Question

Stomata of a plant open due to:

• A. Influx of potassium ions
• B. Efflux of potassium ions
• C. Influx of hydrogen ions
• D. Influx of calcium ions

Answer 1

The correct option is A

Influx of potassium ions

During day time, the starch in guard cells is oxidized to phosphoenol pyruvate. It is then converted into malic acid, which breaks to $H^{+}$ and malate. $H^{+}$ ions move out of guard cells and $K^{+}$ ions enter with the help of the hydrogen-potassium ion exchange pump. Potassium ions draw in water by osmosis, which makes guard cells turgid and the stoma opens.