In the endodermis of root he passage cells have

Options

A. thick walls with casparian strips
B. thick walls without casparian strips
C. thin walls with casparian strips
D. thin walls without casparian strips

Answer

### Step-by-Step Solution:

1. **Understanding the Endodermis**: The endodermis is the innermost layer of the cortex in roots of vascular plants. It plays a crucial role in regulating the flow of water and nutrients into the vascular system.

2. **Identifying Passage Cells**: Passage cells are specialized cells located within the endodermis. They are typically found opposite the protoxylem strands and are crucial for the transport of substances.

3. **Characteristics of Passage Cells**:
- **Wall Thickness**: Passage cells are characterized by having thin walls. This is important for their function in facilitating the movement of water and nutrients.
- **Casparian Strips**: Unlike other cells in the endodermis, passage cells do not have Casparian strips. Casparian strips are bands of suberin that create a barrier to the passive flow of water and solutes, but passage cells lack this feature.

4. **Evaluating the Options**:
- **Option 1**: Thick walls with Casparian strips - Incorrect, as passage cells have thin walls and no Casparian strips.
- **Option 2**: Thick walls without Casparian strips - Incorrect, as passage cells have thin walls.
- **Option 3**: Thin walls with Casparian strips - Incorrect, as passage cells do not have Casparian strips.
- **Option 4**: Thin walls without Casparian strips - Correct, as this accurately describes the characteristics of passage cells.

5. **Conclusion**: The correct answer is that passage cells in the endodermis have thin walls without Casparian strips.