DP Biology (first assessment 2025)

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Question 22N.2.SL.TZ0.b

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Date November 2022 Marks available [Maximum mark: 4] Reference code 22N.2.SL.TZ0.b
Level SL Paper 2 Time zone TZ0
Command term Describe Question number b Adapted from N/A
b.
[Maximum mark: 4]
22N.2.SL.TZ0.b

Describe how plants affect the amount of carbon dioxide in the atmosphere.

[4]

Markscheme
  1. plants reduce the amount of carbon dioxide in the atmosphere by photosynthesis;
  2. carbon dioxide is fixed/converted into organic substances/sugars/ OWTTE;
  3. plants respire which releases carbon dioxide into the atmosphere;
  4. plant decomposition may release CO2
  5. carbon in dead plants is trapped/ stored in fossil fuels / peat
  6. combustion of plants/wood/ fossil fuels adds to the amount of carbon dioxide in the atmosphere;

OR Shows correct equation

Examiners report

In (b) many saw the words 'Carbon Dioxide' and immediately treated it as a long answer on greenhouse gases, thus putting their quality mark in jeopardy for superfluous content. Most were aware of photosynthesis removing CO2 from the atmosphere by fixing it into organic compounds and many mentioned plant respiration as increasing it. However, there were some disturbing answers where students mixed up photosynthesis and respiration. The question was about plants, but many answered in terms of animals.

Syllabus sections