Biology 9700 · AS & A Level · Structure of transport tissues

Structure of transport tissues — practice question

Water taken up from the soil solution by a plant's roots moves into xylem vessels and is then carried to the leaves and buds. Fig. 6.1 illustrates four key conditions needed for water to move efficiently from the roots up to the leaves of a plant.
(a)[1]

Identify the specialised cells that join end to end to make xylem vessels.

(b)[2]

Explain how tension is developed in the xylem vessels.

(c(i))[2]

As the xylem vessel cells develop, their walls become lignified. Explain why this feature is important for efficient water transport.

(c(ii))[1]

As xylem vessels develop, the end walls of the cells that make them up break down. This helps to minimise resistance to the movement of water. Describe one other major change that must happen to these cells so that their structure is suited to their function.

Worked solution & mark scheme

This 6-mark question has a full step-by-step worked solution and mark scheme. One marking point: “the xylem vessel elements” …

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