O-LevelGeographyThe natural environment2217/12 · Oct/Nov 2019 · Q622 Marks
Section C Answer one question from this section. (a) Study Fig. 6.1, which shows information about desertification. population growth increased demand for food, fuel and housing grassland over-grazed land over-cultivated trees cut down less rain falls plants do not grow soil becomes bare soil eroded by wind and water desertification [Figure 6.1]
- (a)(i)What is meant by desertification?[1]
- (a)(ii)Using information from Fig. 6.1 only, explain how the following can cause desertification. A Climate change B Population growth[2]
- (a)(iii)State two methods which people in rural areas of LEDCs could use to reduce desertification. For each of your chosen methods, explain why you think it will be successful. 1 2[4]
- (b)Study Fig. 6.2, which shows information about human influence on the greenhouse effect. Natural greenhouse effect CO2 Heat escapes into space CH4 N₂O Solar radiation Re-radiated heat heat Re-radiated More heat trapped Greenhouse effect increased by humans Less heat escapes into space Re-radiated heat CO2 Solar radiation greenhouse gases Atmosphere CH4 N2O More greenhouse gases [Figure 6.2]
- (b)(i)Using Fig. 6.2 only, explain how humans are influencing the natural greenhouse effect.[3]
- (b)(ii)Explain why greenhouse gases are building up in the atmosphere.[5]
- (c)Describe the problems caused by the increase in the greenhouse effect (global warming). You should refer to named areas affected.[7]
This question uses a diagram from the original paper, which isn't shown here. Open the full paper from the past papers archive to see it.
Mark scheme
Marking points from the official mark scheme (Oct/Nov 2019). The mark or mark type is shown in brackets.
- [1] The process by which fertile land becomes less productive/makes surface unsuitable for vegetation to grow/land becomes desert/dry/arid.
- [2] (A) Ideas such as: Less rain falls/drought/rapid evaporation; Plants do not grow/die/soil becomes bare, etc.
- [3] (B) Ideas such as: More food is needed; Areas are overgrazed/overcultivated; People need more fuel/homes/settlements; Trees are cut down/soil/land becomes bare.
- [4] Methods such as: Limit size of herds/rotate grazing land; Plant trees/shelter belts/afforestation; Contour ploughing/ploughing across slope; Education about agricultural techniques; Crop rotation; Terracing; Maintain soil cover/plant drought resistant plants; Mulching; Micro HEP project/small scale cookers. Explanations as appropriate to method such as: So, less overgrazing; Roots bind soil; So, less soil erosion; Less surface runoff; So, less deforestation; Improve soil fertility, etc.
- [3] Ideas such as: More/build up of greenhouse gases/ or named examples/chemical symbols; More heat trapped; Less heat escapes, etc.
- [5] Ideas such as: Burning of fossil fuels; E.g. oil/coal; Cars/engines; Aircraft emissions; Deforestation/forest fires; Reduces capacity of vegetation to convert carbon dioxide to oxygen/absorb carbon dioxide/gases; Methane from rice fields/grazing livestock; Thermal/coal/oil/gas power stations/electricity generation; Industry/manufacturing/industrialization, etc.
- [7] Comprehensive and accurate statements which describe the problems of global warming, including some place references. Content Guide: Answers are likely to refer to: Changing rainfall patterns/drought/desertification; Difficulty producing food; Lack of water supplies; Melting of ice caps/glaciers; Impacts on species/biodiversity/food chains; Flooding of coastal lowlands; Spread of tropical diseases to other areas; Loss of habitat; Heat stroke, etc.
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