To answer the question regarding the plant hormones involved in growth-promoting activities, we will identify the key hormones and their roles in various processes such as cell division, cell enlargement, pattern formation, tropic growth, flowering, fruiting, and seed formation.
### Step-by-Step Solution:
1. **Understanding Plant Hormones**:
- Plant hormones, also known as phytohormones, are chemical substances that regulate various aspects of plant growth and development.
2. **Identifying Growth-Promoting Hormones**:
- The main plant hormones that promote growth include:
- **Auxins**: These hormones are primarily involved in cell elongation, apical dominance, and tropic responses (like phototropism and gravitropism).
- **Gibberellins**: These are crucial for promoting stem elongation, seed germination, and flowering.
- **Cytokinins**: These hormones promote cell division and are involved in shoot and root development.
3. **Roles of Each Hormone**:
- **Auxins**:
- Promote cell division and elongation.
- Play a role in pattern formation and tropic growth.
- **Gibberellins**:
- Stimulate stem elongation and flowering.
- Aid in seed germination and fruit development.
- **Cytokinins**:
- Promote cell division and influence the growth of shoots and roots.
- Help in delaying leaf senescence and promoting nutrient mobilization.
4. **Conclusion**:
- The three primary plant hormones involved in growth-promoting activities are **Auxins**, **Gibberellins**, and **Cytokinins**. These hormones work together to regulate various growth processes in plants.
### Summary of Plant Hormones:
- **Auxins**: Cell division, elongation, tropic growth.
- **Gibberellins**: Stem elongation, flowering, seed germination.
- **Cytokinins**: Cell division, shoot/root growth.
