Which hormones promote activity of each other?

Answer

**Step-by-Step Solution:**

1. **Identify the Hormones**: The two hormones that promote each other's activity are Auxin and Cytokinin.

2. **Understanding Auxin**: Auxins are primarily involved in promoting root differentiation, cell division, cell elongation, and callus formation. They play a crucial role in the growth and development of plant roots.

3. **Understanding Cytokinin**: Cytokinins are hormones that induce cell division and differentiation. They are important for promoting shoot development and overall plant growth.

4. **Interaction of Auxin and Cytokinin**:
- Auxins are produced in the root meristems and stimulate meristematic cell division.
- Cytokinins facilitate the transition of cells from a meristematic state (undifferentiated) to a differentiated state (specialized).
- The presence of both hormones in balanced intermediate levels is essential for optimal growth and development.

5. **Hormonal Ratios**:
- A high ratio of cytokinin to auxin favors shoot production.
- Conversely, a high ratio of auxin to cytokinin favors root production.

6. **Conclusion**: Auxin and Cytokinin work synergistically to promote various aspects of plant growth and development, with each hormone influencing the activity of the other.

**Final Answer**: The hormones that promote the activity of each other are Auxin and Cytokinin.

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