In plants Auxin concentration is maximum at:

Options

A. growing apex
B. only in Xylem and Phloem
C. in leaves
D. All of these

Answer

To determine where auxin concentration is maximum in plants, we can follow these steps:

1. **Understanding Auxin**: Auxin is a plant hormone that plays a crucial role in growth and development. It is primarily involved in cell elongation, apical dominance, and the regulation of various growth processes.

2. **Location of Maximum Concentration**: Auxin is known to be concentrated in areas of active growth. This includes regions where cell division and elongation are occurring.

3. **Identifying Growth Regions**: The primary sites of auxin concentration in plants are:
- **Apical Meristems**: These are found at the tips of stems and roots. The apical meristem is responsible for the primary growth of the plant, leading to an increase in height and depth.
- **Young Leaves**: Auxin is also present in young leaves, but its concentration is not as high as in the apical meristems.

4. **Conclusion**: Given that auxin is most concentrated in areas of rapid growth, the maximum concentration of auxin in plants is found at the **growing apices** (the tips of stems and roots).

**Final Answer**: Auxin concentration is maximum at the growing apices of plants.

---