Biology 9700 · AS & A Level · Control and coordination in plants

Control and coordination in plants — practice question

Fig. 10.1 illustrates the arrangement of two guard cells.
(a)[3]

Identify the structures labelled A, B and C in Fig. 10.1.

(b)[4]

When water stress occurs, abscisic acid is released. This leads to stomatal closure and so lowers water loss by transpiration. Describe the role of abscisic acid in stomatal closure.

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This 7-mark question has a full step-by-step worked solution and mark scheme. One marking point: “A is the chloroplast” …

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