AQA GCSE Combined Science (8464), Higher tier · Biology › Ecology › Biodiversity and the effect of human interaction on ecosystems
Practise Land use. 11 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.
Humans use land for building, quarrying, farming and dumping waste, leaving less for other species. You also need the example of peat bogs: why destroying them reduces biodiversity and releases carbon dioxide.
Grade by grade
What you need to be able to do, from the first marks up to the top grade.
3
Name ways humans use landBuilding, quarrying, farming and dumping waste.
4
Explain how land use reduces biodiversityHabitats are destroyed, so there is less space, food and shelter for other plants and animals.
5
State why peat bogs are destroyedPeat is dug up to produce garden compost.
6
Explain how destroying peat bogs affects biodiversityIt reduces the area of this habitat, so the variety of plant, animal and microorganism species there falls.
7
Explain how using peat releases carbon dioxideBurning peat, or its decay by microorganisms once it is exposed to oxygen, releases carbon dioxide.
7
Evaluate a decision about land useWeigh people's needs for homes, jobs and materials against the loss of habitats and biodiversity.
Notes
How humans use land
Humans reduce the amount of land available for other animals and plants by building, quarrying, farming and dumping waste.
As the human population grows, more land is needed for houses, roads, factories and food.
Destroying habitats leaves less space, food and shelter for other species, so biodiversity falls.
Farming large areas of one crop replaces many species with just one.
Peat bogs
Peat is made of partly decayed plant material. It forms in bogs, which are waterlogged and acidic, so there is little oxygen and decay is very slow.
Peat builds up extremely slowly, so it is used up far faster than it forms.
Peat bogs are the habitat of a particular range of plants, animals and microorganisms, many of them rare.
Peat bogs and other areas of peat are destroyed to produce garden compost. This reduces the area of the habitat and so reduces biodiversity.
Peat and carbon dioxide
Peat is a store of carbon, locked up in plant material that has not decayed.
When peat is burned as a fuel, combustion releases carbon dioxide.
When peat is drained or dug up and spread as compost, oxygen reaches it, so microorganisms decay it and their respiration releases carbon dioxide.
This adds to the carbon dioxide in the atmosphere, which contributes to global warming.
Using peat-free compost (e.g. made from garden waste, bark or coconut fibre) helps protect peat bogs.
Cheatsheet
Land is used for building, quarrying, farming and dumping waste
Less land for other species → lower biodiversity
Peat = partly decayed plant material that forms very slowly in waterlogged bogs
Peat is dug up to produce garden compost
Destroying peat bogs → less habitat → lower biodiversity
Burning or decay of peat → releases CO2
Peat-free compost helps protect peat bogs
How to answer each type of question
Recall: how humans reduce land for other species
2 marks3
Give two from: building, quarrying, farming, dumping waste (landfill).
Be specific: 'building houses' rather than 'using land'.
Example. Give two ways in which humans reduce the amount of land available for other animals and plants.
Show the model answer
Any two from: building (1); quarrying (1); farming (1); dumping waste / landfill (1)
Explain why destroying peat bogs is harmful
3 to 4 marks6
Biodiversity: the habitat is lost, so fewer species survive there.
Carbon: peat stores carbon, and burning or decay releases it as carbon dioxide.
Link carbon dioxide to global warming.
Peat forms very slowly, so it cannot be replaced quickly.
Example. Many gardeners use peat as compost. Explain why conservation groups want gardeners to stop using peat compost. (4 marks)
Show the model answer
Digging up peat destroys peat bog habitats (1), so the variety of species there / biodiversity falls (1). When peat is used as compost it decays, and the microorganisms release carbon dioxide by respiration (1). Carbon dioxide contributes to global warming (1). Also credit: peat forms very slowly, so it is not replaced.
Explain how peat releases carbon dioxide
2 to 3 marks7
Say that peat contains carbon from plants that did not fully decay.
Burning: combustion releases carbon dioxide.
Draining: oxygen reaches the peat, microorganisms decay it, and their respiration releases carbon dioxide.
Example. A peat bog is drained so that the land can be farmed. Explain why the land then releases more carbon dioxide. (3 marks)
Show the model answer
Draining lets air / oxygen into the peat (1). Microorganisms can now decay the peat faster (1). They respire, releasing the carbon stored in the peat as carbon dioxide (1).
Evaluate a land use decision
4 to 6 marks7
Give advantages for people (homes, jobs, food, materials).
Give disadvantages for other species (habitat loss, lower biodiversity) and for the environment.
Suggest how the harm could be reduced.
Give a judgement with a reason.
