygen availability) and the distinction between aerobic and anaerobic decomposition.
Outcome
The student can explain the carbon and water cycles, describe the role of decomposers, and explain how temperature, water content and oxygen availability affect decomposition rate. (Biogeochemical cycling)
Sub-units
Led by Rachel Carson Simulacrum
The question
How ecosystems are organised — from individual organisms to populations, communities and the ecosystem as a whole. Covers the abiotic factors (temperature, light, moisture, soil pH) and biotic factors (predation, competition, food) that shape communities, and the forms of interdependence: predation, mutualism and parasitism.
Outcome
The student can describe the levels of organisation in an ecosystem and explain how abiotic and biotic factors affect communities through interdependence and competition. (Ecology)
Sub-units
Led by Rachel Carson Simulacrum
The question
How energy flows through ecosystems — trophic levels, producers and consumers, pyramids of biomass. Covers why biomass is lost between trophic levels (egestion, excretion, respiration), how to calculate the efficiency of biomass transfer, and why food chains rarely have more than four or five links.
Outcome
The student can describe trophic levels, explain pyramids of biomass and biomass loss between levels, and calculate the efficiency of biomass transfers. (Energy flow)
Sub-units