Meristem is characterized by

Options

A. Isodimetric cells with cellulosic thin wall
B. Absence of intercellular space and vacuole
C. Absence of resrve food material, plastids, and ER
D. All of these

Answer

### Step-by-Step Solution:

1. **Definition of Meristem**:
- Meristems are specialized tissues in plants that consist of undifferentiated cells, which means these cells have not yet developed into specific types of cells. They are capable of continuous division and can differentiate into various types of plant tissues.

2. **Characteristics of Meristem**:
- **Isodiametric Cells**: Meristematic cells are typically isodiametric, meaning they have roughly equal dimensions in all directions. This shape allows for efficient growth and division.
- **Thin Cell Walls**: The cell walls of meristematic cells are thin and primarily composed of cellulose, which facilitates easy expansion and division.
- **Large Nuclei**: Meristematic cells have relatively large nuclei compared to their cell size, indicating high metabolic activity and the potential for division.
- **Absence of Vacuoles**: In meristematic cells, vacuoles are either absent or very small, which is different from mature plant cells that often have large central vacuoles.
- **No Intercellular Spaces**: Meristematic tissues do not have intercellular spaces, allowing for close packing of cells, which is essential for their function in growth.
- **Absence of Reserve Food Material**: Meristematic cells do not store reserve food materials, which is typical in differentiated cells that have specific functions.
- **Absence of Plastids**: Plastids, which are involved in photosynthesis and storage, are also absent in meristematic cells.

3. **Evaluating the Options**:
- **Option 1**: Isodiametric cells - Correct.
- **Option 2**: Absence of intercellular spaces - Correct.
- **Option 3**: Absence of reserve food material and plastids - Correct.
- **Option 4**: All of these - Since all previous options are correct, this option is also correct.

4. **Conclusion**:
- The correct answer is **Option D: All of these**, as all the characteristics listed in the options are true for meristematic tissues.