Question

Which of the following elements regulates the opening and closing of stomata?

• A. N
• B. K
• C. S
• D. P

Hint:

Potassium (\ce{K+}) controls stomatal opening/closing by driving water movement in guard cells.

Answer 1

The Correct Option is B

Potassium (K, option 2) is critical for regulating the opening and closing of stomata in plants. Stomata, small pores on plant leaves, control gas exchange and water loss. The movement of potassium ions (\ce{K+}) into and out of guard cells surrounding the stomata regulates their turgor pressure. When \ce{K+} enters the guard cells, water follows via osmosis, causing the cells to swell and the stomata to open, facilitating photosynthesis and transpiration. Conversely, when \ce{K+} exits, water leaves, reducing turgor and closing the stomata to conserve water. Other elements like Nitrogen (N), Sulfur (S), and Phosphorus (P) are essential for plant growth but do not directly regulate stomatal movement. Thus, option (2) is correct.