Describe the roles of palisade mesophyll, spongy mesophyll, and phloem in a plant leaf.

AQA GCSE Biology (8461) — 4.2.3 Plant tissues, organs and systems · Describe · 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
- specialised for photosynthesis
Spongy mesophyll
- specialised for gas exchange
Phloem
- transports sugars via translocation
- carries sugars away from the leaf to other parts of the plant

Examiner tips

  • Use the exact terms ‘photosynthesis’, ‘gas exchange’, ‘translocation’, ‘sugars’
  • Show each tissue in a separate line or bullet to match the four marks
  • Mention direction of transport for phloem

Common mistakes

  • Confusing phloem with xylem or omitting the direction of transport
  • Using vague words like ‘help’ instead of ‘specialised for’
  • Failing to list all four points

Mark scheme (4 marks)

  1. Palisade mesophyll is specialised to carry out photosynthesis
  2. Spongy mesophyll is specialised for gas exchange
  3. Phloem transports sugars (through the process of translocation)
  4. Phloem transports sugars away from the leaf (to other parts of the plant)

Key terms in this question

palisade mesophyll · spongy mesophyll · phloem

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