CAIE A Level Biology 9700 · Transport in plants
A student observes a transverse section of the stem of a young herbaceous dicotyledonous plant. The xylem vessels appear as large, thick-walled cells with no living contents. Using your knowledge of the structure of xylem vessel elements, explain how their structure is adapted for the transport of water from the roots to the leaves.
5 marks, so the mark scheme is looking for about 5 separate creditworthy points. Making the same point twice in different words earns it once.
Explain means: Give the reasons or the mechanism: why or how something happens. Link each point to the next with because, so or which means. A list of facts with no links usually loses the reasoning marks.
Written by Markquill to follow the Cambridge International syllabus. Markquill is independent and is not affiliated with or endorsed by Cambridge International.