AQA A-Level Environmental Science 3.1 The living environment: a complete overview of life, biodiversity and ecological cycles

What module 3.1 actually demands

The living environment is the ecological foundation of AQA A-Level Environmental Science. Module 3.1 runs from the physical conditions that made Earth habitable, through what biodiversity means and how we measure it, the great nutrient cycles of carbon and nitrogen, the methods used to conserve threatened species, and the way energy flows and matter cycles through the biosphere. The examiners test precise recall of definitions and processes alongside the ability to apply ecological principles to unfamiliar data and scenarios.

This guide walks through all five topics of the module, then sets out the exam patterns AQA repeats. Each topic has a matching dot-point page with practice questions; this overview ties them together.

Conditions for life and biodiversity

The module opens with the conditions for life on Earth: liquid water, a temperature range set by distance from the Sun, gravity strong enough to retain an atmosphere, and protection from radiation. Living organisms then changed the planet, producing the oxygen atmosphere and ozone layer, an idea captured by the Gaia hypothesis of self-regulation.

Biodiversity is examined at three levels (genetic, species and habitat). You must explain species richness and evenness, the index of diversity that combines them, and how diversity is estimated by sampling. The value of biodiversity (ecological, economic and ethical) is a recurring extended-answer theme.

The carbon and nitrogen cycles

The carbon cycle moves carbon through photosynthesis, respiration, decomposition and combustion, with long-term stores in fossil fuels, carbonate rocks and the oceans. The nitrogen cycle turns unreactive atmospheric nitrogen into usable forms by nitrogen fixation, then nitrification to nitrates, with denitrification and decomposition completing the loop. Knowing which organisms drive each step, and how human activity disrupts both cycles, is essential.

Conservation and the biosphere

Conservation of biodiversity asks why we conserve, what causes loss (habitat destruction, over-exploitation, pollution, invasive species and climate change), and how in-situ and ex-situ methods work, plus legislation such as CITES.

Life processes in the biosphere covers energy flow through trophic levels, the inefficiency of transfer (the ten percent rule), productivity (GPP and NPP), and the recycling of matter that keeps the biosphere supplied with nutrients.

How module 3.1 is examined

A typical AQA profile for The living environment:

• Definitions and recall. The three levels of biodiversity, the nitrogen-cycle processes, trophic levels, and in-situ versus ex-situ conservation.
• Data and calculations. Interpreting index-of-diversity values, sampling data, and energy-flow or productivity figures.
• Applied questions. Explaining how a named human activity disrupts a cycle, or evaluating a conservation strategy for a given species.
• Extended answers. Discussing the value of biodiversity, evaluating conservation methods, and explaining the Gaia hypothesis.

Check your knowledge

A mix of recall and applied questions covering module 3.1. Attempt them under timed conditions, then check against the solutions.

1. State two physical conditions that allowed life to develop on Earth. (2 marks)
2. Explain the difference between species richness and species evenness. (2 marks)
3. Name and describe the process that converts ammonium into nitrates. (2 marks)
4. Distinguish between in-situ and ex-situ conservation. (2 marks)
5. Explain why only about ten percent of energy passes between trophic levels. (3 marks)
6. Define net primary productivity. (2 marks)
7. Explain how burning fossil fuels disrupts the carbon cycle. (2 marks)
8. Give two causes of biodiversity loss. (2 marks)