Calcium:
(a) Is required by meristematic and differentiating tissues
(b) Is needed during formation of mitotic spindle

Options

A. Only (a) is correct
B. Both (a) and (b) are correct
C. Only (b) is correct
D. Both (a) & (b ) are incorrect

Answer

**Step-by-Step Solution:**

1. **Understanding the Role of Calcium in Plants:**
- Calcium is classified as a macronutrient, meaning it is required by plants in larger quantities compared to micronutrients.
- It is absorbed by plants primarily in the form of calcium ions (Ca²⁺) from the soil.

2. **Calcium's Requirement in Meristematic and Differentiating Tissues:**
- Meristematic tissues are regions of active cell division and growth, while differentiating tissues are those that are undergoing specialization.
- Calcium is essential for the proper functioning and development of these tissues, as it aids in cell division and differentiation processes.

3. **Calcium's Role in Cell Division:**
- Calcium is crucial during cell division, particularly in the synthesis of the cell wall.
- It plays a significant role in the formation of the mitotic spindle, which is necessary for the organization and separation of chromosomes during cell division.

4. **Conclusion:**
- Based on the above points, both statements in the question are true:
(a) Calcium is required by meristematic and differentiating tissues.
(b) Calcium is needed during the formation of the mitotic spindle.
- Therefore, the correct answer is that both A and B are correct.