AQA GCSE Combined Science (8464), Higher tier · Biology › Ecology › Biodiversity and the effect of human interaction on ecosystems
Practise Maintaining biodiversity. 14 exam-style questions plus unlimited generated ones on this subtopic, at up to four difficulty levels, with full mark schemes and a progress tracker. Free, no account needed.
What people are doing to reduce the damage humans cause to ecosystems and biodiversity, and why this can conflict with other needs. Expect to explain how each programme helps and to evaluate given information, often in a 4 to 6 mark question.
Grade by grade
What you need to be able to do, from the first marks up to the top grade.
3
Name programmes that protect biodiversityBreeding programmes, protecting rare habitats, hedgerows and field margins, reducing deforestation and carbon dioxide emissions, and recycling.
5
Explain how each programme helps biodiversitySay what the programme does and which species or habitats it protects.
6
Describe positive and negative human interactionsFor example, replanting hedgerows is positive, while removing them to make bigger fields is negative.
7
Explain conflicting pressures on maintaining biodiversityConservation costs money and uses land that people also need for food, homes, jobs and income.
8
Evaluate a conservation method using given dataWeigh the evidence of success against costs and limitations, then reach a justified conclusion.
Notes
Programmes to protect biodiversity
Scientists and concerned citizens have put in place programmes to reduce the negative effects of humans on ecosystems and biodiversity.
Breeding programmes for endangered species: animals are bred in captivity, e.g. in zoos, to increase their numbers, and some can be released back into the wild.
Protection and regeneration of rare habitats: e.g. protecting areas as nature reserves and restoring damaged peat bogs or wetlands, so the species that live there can survive.
Reintroducing field margins and hedgerows where farmers grow only one type of crop: these provide food, shelter and breeding sites for many wild plants, insects, birds and mammals, and link habitats together.
Reducing deforestation and carbon dioxide emissions (by some governments): this protects forest habitats and slows global warming.
Recycling resources rather than dumping waste in landfill: less land is used for landfill and fewer new resources need to be extracted.
Positive and negative interactions
Negative: pollution, destroying habitats, deforestation, removing hedgerows, and introducing species that outcompete native ones.
Positive: the programmes above, plus actions such as using peat-free compost and cleaning up polluted rivers.
Conflicting pressures
Protecting biodiversity can conflict with other needs, so decisions involve trade-offs.
Cost: breeding programmes and habitat protection are expensive, and the money is also needed for other things.
Land and food: hedgerows and field margins take up land that could grow crops, and a growing population needs food and homes.
Income and jobs: people may depend on activities that damage habitats, such as logging, quarrying or farming.
Limits of the methods: animals bred in captivity may have little genetic variation, may not survive in the wild, and cannot be released if their habitat has gone.
Cheatsheet
Breeding programmes for endangered species
Protection and regeneration of rare habitats
Reintroduce field margins and hedgerows where only one crop is grown
Reduce deforestation and carbon dioxide emissions (governments)
Recycle resources rather than dump waste in landfill
Conflicting pressures: cost, land for food and homes, jobs and income
How to answer each type of question
Name ways to maintain biodiversity
2 marks3
Choose from the five programmes in the specification.
Be specific: 'breeding programmes for endangered species', not just 'zoos'.
Example. Give two ways in which people are trying to reduce the negative effects of humans on biodiversity.
Show the model answer
Any two from: breeding programmes for endangered species (1); protecting or regenerating rare habitats (1); reintroducing hedgerows and field margins (1); reducing deforestation or carbon dioxide emissions (1); recycling rather than landfill (1)
Explain how a method increases biodiversity
2 to 3 marks5
Say what the method provides: habitat, food, shelter, breeding sites or more individuals.
Say which organisms benefit.
Link to more species surviving, so higher biodiversity.
Example. A farmer grows only wheat. Explain how planting hedgerows around the fields could increase biodiversity on the farm. (3 marks)
Show the model answer
Hedgerows contain many different plant species (1). They provide food, shelter and nesting sites for insects, birds and small mammals (1). So more species can live on the farm, increasing biodiversity (1). Also credit: hedgerows link habitats, so animals can move between them.
Explain conflicting pressures
2 to 4 marks7
State the conservation benefit.
State the competing need: money, land for food or homes, jobs, income.
Explain why the two conflict.
Example. Suggest why some farmers do not want to plant field margins of wild flowers. (3 marks)
Show the model answer
The margins take up land that could grow crops (1), so the farmer produces less food and earns less money (1). Planting and looking after the margins also costs money and time (1).
6-mark: evaluate a conservation programme
6 marks8
Use the data to judge whether it worked (numbers before and after).
Give advantages: species protected, numbers increased, habitat protected.
Give disadvantages: cost, released animals may not survive, habitat may still be threatened.
Reach a justified conclusion.
