9.2 Greenhouse gases
5 exam questions worth 10 marks. Write your answer, open the mark scheme, then give yourself the marks you earned. Your answers are saved on this device.
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Which of these is a greenhouse gas?
Choose one answer.
Correct Not quite: the answer is Methane
Mark scheme
C
Model answer
C: methane absorbs infrared radiation.
Explain how greenhouse gases keep the Earth warm.
Mark scheme
- short-wavelength radiation from the Sun passes through the atmosphere (1)
- Earth absorbs it and emits longer-wavelength / infrared radiation (1)
- greenhouse gases absorb this radiation (1)
- and re-emit it, some back towards the Earth (1)
Model answer
Short-wavelength radiation from the Sun passes through the atmosphere and warms the Earth. The Earth emits longer-wavelength infrared radiation. Greenhouse gases absorb some of this and re-emit it in all directions, including back to the Earth, so the Earth stays warm.
Give two human activities that increase the amount of methane in the atmosphere.
Mark scheme
any two from:
- cattle / livestock farming (1)
- rice growing (1)
- landfill sites (1)
Model answer
Cattle farming and landfill sites.
Explain why deforestation increases the amount of carbon dioxide in the atmosphere.
Mark scheme
- fewer trees to remove carbon dioxide by photosynthesis (1)
- trees are often burned, releasing carbon dioxide (1)
Model answer
Fewer trees means less carbon dioxide is removed by photosynthesis, and burning the trees releases more.
Explain why the greenhouse effect is important for life on Earth.
Mark scheme
- keeps the Earth warm enough for life / without it the Earth would be too cold (1)
Model answer
Without it, the Earth would be far too cold for most life.
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