Maintaining biodiversity — AQA GCSE Combined Science
Test yourself on Maintaining biodiversity with AQA GCSE practice questions.
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Maintaining biodiversity explained
Human interactions with an ecosystem can raise or lower biodiversity.
Read the full explanation
Negative interactions include deforestation, draining peat bogs, overfishing, pollution and building on greenfield land; each removes habitats, food or breeding sites, so species numbers and variety fall. Positive interactions include replanting woodland, restoring wetlands, creating hedgerows and wildlife corridors, reducing pollution and setting aside nature reserves. To describe, name the interaction and say what changes in the ecosystem. To explain, link that change to species survival: fewer habitats means fewer niches, so populations shrink and some species disappear locally. For example, clearing hedgerows removes nesting sites and insect food, lowering bird diversity.
Scientists and concerned citizens have put in place programmes to reduce the negative effects of humans on ecosystems and biodiversity.
Programmes reduce human harm to ecosystems and biodiversity. Scientists collect data on species numbers, water quality and habitat extent, then advise on limits and restoration. Concerned citizens join surveys, volunteer conservation work, donate, campaign and change their own behaviour. Examples include breeding programmes for endangered species, seed banks, protected reserves, fishing quotas, recycling schemes and replanting projects. These programmes work by protecting habitats, reducing pollution and resource use, and reconnecting fragmented habitats so populations can recover. Their success is judged by monitoring: comparing species counts, water quality or habitat area before and after the programme. A programme may also involve laws, international agreements and education, because biodiversity loss crosses borders.
These include:
This lead-in line introduces a list of named strategies that humans use to protect biodiversity, so you must be able to recall and explain each one. Biodiversity means the variety of different species and the range of genetic variation within them, and it matters because stable ecosystems depend on many interlinked organisms. Human activity such as deforestation, pollution and overfishing reduces this variety, so conservation methods aim to keep populations viable and habitats intact. The listed methods are breeding programmes for endangered species, protection of rare habitats, reintroduction of hedgerows and field margins, reduction of deforestation and carbon dioxide emissions, and recycling rather than dumping waste. For each, link the action to its effect: for example, a zoo breeding programme raises numbers of a threatened animal, then offspring are released into protected habitat.
breeding programmes for endangered species
A breeding programme is a managed attempt to increase the numbers of an endangered species by controlling reproduction, usually in zoos, wildlife parks or specialist centres. Endangered means the population is so small or declining so fast that extinction is likely without help. Keepers select healthy, genetically diverse adults, provide veterinary care and controlled conditions, and record pedigrees so that closely related animals are not paired. Offspring may later be released into protected habitat, a process called reintroduction, once threats such as hunting or habitat loss have been reduced. The method maintains biodiversity by preserving species that might otherwise disappear and by keeping genetic variation within the captive population. Success depends on genetic diversity, suitable release sites and long-term protection of wild habitat.
protection and regeneration of rare habitats
Rare habitats support species found in few other places, so losing one can mean losing whole populations. Protection means keeping a habitat as it is: designating a site, restricting damaging activities such as drainage, ploughing or building, and controlling pollution and invasive species. Regeneration means actively restoring what has been degraded, for example clearing scrub from chalk grassland, blocking drainage ditches to rewet a bog, or replanting native trees. A useful method is to compare a site with a nearby undamaged reference area, then monitor indicator species over years. Protection and regeneration both raise biodiversity by giving rare species space to survive and breed.
reintroduction of field margins and hedgerows in agricultural areas where farmers grow only one type of crop
Monoculture means growing one crop over a large area, which reduces plant variety and removes food and shelter for many animals. Reintroducing field margins and hedgerows breaks up that uniformity. A field margin is an uncropped strip around a field, often sown with wildflowers or left as rough grass. A hedgerow is a line of shrubs and trees along a boundary. Together they provide nesting sites, nectar, berries and overwintering cover, and they act as wildlife corridors linking patches of habitat. This raises species richness and supports pollinators and natural predators of pests, which can also help the farmer.
