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

Control and coordination in plants — practice question

Stomata in leaves react to environmental changes by opening and shutting. This controls the uptake of carbon dioxide and the loss of water.
(a)[4]

Describe how stomata open when light is present.

(b(i))[2]

Using Fig. 3.1, describe the link between the concentration of ABA in the xylem sap and stomatal conductance.

(b(ii))[4]

Suggest reasons for the results displayed in Fig. 3.1.

(c)[1]

State where transcription factors bind in order to increase the rate of transcription.

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This 11-mark question has a full step-by-step worked solution and mark scheme. One marking point: protons / $H^+$ ions are pumped out of guard cells into the cell wall

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