Number of annual rings from base to apex of stem of dicot during secondary growth

Options

A. Increases
B. Decreases
C. Remain same
D. 1 and 2

Answer

To solve the question regarding the number of annual rings from the base to the apex of a dicot stem during secondary growth, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Annual Rings**:
- Annual rings, also known as growth rings, are formed in the stem of a plant due to the activity of the vascular cambium during secondary growth. Each ring typically represents one year of growth.

2. **Identifying the Structure**:
- In dicot plants, the vascular cambium is a lateral meristem that produces secondary xylem (wood) and secondary phloem. The growth rings consist of early wood (spring) and late wood (summer).

3. **Growth Pattern**:
- As a dicot plant grows, it adds new layers of xylem and phloem each year. The number of rings corresponds to the age of the tree; for example, a 100-year-old tree would have approximately 100 rings.

4. **Examining the Growth from Base to Apex**:
- When observing the annual rings from the base (bottom) of the stem to the apex (top), it is important to note that the growth rings are formed in a concentric pattern. The oldest rings are at the base, while the youngest rings are at the apex.

5. **Conclusion on the Number of Rings**:
- As you move from the base to the apex of the stem, the number of annual rings does not increase. Instead, the number of rings remains constant when counted, but the age represented by those rings decreases as you move upward.

6. **Final Answer**:
- Therefore, the number of annual rings from the base to the apex of a dicot stem during secondary growth **decreases**.