Question

Guard cells are responsible for the opening and closing of stomata.

Answer 1

1. Opening and closing of stomata take place due to changes in the turgor of the guard cell.
2. The turgor changes in the guard cells are due to the entry and exit of water into and out of the guard cells.
3. During the day, water from the subsidiary cells enters the guard cells making them fully turgid causing the stomata to open.
4. During the nighttime, water from guard cells enters the subsidiary cells, making the guard cells flaccid, causing the stomata to close.