KS3 · Biology

Conserving biodiversity

Sea ice is a polar bear's dinner table, bedroom and nursery. So what happens when it melts? And how can a seed vault and a log pile both save wildlife?

Build the web

Two routes to extinction, and the two jobs that fight back

Draw the arrows. First link the factors that push a species towards extinction (there are two separate routes). Then add an arrow from each conservation job to the part of the web it works on. Compare when you're done.

  1. Human activity: climate change, deforestation, building and quarrying, pollution and waste, overfishing
  2. The habitat changes
  3. The population gets smaller
  4. The gene pool gets smaller
  5. Extinction (outcome)
  6. Conservation job 1: protect habitats
  7. Conservation job 2: maintain the gene pool
Add a link

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What is biodiversity?

Which habitat has the most variety of life?

Biodiversity: the range of different species (different kinds of living organism) that live in a place. The more different species, the greater the biodiversity.

1 · Highest biodiversity3 · Lowest biodiversity

  1. Coral reef

  2. Arctic

  3. Tropical rainforest

Watch out: Biodiversity counts different species, not individual animals. A million penguins of one kind is still just one species.

Conservation in action

Which job does each method do?

Conservation scientists do two jobs. Tick the job (or jobs) each method does, then check.

  • A Protects habitats
  • B Maintains the gene pool
  1. A nature reserve
  2. Land protected completely, keeping other organisms, including humans, out
  3. Artificial nesting sites
  4. Bird and bat boxes in a garden or park
  5. A pond in a local park
  6. Long grass and a wildflower bed
  7. A log pile
  8. A zoo breeding programme using as many individuals as possible, releasing animals into a conserved habitat
  9. The Svalbard Global Seed Vault
  10. A cryobank storing eggs and sperm of the Mediterranean brown trout

Your judgement

Are zoos a good thing?

The claim

Zoos do more good than harm.

Place each piece of evidence to load the balance. Mark the strong ones — they count double.

  1. Zoos educate visitors about conservation.

    Evidence 1: does it support or challenge the claim?

  2. Zoos help to conserve endangered species through breeding programmes.

    Evidence 2: does it support or challenge the claim?

  3. Zoos are enjoyed by visitors.

    Evidence 3: does it support or challenge the claim?

  4. Zoos spend entry fees on their animals and on conservation.

    Evidence 4: does it support or challenge the claim?

  5. Cages may be small.

    Evidence 5: does it support or challenge the claim?

  6. Animals in zoos can get bored.

    Evidence 6: does it support or challenge the claim?

  7. Animals may not have mates for breeding.

    Evidence 7: does it support or challenge the claim?

  8. Animals may not live as they would in the wild.

    Evidence 8: does it support or challenge the claim?

Put it in your own words

Why bother keeping biodiversity?

Explain why it is important to maintain biodiversity. Give a reason linked to habitats and reasons linked to people. [4 marks]

0 words · your answer stays on this page and is not sent anywhere.

WHAT YOU'VE LEARNED

A quick recap of today's lesson.

A species needs a habitat that still fits its adaptations and a gene pool big enough to adapt. Conservation protects both.

What you need to know

  • Biodiversity is the range of different species living in a place: more different species means greater biodiversity.
  • Humans change habitats, mainly through climate change, deforestation, building and quarrying, pollution and waste, and overfishing.
  • When a habitat changes, organisms may no longer have the adaptations they need, as polar bears are finding with melting sea ice.
  • A gene pool is the range of genes in a species. The larger it is, the more likely the species is to be able to adapt when its habitat changes.
  • Conservation does two jobs: protect habitats, and maintain the gene pool (for example with breeding programmes and gene banks).

The big picture

Biodiversity is the variety of species living in a place. Human activity changes habitats, and a species can then be at risk in two ways: it may no longer be adapted to its changed habitat, and if its population shrinks, its smaller gene pool leaves it less able to adapt. Conservation fights back on both fronts, protecting habitats and maintaining the gene pool through breeding programmes and gene banks.

