AQA GCSE Biology 4.7 Ecology: a complete overview of ecosystems, biodiversity and food production

What module 4.7 actually demands

Ecology is about how organisms interact with each other and their environment, and how human activity affects the planet. The examiners reward clear understanding of interdependence, confident interpretation of food chains, cycles and graphs, the 10% biomass transfer idea, and balanced evaluation of human impact and food production.

This guide walks through the module and ties together the matching dot-point pages, each with its own practice questions.

Adaptations and competition

Organisms compete for resources: animals for food, mates and territory; plants for light, space, water and mineral ions. The environment has abiotic (non-living) and biotic (living) factors. Organisms survive through structural, behavioural and functional adaptations, and extremophiles are adapted to extreme conditions.

Organisation of an ecosystem

Organisms form populations and communities within an ecosystem, and they are interdependent. Food chains begin with a producer and pass through primary, secondary and tertiary consumers, with predator-prey numbers cycling. Materials are recycled through the carbon cycle and water cycle, with decomposers returning carbon dioxide and mineral ions. The required practical uses quadrats and transects to sample organisms.

Biodiversity and human impact

Biodiversity is the variety of all species; high biodiversity makes ecosystems stable. A growing human population and rising living standards increase pollution (land, water and air), deforestation and global warming, all of which reduce biodiversity. Breeding programmes, protecting habitats, reducing deforestation and recycling help maintain it.

Trophic levels and food production

Trophic levels run from producers up to apex predators, with decomposers recycling material. Only about 10% of biomass passes between levels because of respiration, movement and waste, calculated with the efficiency formula. Food security and sustainable methods (managing fish stocks, efficient farming, and biotechnology such as mycoprotein) aim to feed a growing population without destroying ecosystems.

How module 4.7 is examined

• Interpretation. Food chains, predator-prey graphs and the carbon and water cycles.
• Calculations. Biomass transfer efficiency and sampling estimates from quadrats.
• Evaluation. Human impact on biodiversity and the ethics of food production.
• Practical. Sampling with quadrats and transects.

Check your knowledge

A mix of recall and calculation questions covering module 4.7. Attempt them under timed conditions, then check against the solutions.

1. State two things animals compete for. (2 marks)
2. Give one example each of an abiotic and a biotic factor. (2 marks)
3. Name the three types of adaptation. (3 marks)
4. Define a community. (1 mark)
5. Explain the role of decomposers in the carbon cycle. (2 marks)
6. Define biodiversity. (1 mark)
7. A trophic level has 30000 kJ of biomass and the next has 3000 kJ. Calculate the efficiency of transfer. (2 marks)
8. Give one method of producing food more sustainably. (1 mark)