Describe the role of the xylem and phloem in a plant.

Eduqas GCSE Biology — 1.5.1 Plant structure and function · Describe · 4 marks · View as Markdown

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

Model answer (4 marks)

Xylem carries water and dissolved mineral ions from the roots up through the stem to the leaves.
Phloem transports the sugars (glucose, sucrose) produced by photosynthesis from the leaves to the rest of the plant, supplying energy to growing parts and storage sites.

Examiner tips

Use the exact terms ‘xylem’ and ‘phloem’. Show the direction of transport (roots to leaves for xylem, leaves to other tissues for phloem). Mention the substances carried (water/minerals vs sugars).
Keep the answer brief – each point counts as one mark.
Use UK spelling (e.g. ‘sucrose’, ‘phloem’).

Common mistakes

Confusing the direction of transport (e.g. saying xylem moves sugars). Using vague language such as ‘transport’ without specifying what is carried. Including extra information not asked for, such as the structure of vessels.

Mark scheme (4 marks)

Xylem transports water (and mineral ions/salts) through the plant
Xylem transports water from roots (upwards) to leaves / shoots
Phloem transports sugars / glucose / sucrose (food/products of photosynthesis) through the plant
Phloem transports sugars from leaves to the rest of the plant / to areas where they are needed (e.g. roots, growing regions)

Key terms in this question

xylem · phloem