Describe5 marksChallenge
The table below shows the mean stomatal aperture (width of the stomatal pore, in arbitrary units) measured on the lower surface of leaves of a tomato plant over a 24-hour period under constant temperature and adequate water supply.
| Time (hours) | Aperture (arbitrary units) |
|---|---|
| 00:00 | 2 |
| 04:00 | 2 |
| 08:00 | 5 |
| 12:00 | 10 |
| 16:00 | 11 |
| 20:00 | 4 |
| 24:00 | 2 |
(a) Describe the pattern of stomatal aperture shown in the table.
(b) Explain the cellular mechanisms that cause stomata to open and close during this daily rhythm.
(c) If the plant were subjected to water stress, its stomata would close even during the day. Describe the role of abscisic acid (ABA) in this closure.