CAIE A Level Biology 9700 · Transport in plants
A student examines a transverse section of a herbaceous dicot stem under a light microscope. They observe xylem vessel elements and phloem sieve tube elements with their associated companion cells. Describe the structural features of xylem vessel elements and phloem sieve tube elements, and explain how each feature is related to its function.
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.
Describe means: Say what happens or what something is like, in order and with detail. You are not being asked why. If there is data, quote it: name the trend, then give figures with units at the points where it changes.
Written by Markquill to follow the Cambridge International syllabus. Markquill is independent and is not affiliated with or endorsed by Cambridge International.