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B17.6 Maintaining Biodiversity

GCSE Combined Science · AQA · Chapter B17: Biodiversity and Ecosystems

A free GCSE Combined Science: Trilogy lesson for AQA (8464) from OBA School: programmes that protect species and habitats, and the conflicting pressures involved. Watch the video, read the explanation and worked examples, then try the revision questions. You can work through the full lesson, with every video, practice quizzes and printable worksheets with mark schemes, in our free online course.

What you will learn

  • Describe programmes that reduce the negative effects of humans on biodiversity
  • Explain how each programme helps to protect or increase biodiversity
  • Analyse data on the effect of conservation measures
  • Evaluate the conflicting pressures on maintaining biodiversity

Key words

  • Endangered species: A species with so few individuals left that it is at risk of becoming extinct.
  • Breeding programme: Carefully managed breeding of captive animals (e.g. in zoos) to increase their numbers and keep the widest possible gene pool.
  • Conservation: Protecting species and habitats from decline and extinction, so that biodiversity is maintained.
  • Monoculture: Growing one type of crop over a large area.
  • Hedgerow: A line of shrubs and trees grown together along the edge of a field.
  • Field margin: A strip of land around a field left uncultivated, often sown with wild grasses and flowers.

Ways to protect biodiversity

Scientists, governments, conservation charities and concerned citizens have set up programmes to reduce the harm humans do to ecosystems and biodiversity.

  • Breeding programmes for endangered species; How it helps biodiversity Numbers increase in captivity; breeding is managed to keep a wide gene pool and avoid inbreeding; animals can be released into protected habitats.
  • Protection and regeneration of rare habitats; How it helps biodiversity National parks, nature reserves and marine protected areas protect habitats such as coral reefs, heathland and peat bogs by law; damaged areas are restored.
  • Reintroducing field margins and hedgerows; How it helps biodiversity In areas with one crop (monoculture) these give food, shelter and nesting sites to many species, and link habitats together.
  • Reducing deforestation and CO₂ emissions; How it helps biodiversity Some governments limit forest clearing and the burning of fossil fuels. This protects habitats and slows global warming.
  • Recycling resources rather than dumping waste in landfill; How it helps biodiversity Less land is used for landfill and fewer raw materials are dug up or cut down.

Key fact: Individuals can help too: avoid pesticides and fertilisers in gardens, leave wild areas and log piles, grow wild flowers, compost food waste, and reduce, reuse and recycle.

Hedgerows and field margins

Many hedgerows were removed to make bigger fields that are easier to farm with large machines. Putting them back, with strips of wild flowers, gives insects pollen and nectar, birds food and nesting places, and small mammals shelter. Predators of crop pests, such as ladybirds and beetles, also live there.

Worked example: how much difference does a margin make?

No margin: 8 butterflies. Wildflower margin: 46 butterflies.
Increase = 46 − 8 = 38. Percentage increase = 38 ÷ 8 × 100 = 475%
Or: 46 ÷ 8 = 5.75 times as many butterflies.

Answer: 475% increase (5.75 times as many)

Conflicting pressures

Protecting biodiversity often costs money or conflicts with other needs. Decisions involve balancing these pressures.

  • Food; Example of conflict Farmers need high yields to make a living and feed people. Hedgerows and margins take land away from crops.
  • Money; Example of conflict Breeding programmes, guarding reserves and monitoring are expensive.
  • Jobs and development; Example of conflict Logging, mining and building bring jobs and income, but destroy habitats.
  • Local people; Example of conflict Farmers may kill predators that attack their livestock; people may hunt or cut wood to survive.
  • Fairness between countries; Example of conflict Richer countries cleared their own forests long ago. Is it fair to ask poorer countries not to do the same?

Exam tip: In an “evaluate” question give points for and against (biodiversity benefits and economic or social costs), then finish with a justified conclusion.

Common mistakes

  • Saying breeding programmes “save the species” on their own. Animals released into the wild also need a protected habitat to survive.
  • Describing hedgerows as just “nice to look at”. Explain that they provide food, shelter and nesting sites, and link habitats.
  • Forgetting the costs. Exam questions often ask about conflicting pressures such as food production, money and jobs.
  • Giving “stop pollution” as a method. Be specific: e.g. recycling to reduce landfill, or cutting CO₂ emissions.

Revision questions

Try these, then check your answers below each one.

Question 1. Which action would increase biodiversity on farmland where only one crop is grown? (Choose from: Removing hedgerows to make bigger fields, Planting hedgerows and wildflower field margins, Spraying more herbicide on field edges, Draining the farm pond.)

Answer: Planting hedgerows and wildflower field margins

Working: Hedgerows and margins give food, shelter and nesting sites, and link habitats together.

Question 2. The chart shows butterflies counted along field edges. How many times more butterflies were counted at edge D than at edge A?

Answer: 6.5 times

Working: D: 39 butterflies; A: 6 butterflies. 39 ÷ 6 = 6.5 times as many.

Question 3. True or false? Zoo breeding programmes are managed to keep a wide gene pool, which avoids inbreeding.

Answer: True

Working: True. Choosing unrelated parents keeps genetic variation high and avoids the genetic disorders caused by inbreeding.

Related lessons

Continue in the full course

This lesson is section B17.6 (AGCSC1706) of our free GCSE Combined Science course for AQA. In the full course you get every video for this section, a self-marking practice quiz, a printable worksheet with a mark scheme, chapter tests, and your progress saved. Go to the full GCSE Combined Science course.

 

 

 

 

 

 

 

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