In what respect, the pericycle of a dicot root differs from that of the dicot stem?

Options

A. Sclerenchymatous in root and collenchymatous in stem
B. Collenchymatous in root and parenchymatous in stem
C. Parenchymatous in root and sclerenchymatous in stem
D. Parenchymatous in root and collenchymatous in stem

Answer

To address the question regarding the differences between the pericycle of a dicot root and that of a dicot stem, we can break down the comparison into several key points:

### Step-by-Step Solution:

1. **Definition of Pericycle**:
- The pericycle is a layer of cells located just inside the endodermis in roots and just outside the vascular bundles in stems. It plays a role in the formation of lateral roots and contributes to the secondary growth in stems.

2. **Layering**:
- In dicot roots, the pericycle is typically a **single layer** of cells.
- In dicot stems, the pericycle is generally **multi-layered**.

3. **Cell Type Composition**:
- The pericycle in dicot roots is primarily composed of **parenchymatous cells**. These cells are living and involved in storage and transport.
- In contrast, the pericycle of dicot stems is composed of **sclerenchymatous cells**. These cells are usually dead at maturity and provide structural support.

4. **Vascular Bundle Arrangement**:
- In dicot roots, the vascular bundles are arranged in a **radial** pattern.
- In dicot stems, the vascular bundles are arranged in a **conjoined, open, or collateral** manner.

5. **Presence of Pith**:
- In dicot roots, the pith is either **small or absent**.
- In dicot stems, the pith is typically **large**.

### Summary of Differences:
- **Layering**: Single-layered in roots vs. multi-layered in stems.
- **Cell Type**: Parenchymatous in roots vs. sclerenchymatous in stems.
- **Vascular Arrangement**: Radial in roots vs. conjoined/collateral in stems.
- **Pith Size**: Small or absent in roots vs. large in stems.