Closure of stomata is brought about by

Options

A. Abscissic acid
B. Kinetin
C. Giberellic acid
D. IBA

Answer

**Step-by-Step Solution:**

1. **Understanding Stomata**:
- Stomata are small pores found on the surface of leaves. They play a crucial role in gas exchange (oxygen and carbon dioxide) and transpiration (loss of water vapor).

2. **Structure of Stomata**:
- Each stoma is surrounded by guard cells that control its opening and closing. These guard cells are essential for regulating the amount of gas exchange and water loss.

3. **Function of Guard Cells**:
- The guard cells swell or shrink to open or close the stomata. This process is vital for maintaining homeostasis in the plant.

4. **Identifying Plant Hormones**:
- The question asks which plant hormone is responsible for the closure of stomata. The options provided are:
- Abscisic acid
- Kinetin
- Gibberellic acid
- Indolebutyric acid (IBA)

5. **Role of Abscisic Acid**:
- Among the listed hormones, abscisic acid is known as the "stress hormone." It is primarily responsible for inducing the closure of stomata, especially during water stress conditions.

6. **Conclusion**:
- Therefore, the correct answer to the question is **abscisic acid**.

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