reduction of deforestation and carbon dioxide emissions by some governments
Deforestation removes trees that absorb carbon dioxide during photosynthesis, so cutting fewer trees slows the rise of atmospheric carbon dioxide. Burning felled timber and clearing land also release carbon dioxide, so reducing deforestation lowers emissions from both loss of carbon sinks and combustion. Some governments act by designating protected forest reserves, enforcing logging bans, promoting sustainable timber, or paying landowners to conserve woodland. International agreements and national targets for lowering carbon dioxide emissions reinforce these measures. The overall effect is to slow habitat loss, protect biodiversity and reduce the enhanced greenhouse effect. For example, a country that bans clear-felling in a rainforest reserve preserves habitats and keeps stored carbon locked in living trees.
recycling resources rather than dumping waste in landfill.
Recycling processes used materials into new products instead of sending them to landfill. This reduces the volume of waste buried, so less land is taken up by landfill sites and habitats are less likely to be destroyed or polluted. Recycling also reduces the need to extract and process raw materials such as metal ores, crude oil and timber, which saves energy and lowers carbon dioxide emissions. Less landfill means less methane produced by decomposing waste, and fewer pollutants can leach into soil and water. For example, recycling aluminium cans uses much less energy than extracting aluminium from its ore, and recycling paper reduces the number of trees felled. Overall, recycling helps maintain biodiversity by reducing habitat destruction, pollution and resource extraction.
Your focus
- Describe one positive and one negative human interaction with an ecosystem.
- Explain how a named interaction changes biodiversity through habitat and niche availability.
- Apply the terms biodiversity, habitat, species and population accurately to a familiar example.
Show all 24 objectives
- Describe a programme that reduces human negative effects on ecosystems and biodiversity.
- Explain how scientists and concerned citizens contribute to such a programme.
- Explain how monitoring data can show whether a conservation programme is reducing harm.
- State what biodiversity means and why maintaining it is important.
- Identify several named strategies used to maintain biodiversity.
- Explain how a chosen strategy increases or protects biodiversity.
- Describe how a breeding programme for an endangered species is carried out.
- Explain how breeding programmes help maintain biodiversity.
- Evaluate the conditions needed for a breeding programme to succeed.
- State what is meant by a rare habitat and give one example.
- Distinguish protection from regeneration and describe one method of each.
- Explain how protecting or regenerating a rare habitat can increase biodiversity.
- Define monoculture and explain why it reduces biodiversity.
- Describe how field margins and hedgerows provide habitat and corridors for wildlife.
- Explain how reintroducing these features can increase biodiversity in arable farmland.
- Describe how deforestation affects atmospheric carbon dioxide concentrations.
- Explain how reducing deforestation can lower carbon dioxide emissions and protect biodiversity.
- Evaluate ways in which governments can reduce deforestation and carbon dioxide emissions.
- Describe how recycling reduces waste sent to landfill and conserves raw materials.
- Explain how recycling can lower energy use, carbon dioxide emissions and pollution.
- Evaluate the benefits and limitations of recycling compared with dumping waste in landfill.
Maintaining biodiversity exam tips
Marking Points
- Names a negative interaction such as deforestation, peat extraction, overfishing, pollution or urban expansion and states the habitat or resource lost.
- Names a positive interaction such as reforestation, wetland restoration, hedgerow planting, wildlife corridors or pollution reduction and states the habitat or resource gained.
- Explains the impact on biodiversity by linking habitat change to the number of available niches, so species variety and population sizes rise or fall.
- Uses a specific example, such as hedgerow removal reducing nesting sites and insect food so bird diversity falls.
- Distinguishes local effects, such as one pond being polluted, from wider effects, such as a river catchment losing several species.
- Applies the terms biodiversity, ecosystem, habitat, species and population correctly when describing the interaction.
- Identifies a programme such as a breeding programme, seed bank, nature reserve, fishing quota, recycling scheme or habitat restoration project.
- States the negative effect it targets, such as habitat loss, overexploitation, pollution or introduced species.
- Explains the mechanism: protecting or restoring habitat, limiting catches or emissions, or reconnecting fragmented habitats.
- Describes how scientists contribute, for example by surveying species, monitoring water quality or advising on sustainable limits.
- Describes how citizens contribute, for example by volunteering, recording wildlife, donating, campaigning or changing consumption.
