During secondary growth the amount of secondary xylem produced is more than the secondary phloem because

Options

A. the cambium is more active on the inner side
B. the cambium is more active on the outer side
C. the cambium is equally active on both sides but the xylem is needed more
D. the cambium has no role to play in this difference

Answer

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

### Step-by-Step Solution:

1. **Understanding Secondary Growth**:
- Secondary growth refers to the increase in the thickness of stems and roots in plants, primarily due to the activity of the vascular cambium.

2. **Role of Vascular Cambium**:
- The vascular cambium is a lateral meristem responsible for producing secondary xylem (wood) and secondary phloem (part of the bark).
- It is located between the primary xylem and primary phloem.

3. **Activity of Cambium**:
- The cambium is more active on the inner side compared to the outer side. This means that it produces more cells towards the inside of the plant.

4. **Production of Secondary Xylem and Phloem**:
- As the cambium divides, it produces secondary xylem towards the inside and secondary phloem towards the outside.
- Since the cambium is more active on the inner side, it results in a greater accumulation of secondary xylem.

5. **Comparison of Amounts**:
- The secondary xylem continues to accumulate year after year, leading to a significant increase in its volume compared to the secondary phloem.
- The secondary phloem does not accumulate as much because it is pushed outward and is often sloughed off or does not persist as long as secondary xylem.

6. **Conclusion**:
- Therefore, the primary reason that the amount of secondary xylem produced is greater than that of secondary phloem is due to the greater activity of the cambium on the inner side, resulting in more secondary xylem being produced.

### Final Answer:
The amount of secondary xylem produced is more than the secondary phloem during secondary growth because the cambium is more active on the inner side, leading to a greater production of secondary xylem.

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