Question

Choose the correct answers from the alternatives given :
Which one of the following does not cause opening of stomata ?

• A. Internal clock
• B. Light
• C. High carbon dioxide concentrations
• D. Movement of $K^{+}$ into guard cells

Answer 1

The correct option is A Internal clock

Factors affecting stomatal movement :

• Light - Stomata usually open in light and close in darkness. Therefore during the day, the rate of transpiration increases, while in the night, it decreases.

• Co2 concentration - Reduced Co2 concentration favors the opening of stomata, while the increase in CO2 concentration promotes closing of stomata.

• Movement of K+ into guard cell - Movement of K+ into guard cell will open stomata because K+ levels increase in the guard cells, the water potential of the guard cells drops, and water enters the guard cells thereby make stomata swollen or turgid.

So, the correct option is 'Internal clock'.