What is the fate of primary xylem in a dicot root showing extensive secondary growth?

Options

A. It is retained in the centre of the axis
B. It gets crushed
C. May or may not get crushed
D. It gets surrounded by primary phloem

Answer

To answer the question regarding the fate of primary xylem in a dicot root showing extensive secondary growth, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Primary Xylem**:
- Primary xylem is the first xylem formed during the primary growth of the plant. It is located centrally in the root.

2. **Secondary Growth in Dicot Roots**:
- In dicot plants, secondary growth occurs due to the activity of the vascular cambium, which is a lateral meristem. This growth leads to an increase in the thickness of the root.

3. **Role of Vascular Cambium**:
- The vascular cambium produces secondary xylem (wood) towards the inside and secondary phloem towards the outside.

4. **Position of Primary Xylem During Secondary Growth**:
- As the cambium produces secondary xylem, the primary xylem remains in its original position, which is at the center of the root.

5. **Comparison with Primary Phloem**:
- In contrast, the primary phloem gets pushed outward and may get crushed due to the expansion caused by secondary growth.

6. **Conclusion**:
- Therefore, the fate of the primary xylem in a dicot root undergoing extensive secondary growth is that it is retained in the center of the axis.

### Final Answer:
The primary xylem is retained in the center of the axis during extensive secondary growth in a dicot root.

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