In some old trees, though the central part (heart wood) is lost, the plant survives because

Options

A. The bark conducts food and water
B. The sapwood conducts water and secondary phloem conducts food
C. The cork conducts water and sapwood conducts food
D. The water is conducted through sapwood and there is no conduction of food

Answer

### Step-by-Step Solution:

1. **Understanding Heartwood**:
- Heartwood is the central part of a tree that consists of dead cells. It is typically darker in color and does not participate in the conduction of water and nutrients.

2. **Function of Heartwood**:
- Although heartwood provides structural support to the tree, it does not play a role in the transport of water and nutrients.

3. **Role of Sapwood**:
- Surrounding the heartwood is the sapwood, which consists of living cells. The sapwood is responsible for the conduction of water and nutrients throughout the tree.

4. **Secondary Phloem**:
- In addition to sapwood, the secondary phloem, which is also composed of living cells, conducts food (sugars and other nutrients) produced through photosynthesis from the leaves to other parts of the tree.

5. **Survival of the Tree**:
- Even if the heartwood is lost, the tree can still survive because the sapwood continues to function effectively in transporting water and nutrients. The presence of living cells in the sapwood and secondary phloem allows the tree to maintain its physiological functions.

6. **Conclusion**:
- Therefore, the reason some old trees can survive despite the loss of heartwood is that the sapwood and secondary phloem are still present and functional.

### Final Answer:
In some old trees, though the central part (heartwood) is lost, the plant survives because the sapwood conducts water and the secondary phloem conducts food.

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