Explain how the structure of a palisade mesophyll cell is adapted to carry out its function.

Cambridge International IGCSE Biology (0610) — 2.2 Levels of organisation · Explain · 4 marks · View as Markdown

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

Model answer (4 marks)

Palisade mesophyll cells are tall and elongated, allowing them to be closely packed at the top of the leaf just below the upper epidermis where light intensity is greatest. Their large number of chloroplasts means more sites for light‑absorbing pigments, so more photosynthesis can occur. The cell shape and position maximise light capture and provide a large surface area for chloroplasts to absorb photons.

Examiner tips

  • Use the word "adapted" and link structure to function explicitly. Mention the cell shape, chloroplast number and leaf position. Keep the answer concise – 4 marks allow a short paragraph.
  • common_mistakes
  • :
  • Failing to mention the cell height or leaf position. Using vague terms like "good shape" instead of "tall and elongated". Not linking chloroplasts to photosynthesis.

Mark scheme (4 marks)

  1. Palisade mesophyll cells contain a large number of chloroplasts
  2. Chloroplasts are the site of photosynthesis, so more chloroplasts allows more photosynthesis to occur
  3. Cells are tall / elongated and closely packed, increasing the amount of light absorbed
  4. Cells are positioned at the top of the leaf / below the upper epidermis where the most light is received

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