Example. A company wants to open a quarry on a hillside of grassland where a rare butterfly lives. Evaluate this plan. (4 marks)
Show the model answer
The quarry would provide stone for building and jobs for local people (1). The grassland habitat would be destroyed, so the rare butterfly could disappear from the area and biodiversity would fall (1). Lorries and machinery could cause pollution (1). Judgement with a reason, e.g. the plan should only go ahead if part of the grassland is protected or the site is restored afterwards (1).
Shortcuts and memory tricks
Land use, BQFW: Building, Quarrying, Farming, Waste.
Peat is a carbon bank: burn it or let it decay and the carbon comes back out as carbon dioxide.
Waterlogged means little oxygen, so decay is slow and peat builds up.
Where marks are lost
Giving only one of the two problems with using peat. Most questions want both: loss of habitat (biodiversity) and release of carbon dioxide.
Saying peat releases carbon dioxide 'naturally' without the process: combustion, or respiration by microorganisms.
Saying land use 'kills animals' without explaining habitat loss: less food, space and shelter.
Exam technique
For peat questions, cover both biodiversity and carbon dioxide unless told otherwise.
In 'evaluate' questions, give points on both sides and a justified conclusion.
Use the terms habitat, biodiversity, respiration and combustion.
Quick recall
Cover the answers and test yourself. The app has these as flashcards that come back just before you'd forget them.
Peat is dug from peat bogs. What is most of this peat used to produce?
Garden compost
Sample questions
Written for this site in the style of AQA exam questions. They are not taken from real past papers.
Question 1Easy5 marks
Humans reduce the amount of land available for other animals and plants.
(a) Which two human activities reduce the land available for other animals and plants? Tick (✓) two boxes.[2]
Building
Planting hedgerows
Quarrying
Creating nature reserves
(b) Give one other human activity that reduces the land available for other organisms.[1]
(c) Peat is dug from peat bogs. What is most of this peat used to produce?[1]
(d) Burning or decay of peat releases a gas that contributes to global warming. Name this gas.[1]
Show the answer and mark scheme
(a)Answer: Building; Quarrying
(b)
farming
dumping waste / landfill
(c)Answer: Garden compost
(garden) compost
(d)Answer: Carbon dioxide
carbon dioxide
Question 2Medium7 marks
Peat bogs are areas of waterlogged, acidic land. Dead plants in peat bogs decay very slowly, so they build up over thousands of years to form peat. Peat is dug up and sold to gardeners as compost.
(a) Explain why dead plants decay very slowly in peat bogs.[2]
(b) Explain how digging up peat bogs affects biodiversity.[2]
(c) When peat is used in gardens, it decays. Explain how this contributes to global warming.[3]
Show the answer and mark scheme
(a)
waterlogged, so there is very little oxygen
(and acidic, so) decomposers / microorganisms cannot survive or respire / work well
(b)
it reduces the area of peat bog habitat
so it reduces the variety of plant, animal and microorganism species that live there
(c)
the peat is exposed to oxygen, so microorganisms can decay it
the microorganisms release carbon dioxide in respiration / carbon stored for thousands of years is released as carbon dioxide
carbon dioxide increases the greenhouse effect / global warming
Question 3Hard8 marks
An area of peat bog of 3.0 km2 was drained. The peat was dug out to a depth of 2.0 m and sold as compost. Each cubic metre of peat contains about 50 kg of carbon. 1 km2 = 1 000 000 m2 and 1 tonne = 1000 kg.
(a) Calculate the volume of peat removed.[2]
(b) Calculate the mass of carbon in the peat removed. Give your answer in tonnes.[2]
(c) When peat decays, the carbon is released as carbon dioxide. 12 tonnes of carbon form 44 tonnes of carbon dioxide. Calculate the mass of carbon dioxide released if all of this peat decays.[2]
(d) Explain why the peat was stored in the bog for thousands of years but decays quickly when used in a garden.[2]
Show the answer and mark scheme
(a)Answer: 6.0 × 106 m3
3.0 × 1 000 000 = 3.0 × 106 m2
3.0 × 106 × 2.0 = 6.0 × 106 (m3)
(b)Answer: 3.0 × 105 tonnes
6.0 × 106 × 50 = 3.0 × 108 kg
3.0 × 105 (tonnes)
(c)Answer: 1.1 × 106 tonnes
3.0 × 105 × 44 ÷ 12
1.1 × 106 (tonnes)
(d)
in the bog the conditions are waterlogged / acidic / lack oxygen, so decomposers cannot work
in a garden there is oxygen (and it is less acidic / warmer), so microorganisms can decay the peat