Key points

1Biodiversity is the variety of species in a place; a tropical rainforest has very high biodiversity and the arctic has low biodiversity.
2High biodiversity keeps habitats healthy, and it benefits people: future food supply, possible new medicines and mental wellbeing.
3Genes are units of genetic information, found in the nucleus and made of DNA; small differences in DNA make individuals of a species different.
4As an endangered population shrinks, its gene pool shrinks, so it is less able to adapt and more likely to face extinction.
5Habitats are protected by nature reserves, artificial nesting sites and small-scale features such as ponds, bird boxes and log piles.
6Gene banks store genetic material for future use: seed banks such as the Svalbard vault, and cryobanks storing embryos, eggs and sperm.
7Zoo breeding programmes work best with many individuals and a conserved habitat to release animals into, but views on zoos differ.

Worked example

Problem

Imagine a rare wildflower that grows in only one meadow. Only a few plants are left, and the meadow is about to be built on for new houses. Explain why the species is at risk, and suggest one conservation action for each threat.

⚠ Watch out

Thinking conservation just means keeping animals alive or increasing their numbers. Numbers matter partly because a bigger population keeps a bigger gene pool, so the species can adapt when its habitat changes, and the habitat itself must be protected too.

🧠

Memory hook

A species needs a HOME and a POOL: a home that still fits its adaptations, and a gene pool deep enough to adapt. Conservation guards both.

✓

Check yourself

Without looking back: name the two jobs conservation scientists do. Give one method for each, and name the one kind of method that can do both.

Flashcards

(15)
What is biodiversity?
The range (variety) of different species living in a place. The more different species, the greater the biodiversity.
Why does the arctic have low biodiversity but a coral reef high biodiversity?
The arctic is a harsh environment where very few species can live. A coral reef has lots of food, shelter and places for many species to reproduce.
What is conservation?
The process of protecting biodiversity and the environment. It helps keep habitats healthy.
Give three ways conservation benefits humans.
It helps maintain our future food supply; newly discovered organisms may provide medicines; and nature supports mental wellbeing.
Name five main ways humans change the numbers of species in a habitat.
Climate change; deforestation; using land to build houses and harvest materials (e.g. quarrying); pollution and waste; overfishing.
How is melting sea ice affecting polar bears?
Sea ice gives them food, shelter and a place to reproduce. As it melts and breaks up, polar bears are less well adapted to their environment.
What are genes, where are they found and what are they made of?
Units of genetic information inherited when organisms reproduce. They are in the nucleus of a cell and made of DNA (deoxyribonucleic acid).
Why can differences between individuals of a species matter when a habitat changes?
A difference can give an organism an advantage, so it is more likely to survive and pass that advantage on to its offspring.
What is a gene pool?
The range of genes (DNA) in a species: the genetic variation of the individuals in the population.
Why are small populations of endangered species at extra risk?
Their gene pool is smaller, so they are less able to adapt to habitat changes and more likely to face extinction.
Why is slow reproduction, as in elephants, a problem for an endangered species?
Genetic information takes a long time to pass to offspring.
Why did the Tasmanian tiger become extinct (one reason)?
Its gene pool was not big enough for it to adapt to a habitat that humans had changed. It died out in the wild in about 1926 and in zoos in 1936.
What is a gene bank?
A store of genetic (hereditary) material kept for future use, to preserve genetic diversity: for example collections of seeds, or stored plant and animal cells such as embryos.
What is the Svalbard Global Seed Vault?
A seed bank between Norway and the North Pole holding over one million seeds from across the world. Its very cold temperature helps preserve them.
What is a cryobank?
A gene bank that stores embryos, eggs and sperm at very low temperatures, e.g. eggs and sperm of the endangered Mediterranean brown trout.

Tap any card to flip it, or use Study as deck to go through them one at a time. In the full lesson these run as a spaced-repetition deck — you rate each card Hard, Good or Easy and the tricky ones keep coming back until they stick.

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How this lesson was checked. This KS3 Biologylesson was published through Lightbulb Learning's human-designed editorial process — the educational standards, accuracy rules and publication checks it must pass were authored and approved by Philip Halpin. It passed subject-specific assessment, automated educational checks and technical publication verification before going live (publication checks completed 1 October 2026). Published pages are monitored, human spot-checking is ongoing across the lesson library, and anything found wrong is corrected or withdrawn. How our lessons are made and checked. Spotted a mistake? Email hello@lightbulblearning.co and we'll review it.