Carbon dioxide is released into the atmosphere by a number of processes. Describe how carbon atoms that are present in atmospheric carbon dioxide can become part of the body of an animal.

Eduqas GCSE Biology — 6.2 The principle of material cycling · Describe · 4 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

Model answer (4 marks)

Plants absorb atmospheric CO₂ during photosynthesis, converting it into glucose and other carbohydrates.
The animal consumes the plant (or another animal that has eaten the plant).
In the animal’s digestive system, the carbohydrates are broken down, releasing carbon atoms.
These carbon atoms are then incorporated into the animal’s own tissues and body materials.

Examiner tips

  • Use the word ‘absorb’ for plants and ‘consume’ for animals. Show the flow: CO₂ → plant carbohydrates → animal tissues. Mention digestion as the step where carbon is released.
  • common_mistakes
  • :
  • Confusing photosynthesis with respiration. Omitting the digestion step. Using vague terms like ‘use’ instead of ‘incorporate’.

Mark scheme (4 marks)

  1. Plants (or other producers) absorb/take in carbon dioxide from the atmosphere during photosynthesis
  2. Carbon dioxide is used to make organic molecules / glucose / sugars / carbohydrates in the plant
  3. An animal eats / feeds on the plant (or another animal that has eaten a plant)
  4. The organic molecules are digested / broken down and the carbon is used to build the animal's own tissues / body materials

Key terms in this question

carbon dioxide

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