Element involed in stomatal regulation, its opening and closing is

Options

A. Zinc
B. Magnesium
C. Potassium
D. Iron.

Answer

**Step-by-Step Solution:**

1. **Understanding Stomatal Regulation**: Stomata are small openings on the surface of leaves that regulate gas exchange and transpiration in plants. Their opening and closing are controlled by guard cells.

2. **Role of Potassium Ions**: The primary element involved in the regulation of stomatal opening and closing is potassium (K+). When light hits the plant, photosynthesis occurs, leading to the production of ATP.

3. **Mechanism of Opening**:
- During the day, when light is present, ATP is generated through photosynthesis.
- This ATP powers the sodium-potassium pump in the guard cells, causing potassium ions to be actively transported into the guard cells.
- The influx of potassium ions creates a concentration gradient, leading to the movement of water into the guard cells by osmosis.
- As water enters, the guard cells swell, causing the stomata to open.

4. **Mechanism of Closing**:
- At night or in conditions of water stress, potassium ions are transported out of the guard cells (efflux).
- This loss of potassium ions causes water to leave the guard cells, leading to their flaccidity.
- As the guard cells become flaccid, the stomata close.

5. **Conclusion**: The element primarily responsible for the opening and closing of stomata is potassium. Thus, the correct answer to the question is potassium.

**Final Answer**: Potassium (K+)

---