Question

Turgidity in guard cells is controlled by

• A. Chloride
• B. Malic acid
• C. Potassium
• D. Potassium, chloride and malic acid

Answer 1

The correct option is D Potassium, chloride and malic acid

Opening and closure of the stomatal pores are mediated by changes in the turgor pressure of the two guard cells and the turgor pressure of guard cells is controlled by movements of ions and sugars into and out of the guard cells. When guard cells take up these solutes, the water potential (Ψ) inside the cells increases(creating a hypertonic solution), causing osmotic water flow into the guard cells. This leads to a turgor pressure increase causing swelling of the guard cells and the stomatal pores open. The ions that are taken up by guard cells are mainly potassium (K⁺) ionsand chloride (Cl⁻) ions.In addition, guard cells take up malic acid that contributes to the opening of stomatal pores.

So, the correct answer is option D.