Heartwood differs from sapwood as

Options

A. It is peripheral
B. It is lighter in colour
C. It helps in conduction of water and minerals
D. It comprises of dead elements with highly lignified walls

Answer

### Step-by-Step Solution:

1. **Understanding Heartwood and Sapwood**:
- Heartwood and sapwood are two types of wood found in older woody trees.
- Heartwood is located at the center of the tree, while sapwood is found at the outer layer or periphery.

2. **Characteristics of Heartwood**:
- Heartwood consists of dead xylem vessels.
- These vessels are filled with tyloses, which are outgrowths that block the vessels.
- Heartwood is rich in deposits of resins and tannins, which contribute to its darker color.
- Since it is made up of dead xylem, heartwood is non-functional in terms of water conduction.

3. **Characteristics of Sapwood**:
- Sapwood is lighter in color and is located at the periphery of the tree.
- It consists of living xylem vessels that are functional and actively conduct water and minerals.
- Because it is composed of living cells, sapwood plays a crucial role in the tree's overall health and nutrient transport.

4. **Comparison of Heartwood and Sapwood**:
- Heartwood is darker, non-functional, and composed of dead xylem.
- Sapwood is lighter, functional, and composed of living xylem.

5. **Identifying the Correct Option**:
- The question asks how heartwood differs from sapwood.
- The correct characteristic that distinguishes heartwood is that it comprises dead elements with highly lignified walls.
- The other options (peripheral location, light color, and conduction of water) do not correctly describe heartwood.

### Conclusion:
The correct answer is that heartwood comprises dead elements with highly lignified walls.

---