Question

The opening and closing of the stomatal pores depends upon ______.

Options

• oxygen

• water in guard cells

• temperature

•  concentration of CO₂ in stomata

Answer 1

The opening and closing of the stomatal pores depends upon water in guard cells.

Explanation:

The opening and closing of stomatal pores is entirely regulated by the turgidity (swelling or shrinking) of the surrounding guard cells, which depends directly on water movement:

• Opening the Pore: When water enters the guard cells, they take up water, swell, and curve outward. This turgid state pulls the inner walls apart, opening the stomatal pore.
• Closing the Pore: When water flows out of the guard cells, they lose their internal pressure, shrink, and straighten. This flaccid state allows the inner walls to collapse against each other, thereby closing the pore and preventing water loss.