Example. A captive breeding programme for a rare bird released 60 birds into a protected reserve over 10 years. Over the same time, the wild population rose from 12 to 85. The programme cost £2 million. Evaluate the programme.
Show the model answer
Level-marked. A level 3 answer (5 to 6 marks) might include: the wild population rose from 12 to 85, so the programme appears to have worked; 12 + 60 = 72, which is less than 85, so some birds must be breeding in the wild; the reserve protects the habitat, so the birds can survive there; however, the programme was expensive and the money could have been used elsewhere; captive-bred birds may have little genetic variation; we do not know whether the population can survive without more releases. Conclusion: largely successful, because the population is much larger and is breeding in the wild, but it should be monitored.
Shortcuts and memory tricks
Five programmes: Breed, Protect, Hedge, Cut (deforestation and carbon dioxide), Recycle.
Evaluate = for, against, conclusion. No conclusion, no top level.
Hedgerows are wildlife corridors: food, shelter and a safe route between habitats.
Where marks are lost
Saying breeding programmes 'make more species'. They increase the number of individuals of an endangered species.
Naming a method without explaining how it helps biodiversity.
Ignoring the human side in 'conflicting pressures' questions: cost, food, land and jobs all matter.
Writing a one-sided answer to an 'evaluate' question.
Exam technique
Quote data from the question when judging whether a programme worked.
Use connectives such as 'however', 'on the other hand' and 'therefore'.
End an evaluation with a clear judgement and the main reason for it.
Sample questions
Written for this site in the style of AQA exam questions. They are not taken from real past papers.
Question 1Easy5 marks
Scientists and concerned citizens have set up programmes to reduce the negative effects of humans on ecosystems and biodiversity.
(a) Which two of these programmes help to maintain biodiversity? Tick (✓) two boxes.[2]
Breeding programmes for endangered species
Increasing the use of landfill
Removing hedgerows to make larger fields
Protecting and regenerating rare habitats
(b) Give one other programme that reduces the negative effects of humans on biodiversity.[1]
(c) Farmers who grow only one type of crop are encouraged to plant hedgerows. Explain how this increases biodiversity.[2]
Show the answer and mark scheme
(a)Answer: Breeding programmes for endangered species; Protecting and regenerating rare habitats
(b)
reintroducing field margins and hedgerows
reducing deforestation
reducing carbon dioxide emissions
recycling resources rather than dumping waste in landfill
(c)
hedgerows provide habitats (food and shelter) for many species
so more different species can live on the farm
Question 2Medium6 marks
A farmer planted strips of wild flowers along the edges of some fields (field margins). Ecologists counted insects in fields with and without these margins. {table} shows the results.
[object Object]
(a) Calculate how many times more bumblebees were counted per hour in fields with margins than in fields without margins.[1]
(b) Explain why the wildflower margins increase the number of insect species.[2]
(c) Suggest how the wildflower margins could benefit the farmer's crops.[2]
(d) Suggest one reason why some farmers do not plant field margins.[1]
Show the answer and mark scheme
(a)Answer: 5.75
46 ÷ 8 = 5.75
(b)
the margins provide food (nectar / pollen) and shelter / habitats
for many different species of insect
(c)
more pollinating insects, so more crop flowers are pollinated / higher yield
more predators of pests (e.g. ladybirds) live in the margins, so fewer pests
less need for pesticides
(d)
less land for crops, so a lower yield / less income
the cost of seeds / time to manage the margins
the margins might contain weeds or pests
Question 3Hard8 marks
A town council plans to build 400 new houses on an area of lowland heath. Lowland heath is a rare habitat, and the site is home to several rare species of reptile, bird and insect. The council says the houses are needed because the population of the town is growing. A conservation group suggests building the houses on the site of an old factory nearby instead. This would cost more, because the land would first need to be cleaned of toxic chemicals.
(a) Evaluate the two options for building the new houses. Include the effects on biodiversity in your answer.[6]
(b) If the heath site is used, suggest two ways the builders could reduce the effect on biodiversity.[2]
Show the answer and mark scheme
(a)
heath site: destroys a rare habitat, reducing biodiversity
heath site: rare species could become locally extinct / lose food and shelter
heath site: building reduces the land available for other animals and plants
heath site: cheaper / quicker, and houses are needed for the growing population
factory site: reuses land that has already been developed, so no rare habitat is lost
factory site: cleaning up toxic chemicals reduces land pollution, which benefits wildlife and people
factory site: costs more / takes longer
compromise, e.g. build on part of the heath and protect or regenerate the rest
a justified conclusion about which option is better
Marked with levels of response: the full level descriptors are in the app.
(b)
leave part of the site as a protected habitat / nature reserve
move the rare species to other suitable heathland
plant native species / create green spaces, hedgerows or wildlife corridors
create or regenerate heathland elsewhere to replace what is lost