Explain why a plant kept in complete darkness for several weeks will eventually die, even if it is given water and minerals.

OCR GCSE Biology A: Gateway Science (J247) — B1.2 What happens in cells (and what do cells need) · Explain · 4 marks · View as Markdown

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

A houseplant is placed in a sealed room with no light source. After several weeks, the plant dies.

Model answer (4 marks)

Without light, photosynthesis cannot occur.
Without photosynthesis, no glucose is produced.
Without glucose, cellular respiration cannot release energy (ATP).
Without energy the plant cannot carry out vital life processes and therefore dies.

Examiner tips

  • Use the exact sequence of cause–effect steps. Mention photosynthesis, glucose, respiration, ATP, vital processes. Keep each point brief and to the point.

Common mistakes

  • Confusing light with other energy sources. Forgetting to link glucose to ATP. Using vague terms like "energy" without specifying ATP.

Mark scheme (4 marks)

  1. Without light, photosynthesis cannot occur
  2. Without photosynthesis, no glucose is produced
  3. Without glucose, cellular respiration cannot release energy (in the form of ATP)
  4. Without energy the plant cannot carry out vital life processes and therefore dies

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