Edexcel GCSE Biology, topic 9
Ecosystems and material cycles
This topic looks at how living things fit together in ecosystems, how to measure what lives where, and how energy flows through food chains. It also covers the effect humans have on biodiversity, and how carbon, water and nitrogen are cycled between living things and their surroundings.
Revision notes
Worksheet
FlashcardsSubtopics
Work through them in order. Each one has notes, exam questions and flashcards, and a PDF of each.
- 1Communities and interdependence Spec 9.1–9.4Levels of organisation in an ecosystem, abiotic and biotic factors, interdependence, parasitism and mutualism.NotesQuestions 5Flashcards 12
- 2Fieldwork and sampling Spec 9.5–9.6Core practical using quadrats and belt transects, and how to estimate the number of organisms in an area from raw data.NotesQuestions 3Flashcards 7
- 3Energy transfer in ecosystems Triple onlySpec 9.7B–9.8BHow energy is lost at each trophic level, how that limits food chains and shapes pyramids of biomass, and how to calculate efficiency.NotesQuestions 4Flashcards 6
- 4Human impacts, biodiversity and food security Spec 9.9–9.11BFish farming, non-indigenous species and eutrophication, the benefits of biodiversity and reforestation, and factors affecting food security.NotesQuestions 5Flashcards 12
- 5Material cycles Spec 9.12–9.15How materials cycle through ecosystems, with the carbon, water and nitrogen cycles, decomposers, desalination, fertilisers and crop rotation.NotesQuestions 6Flashcards 13
- 6Indicator species and decomposition Triple onlySpec 9.16B–9.19BIndicator species and pollution, factors affecting the rate of decomposition in food preservation and composting, and rate of decay calculations.NotesQuestions 5Flashcards 9
Whole topic
When you have done the subtopics: test yourself on everything, or print the lot.