AQA GCSE Biology (8461), Higher tier · Ecology › Biodiversity and human interaction
Practise Deforestation. 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.
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Deforestation means that less carbon dioxide is removed from the atmosphere. Name the process in trees that removes carbon dioxide from the atmosphere.
Photosynthesis
Complete the sentence. Large-scale deforestation in tropical areas has happened to provide land for cattle and ....................... fields, and to grow crops for ....................... .
rice; biofuels
Sample questions
Written for this site in the style of AQA exam questions. They are not taken from real past papers.
Question 1Easy5 marks
Large areas of tropical forest have been cut down.
(a) Which two are reasons for large-scale tropical deforestation? Tick (✓) two boxes.[2]
To provide land for cattle and rice fields
To grow crops for biofuels
To increase biodiversity
To reduce the carbon dioxide in the atmosphere
(b) Deforestation means that less carbon dioxide is removed from the atmosphere. Name the process in trees that removes carbon dioxide from the atmosphere.[1]
(c) Give one effect of deforestation on biodiversity. Give a reason for your answer.[2]
Show the answer and mark scheme
(a)Answer: To provide land for cattle and rice fields; To grow crops for biofuels
(b)Answer: Photosynthesis
photosynthesis
(c)
biodiversity is reduced / there are fewer species
because habitats / food / shelter for many species are destroyed / species may become extinct
Question 2Medium6 marks
In some tropical countries, forests are cleared by cutting down the trees and burning them. The land is then used to grow crops.
(a) Explain how clearing forest in this way increases the concentration of carbon dioxide in the atmosphere.[3]
(c) Some forests are cleared to grow crops for biofuels. Suggest one reason why some people support growing crops for biofuels.[1]
Show the answer and mark scheme
(a)
burning (combustion of) the trees releases carbon dioxide
microorganisms decay the remaining wood and roots, releasing carbon dioxide in respiration
fewer trees means less photosynthesis, so less carbon dioxide is removed from the air
carbon that was stored in the trees for many years is released
(b)
the habitats (food and shelter) of many species are destroyed
tropical forests contain very many species, but the crop field contains only one or a few species / species may become extinct
(c)
biofuels are renewable
they reduce the use of fossil fuels
they provide income / jobs for local people
Question 3Hard6 marks
In one study, clearing 1 hectare of tropical forest to grow a crop for biofuel released about 600 tonnes of carbon dioxide from the burning and decay of the trees and from the soil. Using the biofuel from 1 hectare instead of diesel reduces carbon dioxide emissions by about 7.5 tonnes per year.
(a) Calculate how many years it would take for the biofuel to make up for the carbon dioxide released by clearing the forest.[2]
(b) If the same crop is grown on land that is already farmland, about 60 tonnes of carbon dioxide are released per hectare when the crop is planted. Calculate the number of years needed in this case.[1]
(c) Evaluate growing biofuel crops on land cleared from tropical forest, compared with growing them on existing farmland.[3]
Show the answer and mark scheme
(a)Answer: 80 years
600 ÷ 7.5
80 (years)
(b)Answer: 8 years
60 ÷ 7.5 = 8 (years)
(c)
clearing forest releases much more carbon dioxide, so it takes 80 years (compared with 8 years) before the biofuel gives any benefit
clearing forest destroys habitats and reduces biodiversity
biofuels are renewable / reduce the use of fossil fuels
using existing farmland for biofuels leaves less land to grow food, which could threaten food security
a justified conclusion, e.g. biofuel crops should be grown on existing farmland, not on cleared forest