CAIE A Level Biology 9700 · Transport in plants
Describe the transverse section of a herbaceous dicotyledonous leaf. In a typical leaf, the vascular bundles contain xylem and phloem. Explain how the structure of xylem vessel elements is adapted for the transport of water and mineral ions, and how the structure of phloem sieve tube elements and companion cells is adapted for the transport of organic solutes.
4 marks, so the mark scheme is looking for about 4 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.
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