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Biodiversity is a measure of how many different species live in an ecosystem. Learn about biodiversity.

This lesson includes:

  • one video to help learn about biodiversity
  • two practise activities to help reinforce learning



Biodiversity means having as wide a range of different species in an ecosystem as possible. Areas like tropical rainforests have millions of different species and are very biodiverse. Other areas like the Polar Regions have far fewer species and are less biodiverse.

It is important to conserve the variety of living organisms on Earth. Not only do we have moral and cultural reasons for conserving endangered species, but conservation:

  • maintains the future possibility that plant species might be identified for medicines
  • keeps damage to food chains and food webs to a minimum
  • protects our future food supply

Watch this film from BBC News to learn about biodiversity and how hundreds of thousands of different species of animals and plants are potentially facing extinction. Feel free to use a pen and paper to make notes.

Laura Foster reports on a biodiversity emergency


Ecosystems are complex, and the many species within them depend on each other in different ways. They are interdependent.

Ecosystems with higher biodiversity have fewer species that depend on just one other for food, shelter and maintaining their environment. Therefore, ecosystems with higher biodiversity are more stable as they can more easily adjust to changes.

Even so, if the numbers of one species are affected, there are almost always knock-on consequences. A simple food chain is:

algae → zooplankton → sand eel → puffin → arctic skua

If the numbers of zooplankton are reduced by pollution, eg plastic waste, then more algae will grow and the population of other consumers will fall.

We are slowly realising that the future of our species on Earth depends on maintaining high biodiversity. Activities that create air and water pollution are reducing biodiversity in many ecosystems. Conservation of species and habitats by charities, governments and individuals helps to maintain the range of biodiversity.

Conservation measures

Some species in Britain are endangered, including the skylark, red squirrel and grass snake. They could be helped by conservation measures such as:

  • education programmes
  • captive breeding programmes
  • legal protection and protection of their habitats
  • making artificial ecosystems for them to live in

Plant species can also be endangered. Seed banks are a conservation measure for plants. Seeds are carefully stored so that new plants may be grown in the future.

Seed banks are an example of a gene bank. Gene banks are increasingly being used to preserve genetic material for use in the future. A cryobank is another type of gene bank. Embryos, sperm or eggs are stored at very low temperatures in liquid nitrogen (which is at a very chilly –196 °C). They can be thawed out later for use in breeding programmes.


A species becomes extinct when there are no more individuals of that species left. An extinct species has gone forever, although some scientists hope that they might bring back some extinct species using genetic engineering.

Changes in the environment may leave individuals less well adapted to compete successfully for resources such as food, water and mates. Sometimes an entire species may become unable to compete successfully and reproduce. These problems can lead to extinction. Here are some of the changes in the environment that can cause a species to become extinct:

  • a new disease
  • a new predator
  • a change in the physical environment, such as climate change
  • competition from another species that is better adapted, including competition from humans
Fossils have provided us with information on some extinct species

For example, dinosaurs became extinct millions of years ago. This was probably due to changes in the environment, but many species have become extinct more recently because of competition from humans.

Extinction can be avoided by:

  • Legislation preventing the hunting of endangered species.
  • International agreements, including those that plan to limit climate change.
  • Special programmes such as creating nature reserves to protect habitats.
  • Education that encourages people to do their part in protecting the environment.
Educating people to recyclel


Try the activities below to test your knowledge.

Activity 1

Biodiversity quiz

Test how much you know about biodiversity in this quiz.

Activity 2

Biodiversity activity

Have a go at this problem solving and comprehension activity from Beyond Secondary Resources. You can use a notepad and pen if you don't have a printer.

Read the posters and describe the problems raised by the information given, the impacts on biodiversity and ecosystem, and how to potentially solve these problems.

Biodiversity activity

There's more to learn

Have a look at these other resources around the BBC and the web.

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