Question

Which essential nutrient is involved in regulating the opening and closing of the stomata of plants?

• A. Potassium
• B. Nitrogen
• C. Phosphorus
• D. Sulphur

Hint:

Potassium enhances drought resistance in plants by regulating stomatal closure and reducing water loss.

Answer 1

The Correct Option is A

Step 1: Function of stomata.
Stomata are pores on the leaf surface that regulate gas exchange and transpiration.
Their opening and closing depend on turgor pressure changes in guard cells.
Step 2: Role of Potassium.
Potassium ions (K$^{+}$) play a key role in controlling stomatal movement.
- When K$^{+}$ ions enter guard cells, water follows osmotically, guard cells become turgid, and stomata open.
- When K$^{+}$ ions exit, guard cells lose water, become flaccid, and stomata close.
Step 3: Analysis of options.
- (A) Potassium: Correct, regulates stomatal opening and closing.
- (B) Nitrogen: Important for protein and chlorophyll synthesis, not stomatal movement.
- (C) Phosphorus: Involved in energy transfer (ATP), not directly in stomatal regulation.
- (D) Sulphur: Needed for amino acids, not related to stomata.
Step 4: Conclusion.
Thus, potassium is the essential nutrient responsible for regulating stomatal opening and closing.