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Practice · Biology · 2025 syllabus · D4.3

IB Biology D4.3 Climate change: practice questions

6 exam-style questions on D4.3 Climate change, SL and HL, 1 marked HL: 3 multiple choice, 1 data-based, 1 short answer and 1 extended response. Each one comes with the mark scheme, a model answer and the reasoning behind every mark. Free with your email.

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D4.3-01 · Paper 1A style · multiple choice · 1 mark

Positive feedback in warming

Which is an example of a positive feedback loop that accelerates global warming? [1]

  1. Melting sea ice exposes darker ocean, which absorbs more solar radiation and warms further.
  2. Higher carbon dioxide concentrations increase photosynthesis, which removes carbon dioxide from the air.
  3. Warming makes sea level rise, because ice on land melts and the ocean water expands.
  4. Burning fossil fuels releases carbon dioxide, which absorbs long-wave radiation emitted by the Earth.
Show the answer and the reasoning

Answer: A. A is correct. Warming melts reflective ice, the darker water absorbs more radiation, and that causes more warming and more melting: the effect strengthens its own cause. B is a negative feedback, because the extra photosynthesis opposes the original rise in carbon dioxide. C is a consequence of warming, not a feedback: a higher sea level does not itself cause further warming. D is true, but it is the cause of the enhanced greenhouse effect, not a feedback loop: nothing about the warming increases the burning.

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The 6 questions in D4.3

  1. D4.3-01 Positive feedback in warmingPaper 1A style · multiple choice · 1 mark
  2. D4.3-02 Two threats to coralsPaper 1A style · multiple choice · 1 mark
  3. D4.3-03 What phenologists recordPaper 1A style · multiple choice · 1 mark · HL
  4. D4.3-04 Breeding on vanishing icePaper 2 style · short answer · 6 marks
  5. D4.3-05 Birds moving uphillPaper 1B style · data-based · 8 marks
  6. D4.3-06 Feedback, emissions and reefsPaper 2 style · extended response · 15 marks

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Every Biology and Chemistry question here is original, written for practice in the style of the papers set since the 2025 syllabus, with invented data. Developed independently from the International Baccalaureate Organization, which has not endorsed it. Found a mistake? Email vytis@limeadmissions.com with the question id.