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Topic 9: Ecosystems and material cycles

3 dot points across 3 inquiry questions. Click any dot point for a focused answer with worked past exam questions where available.

How does energy transfer through an ecosystem, and how do humans affect biodiversity?

Explain energy transfer between trophic levels and biomass calculations, the positive and negative human impacts on biodiversity, the benefits of maintaining biodiversity, food security, and indicator species.
A focused answer to Edexcel GCSE Biology 9.7B to 9.11B and 9.16B, covering energy transfer and biomass efficiency between trophic levels, human impacts on biodiversity, conservation, food security and indicator species.
10 min answer →

How are ecosystems organised, and how do we estimate the number of organisms in an area?

Describe the levels of organisation in an ecosystem, how communities are affected by abiotic and biotic factors, interdependence including parasitism and mutualism, and sampling with quadrats and transects.
A focused answer to Edexcel GCSE Biology 9.1 to 9.6, covering the levels of organisation in an ecosystem, abiotic and biotic factors, interdependence, parasitism and mutualism, and estimating population size with quadrats and transects.
10 min answer →

How do carbon, water and nitrogen cycle through an ecosystem?

Explain how materials cycle through ecosystems, the importance of the carbon, water and nitrogen cycles including the role of microorganisms, and the factors affecting decomposition.
A focused answer to Edexcel GCSE Biology 9.12 to 9.15 and 9.17B to 9.19B, covering material cycles, the carbon cycle, the water cycle and potable water, the nitrogen cycle and the role of bacteria, and the factors affecting decomposition.
10 min answer →