Amount of secondary xylem is more than secondary phloem because

Options

A. cambium is more active on the outer side
B. cambium is more active on inner side
C. cambium has no role
D. cambium is active equally on both sides but xylem is required more.

Answer

To understand why the amount of secondary xylem is more than secondary phloem, we can break down the explanation into several steps:

### Step-by-Step Solution:

1. **Understanding Vascular Cambium**:
- The vascular cambium is a layer of meristematic tissue that is responsible for the secondary growth in plants. It is located between the xylem and phloem.

2. **Types of Cambium**:
- There are two types of cambium involved in secondary growth:
- **Intrafascicular Cambium**: This is found between the xylem and phloem within the vascular bundles.
- **Interfascicular Cambium**: This is formed from the dedifferentiation of parenchyma cells in the medullary rays, connecting the vascular bundles.

3. **Formation of Vascular Cambium**:
- The intrafascicular and interfascicular cambium join together to form a continuous ring known as the vascular cambium.

4. **Activity of Vascular Cambium**:
- The vascular cambium is more active on the inner side compared to the outer side.
- As it divides, it produces secondary xylem (wood) towards the inner side and secondary phloem (bark) towards the outer side.

5. **Comparison of Secondary Xylem and Phloem**:
- Due to the greater activity of the cambium on the inner side, significantly more secondary xylem is produced than secondary phloem. This is particularly evident in dicot stems, where the demand for water and nutrients is higher, necessitating more xylem.

6. **Conclusion**:
- Therefore, the amount of secondary xylem is more than secondary phloem because the cambium is more active on the inner side.

### Final Answer:
The correct reason for the greater amount of secondary xylem compared to secondary phloem is that **cambium is more active on the inner side**.

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