Assertion: Blue light as a signal induces stomatal closure.
Reason: Blue light inhibits proton $\left[{\mathrm{H}}^{+}\right]$ transport.

1. Both assertion and reason are true and the reason is the correct explanation of the assertion.
2. Both assertion and reason are true but the reason is not the correct explanation of the assertion.
3. Assertion is true but reason is false.
4. Both assertion and reason are false.

Arrange the following events in the correct chronological order during opening of the stomata:
I. An uptake of potassium ions occurs into the guard cells.
II. A proton pump drives protons (H⁺) from the guard cells.
III. Diffusion of water occurs into the guard cell through osmosis.
IV. The two guard cells lengthen by bowing apart from one another.
V. Negative ions flux into the guard cells to balance the influx of potassium.
1. I, III, II, IV, V
2. I, II, V, III, IV
3. II, I, V, III, IV
4. II, V, I, III, IV

The presence of chloroplasts in guard cells is important because:
1. chloroplasts have a light sensitive receptor to direct stomatal opening.
2. photosynthesis provides the energy necessary for synthesis of cellulose microfibrils.
3. oxygenic photosynthesis produces oxygen necessary to power active transport.
4. ATP is required to power proton pumps in the guard cell membranes.