Explain how xylem tissue is adapted for its function in a plant.

Edexcel A-Level Biology A: Salters-Nuffield (9BN0) — 2.4 Plant structure and function · Explain · 5 marks · View as Markdown

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

Xylem is a type of vascular tissue found in plants. It transports water and mineral ions from the roots to the rest of the plant.

Model answer (5 marks)

Xylem vessels are hollow and contain no living cells, so water and mineral ions can flow through them without obstruction.
The cell walls of xylem vessels are thickened with lignin, giving the vessels structural strength and preventing collapse under the negative pressure generated by transpiration.
Xylem cells are arranged end‑to‑end to form continuous tubes, allowing water and mineral ions to move unimpeded from the roots up to the leaves.

Examiner tips

  • Use the word ‘hollow’ and ‘no living contents’ to show understanding of the structure. Mention lignin and its role in preventing collapse. Explain the end‑to‑end arrangement as a continuous tube for efficient transport.
  • Avoid vague phrases like ‘good structure’ – use specific terms such as ‘lignin’ and ‘negative pressure’.

Mark scheme (5 marks)

  1. Xylem vessels are hollow / have no living contents
  2. This allows water and mineral ions to flow through without obstruction
  3. Xylem cell walls are strengthened / reinforced with lignin
  4. Lignin provides structural support, preventing the vessels from collapsing under the tension / negative pressure of water movement
  5. Xylem cells are arranged end to end to form a continuous tube, allowing water and mineral ions to move up from roots to leaves

Key terms in this question

xylem

Related

More Plant structure and function questions

▶ Try answering this question with AI marking (free) →