How ecosystems function

• An ecosystem is the living and non-living parts of an area and how they link. A biome is a very large ecosystem, such as hot semi-arid grassland (savanna) or tropical rainforest.
• Producers make food from sunlight. Consumers eat other living things. Decomposers break down dead matter and return nutrients to the soil.
• A food web links many food chains, so it is a better model than a single chain.
• In a nutrient cycle, nutrients move between stores, such as living matter, litter and soil, with flows between them. Energy comes from the Sun and is lost as heat along the chain.
• Biodiversity is the variety of species in an area. Tropical rainforests have very high biodiversity.
• Hot semi-arid grassland (savanna) covers about 20% of the Earth's land. Rainfall is roughly 500 to 1,270 mm a year, falling in a wet season, with a dry season too. Typical plants include grasses, acacia and baobab. You also study one small-scale UK ecosystem, such as a sand dune system.

Ecosystem

The living and non-living parts of an area and how they link together.

Biome

A very large ecosystem, such as savanna or tropical rainforest.

Producer

A plant that makes food from sunlight.

Consumer

An animal that eats plants or other animals.

Decomposer

Fungi and bacteria that break down dead matter.

Food web

Many linked food chains in one ecosystem.

Biodiversity

The variety of species living in an area.

• Saying the nutrient cycle is the same as a food chain. A food chain shows who eats whom. A nutrient cycle shows how nutrients move between stores.
• Calling plants consumers. Plants are producers.
• Using a National Park, river or city as the small-scale UK ecosystem. Pick a small, defined area such as a dune system.
• Describing a climate without figures. Quote temperatures and rainfall.

8 questions, 16 marks. Answer, then press Check. The marking guide explains how the marks are worked out. Nothing is saved.