Explain how the structure of a xylem vessel is adapted for its function of transporting water through a plant.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Model answer (4 marks)
Xylem vessels are hollow tubes with no cytoplasm or nucleus, allowing water to flow freely and unobstructed.
Their walls are thick and lignified, giving the vessels mechanical strength and preventing collapse under the tension generated by water moving up the plant.
Their walls are thick and lignified, giving the vessels mechanical strength and preventing collapse under the tension generated by water moving up the plant.
Examiner tips
- Use the word "hollow" and "no cytoplasm/nucleus" to show the lack of contents. Mention "unobstructed flow" to link structure to function. State that walls are "thick" and "lignified" and explain that this gives support and prevents collapse.
- common_mistakes
- :
- Forgetting to mention the absence of cytoplasm/nucleus. Describing the walls as thin or not lignified. Failing to link the thick walls to the prevention of collapse under tension.
Mark scheme (4 marks)
- Xylem vessels are hollow / have no cell contents (no cytoplasm / nucleus)
- This allows water to flow through freely / unobstructed
- Xylem vessels have thick, lignified walls
- Lignified walls provide support / prevent the vessel from collapsing under the tension of water moving upwards
Key terms in this question
Related
- All WJEC GCSE Biology (Wales) revision notes →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →
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