- Explains how success is evaluated by comparing biodiversity data before and after the programme.
- Biodiversity is the variety of species and the genetic variation within populations, and maintaining it supports ecosystem stability.
- Named strategies include breeding programmes for endangered species, protecting rare habitats, reintroducing hedgerows and field margins, reducing deforestation and carbon dioxide emissions, and recycling resources rather than dumping waste.
- Each strategy works by increasing population size, preserving habitat area or quality, or reducing the human pressures that cause decline.
- Answers should link a specific method to a specific biodiversity benefit, such as captive breeding increasing numbers before release into the wild.
- Positive and negative human impacts on biodiversity can be compared, for example conservation versus deforestation or overfishing.
- Breeding programmes raise the number of individuals of an endangered species under controlled conditions.
- Captive populations are managed to preserve genetic diversity, for example by pairing unrelated individuals using pedigree records.
- Offspring can be reintroduced to protected wild habitat once the original threats have been reduced.
- The method maintains biodiversity by preventing extinction and conserving genetic variation within the species.
- Success depends on factors such as genetic diversity, suitable habitat and continued protection after release.
- Protection keeps an existing rare habitat intact by limiting damaging human activities such as building, drainage, ploughing and pollution.
- Regeneration restores a degraded habitat through active management, for example rewetting a bog or clearing scrub from chalk grassland.
- Rare habitats matter because they contain specialised species that cannot easily survive elsewhere, so damage can cause local extinction.
- Monitoring against a reference site or using indicator species shows whether protection and regeneration are working.
- Both approaches maintain biodiversity by preserving or rebuilding the range of species and the genetic variation within them.
- Monoculture reduces biodiversity because a single crop supports fewer species than a varied plant community.
- Field margins are uncropped strips around fields that provide food, shelter and nesting sites for invertebrates, birds and small mammals.
- Hedgerows are lines of shrubs and trees that give cover, berries and corridors for wildlife moving between habitats.
- Reintroducing these features increases species richness and can support pollinators and predators of crop pests.
- The benefit is assessed by comparing species counts in fields with margins and hedgerows against fields without them.
- Deforestation reduces the number of trees available to absorb carbon dioxide by photosynthesis, so atmospheric carbon dioxide can rise.
- Clearing forest by burning releases carbon dioxide that was stored in the trees, adding to emissions.
- Reducing deforestation protects habitats and the species living there, helping to maintain biodiversity.
- Governments can reduce deforestation by creating protected areas, enforcing logging restrictions, promoting sustainable timber and supporting replanting.
- Lower carbon dioxide emissions slow the enhanced greenhouse effect and the associated climate change.
- Government action may include international agreements, national emission targets, taxes or incentives for forest conservation.
- Recycling reduces the quantity of waste sent to landfill, so less land is used for waste disposal and habitats are preserved.
- Recycling reduces the need to extract raw materials such as metal ores, crude oil and timber, conserving natural resources.
- Recycling often uses less energy than producing materials from raw sources, lowering carbon dioxide emissions.
- Less landfill reduces methane production from decomposing waste and reduces leaching of pollutants into soil and water.
- Protecting habitats from landfill and pollution helps maintain biodiversity and ecosystem stability.
- Recycling schemes may require collection, sorting and processing, which can have their own energy costs and limitations.
Examiner Tips
- 💡Use a two-part answer: first describe the interaction, then explain the biodiversity impact using because or so.
- 💡Choose one negative and one positive interaction and develop each with a named organism or habitat.
- 💡Link answers to niches and habitats; these ideas carry the explanation beyond simple description.
- 💡Name the programme, state the negative effect it targets, then explain how it reduces that effect.
- 💡Include one scientist role and one citizen role to cover both parts of the statement.
- 💡Mention monitoring data as evidence that a programme is working.
- 💡Use the command word to judge depth: describe needs the method, explain needs the method plus its effect on biodiversity.
- 💡Name at least three different strategies and give a distinct benefit for each rather than repeating one idea.
- 💡Link answers to a real context, such as hedgerows providing corridors that connect isolated populations.
