AQA Biology 4.7.3.1

Biodiversity

Why a community with many different species holds together when one is lost, and why our own future depends on it.

Combined Science · Higher tier

Start here

A lawn and a meadow.

One field is a lawn of a single kind of grass. The field next to it is a wild meadow with dozens of different plants. A pest arrives that attacks only that one kind of grass.

If you had to guess, which field is more likely to be wiped out?

What biodiversity means

The variety of all the different species.

Biodiversity is the variety of all the different species of organisms on Earth, or within an ecosystem.

Every kind of organism counts: plants, animals, fungi and microorganisms. A field with a thousand rabbits and nothing else has very low biodiversity. A hedgerow with hundreds of different species has high biodiversity.

Stability

A great biodiversity ensures the stability of ecosystems by reducing the dependence of one species on another for food, shelter and the maintenance of the physical environment.

People depend on it

The future of the human species on Earth relies on us maintaining a good level of biodiversity.

Remove one species · watch the knock-on

Which community holds together?

If one species is removed, it can affect the whole community. Remove a species from each food web. A consumer is lost if every one of its foods is gone.

Species-poor · 5 species

Tap a species to remove it.

Species-rich · 10 species

Tap a species to remove it.

Human activity

Many human activities are reducing biodiversity.

Waste

Pollution of land, water and air kills plants and animals.

Deforestation

Clearing forest destroys the habitats of the many species that live there.

Global warming

Changing climate changes habitats faster than some species can cope with.

Only recently have measures been taken to try to stop this reduction. Each of these, and the measures, has its own lesson.

Think again · what counts

“Biodiversity is how many animals live somewhere.”

Your call

Choose

Which has the higher biodiversity?

Sort

Which threat is it?

Place each example with the human activity behind it.

Tap a card, then tap the box it belongs in. Tap a placed card to take it back.

Command words in this lesson

Define: The variety of all the different species of organisms on Earth, or within an ecosystem.
Explain: Name the dependence: food, shelter, or the physical environment.
Suggest: Use a food web to predict the knock-on of losing one species.

Key fact

Biodiversity is the variety of all the different species in an ecosystem. High biodiversity makes an ecosystem stable, because species depend less on any one other species for food, shelter and the physical environment.

Key note · AQA 4.7.3.1

Biodiversity

Biodiversity: the variety of all the different species of organisms on Earth, or within an ecosystem.
Plants, fungi and microorganisms count, not just animals.
High biodiversity makes an ecosystem stable by reducing the dependence of one species on another.
The dependences: food, shelter and the maintenance of the physical environment.
If one species is removed it can affect the whole community.
The future of humans relies on biodiversity. Many human activities reduce it; measures to stop this are recent.

Photograph this card. Tomorrow, cover it and say each line first.

Previous and next

Connects to

The water cycle

Ask MrBadmus

Not sure how to explain stability?

The food webs are simplified models: real consumers eat more foods, and real communities change in more ways than species being lost.