endodermis occurs in

Options

A. stems only
B. roots only
C. dicots stems and all types of roots
D. both monocot and dicot stems as well as roots.

Answer

**Step-by-Step Solution:**

1. **Understanding Endodermis**: The endodermis is a specialized layer of cells that is typically found in plant roots and, to some extent, in stems. It serves as a selective barrier regulating the flow of water and nutrients into the vascular system of the plant.

2. **Characteristics of Endodermis**:
- The endodermis is a single layer of cells.
- The cells are barrel-shaped and have thick walls.
- The radial and tangential walls of these cells have lignosubarized thickenings known as Casparian thickenings.

3. **Presence of Endodermis**:
- The endodermis is present in all types of roots (both monocot and dicot roots).
- In stems, the endodermis is found only in dicot stems, where it is referred to as the starch sheath.

4. **Analyzing the Options**:
- **Option 1**: "Stems only" - Incorrect, as the endodermis is not found in all stems.
- **Option 2**: "Roots only" - Incorrect, as it is also present in dicot stems.
- **Option 3**: "Dicot stems and all types of roots" - Correct, as the endodermis is present in all roots and dicot stems.
- **Option 4**: "Both monocot and dicot stems as well as roots" - Incorrect, as the endodermis is not present in monocot stems.

5. **Conclusion**: The correct answer to the question "endodermis occurs in" is **Option 3: dicot stems and all types of roots**.

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