- 💡Explain the sequence: select diverse adults, breed under controlled conditions, then reintroduce to protected habitat.
- 💡Use the term genetic diversity when explaining why pedigree records matter.
- 💡Apply the idea to a named example, such as breeding programmes for tigers or pandas, to show understanding.
- 💡Name a specific rare habitat and one threat to it, then link each management action to the species it helps.
- 💡Use the words protection and regeneration separately so the examiner can see you know the difference.
- 💡When asked to evaluate, compare the site before and after management and mention a control or reference area.
- 💡Link each feature to a specific need, such as nectar for pollinators or berries for birds in winter.
- 💡Use the term monoculture correctly and explain why it lowers biodiversity before describing the fix.
- 💡If asked to evaluate, mention that hedgerows and margins take land out of production, so there is a trade-off with yield.
- 💡Link each government action to a specific effect on carbon dioxide or biodiversity rather than listing actions alone.
- 💡Use the phrase carbon sink when explaining how forests store carbon, and state that burning releases the stored carbon.
- 💡When asked to evaluate, give one benefit and one limitation of government action, such as cost or difficulty of enforcement.
- 💡Compare recycling with landfill by naming the specific harm avoided, such as habitat loss, methane or leaching.
- 💡Use a named material example, such as aluminium or paper, to show how recycling saves energy or trees.
- 💡If asked to evaluate, state one advantage and one limitation of recycling rather than only listing benefits.
Common Mistakes
- Treating any planting as automatically positive: state which species benefit and why, because planting a single non-native species can reduce variety.
- Confusing habitat loss with extinction: habitat loss lowers biodiversity and may cause local extinction, but global extinction needs wider evidence.
- Describing an interaction without its impact: always add the consequence for species number or population size, not just the activity.
- Claiming a programme removes all harm: state that it reduces or limits negative effects, because some impact usually remains.
- Naming a programme without its mechanism: add how it protects habitats or species, otherwise the answer stays descriptive.
- Assuming only scientists act: include citizen roles such as surveys, volunteering and campaigning, because the statement names both groups.
- Treating biodiversity as simply the number of individual organisms; correction: it is the variety of species and genetic variation, not total abundance.
- Listing a method without explaining how it maintains biodiversity; correction: always add the mechanism, such as habitat protection preserving breeding sites.
- Confusing recycling with reducing carbon dioxide emissions; correction: recycling cuts waste and resource extraction, while lowering emissions mainly limits climate-related habitat change.
- Assuming captive breeding alone guarantees survival; correction: released animals also need protected habitat and reduced threats.
- Ignoring genetics and pairing close relatives; correction: inbreeding reduces genetic diversity and can lower health and survival.
- Thinking breeding programmes replace habitat protection; correction: they support species while habitats are restored and are most effective alongside habitat conservation.
- Confusing protection with regeneration: protection maintains a habitat as it is, while regeneration actively repairs damage.
- Assuming rare habitats are only remote wilderness: rare habitats can be small local sites such as a fen or heathland near a town.
- Thinking one survey proves success: monitoring must be repeated over time to show a real trend in species numbers.
- Saying hedgerows only look attractive: they are habitat and wildlife corridors, not just scenery.
- Forgetting that field margins are left uncropped: if they are sprayed or cropped they lose much of their value.
- Claiming biodiversity rises instantly: new hedgerows take years to mature and support a full community.
- Thinking deforestation only affects habitats and not atmospheric carbon dioxide; correction: fewer trees means less photosynthesis, so less carbon dioxide is removed, and burning adds carbon dioxide.
- Confusing deforestation with planting trees; correction: deforestation is the removal of forest, while replanting or afforestation is a separate conservation action.
- Assuming all governments act in the same way; correction: some governments introduce laws, protected areas or incentives, while others may not, so the statement says some governments.
- Thinking recycling only saves resources and has no effect on biodiversity; correction: less landfill and less extraction protect habitats and reduce pollution.
- Believing all materials can be recycled endlessly; correction: materials such as paper fibres shorten with each cycle, and some plastics are difficult to recycle.
- Assuming recycling has no environmental cost; correction: collection and processing use energy and transport, so the benefit depends on the material and scheme.