passage cells occur in

Options

A. Monocot root
B. Dicot root
C. Monocot stem
D. Both 1 and 2

Answer

### Step-by-Step Solution:

1. **Understanding Passage Cells**:
- Passage cells are specialized cells that are a type of endodermal cell.
- They are characterized by the absence of Casparian strips, which are typically present in endodermal cells.

2. **Location of Passage Cells**:
- Passage cells are found in the endodermis, which is the innermost layer of the cortex in roots.
- They are present in both monocot and dicot roots.

3. **Function of Passage Cells**:
- In monocot roots, passage cells are located opposite to the protoxylem elements. They are thin-walled and allow for the movement of fluids.
- In dicot roots, passage cells facilitate the movement of substances between the vascular tissue and the cortex.

4. **Identifying the Correct Option**:
- The question asks where passage cells occur. Since they are present in both monocot and dicot roots, the correct answer is that they occur in both types of roots.

5. **Conclusion**:
- Therefore, the correct answer to the question is **Option D: both 1 and 2 (Monocot Root and Dicot Root)**.