Which growth hormone is associated with stomatal movements

Options

A. Auxin
B. Gibberellin
C. Cytokinin
D. ABA

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks which growth hormone is associated with stomatal movements. Stomata are small openings on the surfaces of leaves that regulate gas exchange and transpiration in plants.

2. **Identifying the Growth Hormones**: The options provided are auxin, gibberellins, cytokinin, and abscisic acid (ABA). Each of these hormones has different roles in plant growth and development.

3. **Analyzing Each Hormone**:
- **Auxin**: Primarily involved in apical growth and elongation of cells.
- **Gibberellins**: Mainly responsible for promoting stem elongation and seed germination.
- **Cytokinin**: Involved in cell division and growth.
- **Abscisic Acid (ABA)**: Known for its role in stress responses, particularly in closing stomata during water stress.

4. **Focusing on Stomatal Movement**: Among the hormones, ABA is specifically known to influence stomatal closure. It acts by regulating the uptake of potassium ions in guard cells.

5. **Mechanism of Action of ABA**: When ABA is present, it inhibits the uptake of potassium ions in guard cells. This leads to a decrease in turgor pressure, causing the stomata to close. This is crucial for reducing water loss during drought conditions.

6. **Conclusion**: Based on the analysis, the growth hormone associated with stomatal movements is **abscisic acid (ABA)**.

**Final Answer**: Abscisic Acid (ABA)

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