Describe5 marksChallenge
Table 1 shows the mean stomatal aperture (width of the pore) in leaves of a plant species over a 24-hour period under normal conditions (adequate water, alternating light/dark cycle, with light from 06:00 to 18:00).
| Time of day | Mean stomatal aperture (μm) |
|---|---|
| 00:00 | 0.5 |
| 06:00 | 1.2 |
| 12:00 | 8.5 |
| 18:00 | 6.3 |
| 24:00 | 0.4 |
Describe the mechanism by which guard cells regulate this daily pattern of stomatal opening and closing. In your answer, include the role of abscisic acid (ABA) in closing stomata during water stress.