CAIE A Level Biology 9700 · Transport in plants
An electron micrograph of a transverse section through the stem of a tomato plant shows two adjacent cells in the phloem: a sieve tube element and a companion cell.
Compare the structure of a companion cell with that of a sieve tube element, and explain how each is adapted to its role in phloem transport.
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.
Compare means: Give similarities or differences between two things, and say which side each point belongs to. Write each point as a pair, for example: A is X, whereas B is Y. Two separate descriptions rarely earn the marks.
Written by Markquill to follow the Cambridge International syllabus. Markquill is independent and is not affiliated with or endorsed by Cambridge International.