The living world
What's covered
Key facts
Cold environments
Visible effects of climate change on the Arctic include shrinking sea ice and thawing permafrost.
Ecosystems
A biome is a large-scale global ecosystem defined by its climate and characteristic vegetation.
Hot deserts
Afforestation (planting trees) reduces desertification by binding soil with roots and acting as windbreaks, lowering erosion rates.
Tropical rainforests
Buttress roots provide structural support for tall rainforest trees growing in shallow, nutrient-poor soils where deep root anchorage is impossible.
Cold environments
The Arctic tundra is fragile because it has a short growing season and recovers slowly from any damage.
Ecosystems
Tropical rainforests and hot deserts are both examples of biomes.
Hot deserts
The Thar Desert lies across north-west India and south-east Pakistan. The AQA specification does not prescribe it: it asks for "a case study of a hot desert" without naming one.
Tropical rainforests
A debt-for-nature swap is an agreement in which a country's external debt is cancelled (or reduced) in exchange for binding commitments to conserve part of its rainforest.
Cold environments
Cold environments are considered fragile ecosystems because they recover slowly from disturbance — a consequence of short growing seasons and cold-limited biological activity.
Ecosystems
The biotic components of an ecosystem are its living parts — plants, animals, fungi and bacteria.
Sample questions
A taste of the 62 questions in this topic, answers marked. Sign up to practise the full set with spaced repetition.
How have plants adapted to survive in tundra environments?
- •Developing thick waxy coatings to trap moisture in the dry air
- ✓Growing low to avoid wind damage, with shallow roots above permafrost
- •Growing tall to reach sunlight above the snow line
- •Storing large amounts of water in thick stems like desert cacti
What is a producer in a food chain?
- •an organism that breaks down dead organic matter
- •an organism that feeds on plants to get energy
- •an organism that hunts other animals for food
- ✓an organism that makes its own food through photosynthesis
Why do many desert animals behave nocturnally?
- •Food sources such as plants only grow at night in desert conditions
- •Predators in deserts are only active during the day
- •The desert surface is too hot to walk on after sunrise
- ✓To avoid the extreme daytime heat, conserving water and energy
What is meant by the nutrient cycle in a tropical rainforest?
- •Animals migrate through the forest distributing nutrients via waste
- •Deep roots extract nutrients from bedrock and transport them upward
- •Nutrients are carried from the canopy to the forest floor by rainfall
- ✓Rapid decomposition returns nutrients to topsoil, quickly absorbed by roots
What is the main threat to cold environments from economic development?
- •Agricultural development introduces invasive species that outcompete native plants
- •Mineral extraction causes earthquakes that crack the permafrost
- ✓Oil spills devastate the fragile ecosystem, which recovers very slowly
- •Tourism generates noise pollution that disrupts migratory bird patterns
What is a decomposer in a food chain?
- ✓an organism that breaks down dead organic matter into simpler substances
- •an organism that feeds on plants for energy
- •an organism that hunts other animals for food
- •an organism that makes its own food through photosynthesis
Try it for four weeks. Free.
One school. Unlimited classes. No card limit. No teacher limit. If your students aren't practising daily by the end of the trial, you owe us nothing.