Question

Stomata open when guard cells swell due to

• A. Decreased water potential
• B. Increased water potential
• C. Endosmosis by efflux of $K^{+}$ ions
• D. Endosmosis by influx of hydrogen ions

Answer 1

The correct option is A Decreased water potential

Stomata opens when guard cells swell due to decreased water potential. The rate of transpiration is high on a bright sunny day. The water is lost from guard cell which leads to decrease in the water potential of guard cell as compared to the surrounding cell. To stabilize the water potential in the guard cell water rushes from the neighbouring cell which creates a cohesion pull in the xylem vessels to pull the water up to the guard cell.

So, the correct answer is option A.