Which sequence correctly illustrates the arrangement of layers from outside to inside in a dicot stem?

Options

A. Hypodermis `implies` Endodermis `implies` Pericycle `implies` Phloem `implies` Xylem
B. Endodermis `implies` Hypodermis `implies` Pericycle `implies` Xylem `implies` Phloem
C. Hypodermis `implies` Endodermis `implies` Pericycle `implies` Xylem `implies` Phloem
D. Endodermis `implies` Hypodermis ,`implies` Pericycle `implies` Phloem `implies` Xylem

Answer

To determine the correct sequence of layers from outside to inside in a dicot stem, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Outer Layer**: The outermost layer of a dicot stem is the **epidermis**. This layer serves as a protective barrier.

2. **Hypodermis**: Just beneath the epidermis is the **hypodermis**, which is typically made up of collenchyma cells providing support.

3. **Cortex**: Following the hypodermis, we have the **cortex**, which is composed of parenchyma cells and serves various functions including storage.

4. **Endodermis**: Inside the cortex, we find the **endodermis**, which is the innermost layer of the cortex. It regulates the movement of water and nutrients into the vascular system.

5. **Pericycle**: Below the endodermis is the **pericycle**, which is a layer of cells that can give rise to lateral roots and contributes to the formation of the vascular cambium.

6. **Phloem**: After the pericycle, we encounter the **phloem**, which is responsible for the transport of nutrients, particularly sugars.

7. **Xylem**: Finally, the innermost layer is the **xylem**, which transports water and minerals from the roots to the rest of the plant.

### Correct Sequence:
The correct sequence of layers from outside to inside in a dicot stem is:
- Epidermis
- Hypodermis
- Cortex
- Endodermis
- Pericycle
- Phloem
- Xylem

### Conclusion:
The correct answer is **Option 1**, as it accurately represents the arrangement of these layers.