Which of the following statements is correct regarding tracheids and vessels?

Options

A. Both are multicellular
B. Both are members of phloem
C. Lumen of tracheids is narrow but wide in vessels
D. Septa between vessels are intact but lost in tracheids

Answer

To determine which statement is correct regarding tracheids and vessels, let's analyze the characteristics of both structures step by step.

### Step 1: Identify the components of xylem
- **Tracheids and vessels** are both components of xylem tissue, which is responsible for the transportation of water and minerals in plants.

### Step 2: Compare the cellular structure
- **Tracheids**: These are elongated, dead cells that help in the conduction of water. They are narrower in diameter compared to vessels.
- **Vessels**: These are also involved in water conduction but are typically wider and consist of a series of vessel elements that are aligned end to end.

### Step 3: Analyze the lumen size
- The **lumen** (the internal space) of tracheids is narrower compared to that of vessels. This is because tracheids are designed for slower water transport and have a smaller diameter.

### Step 4: Evaluate the presence of septa
- **Septa**: In tracheids, the end walls can have perforations (septa), while in vessels, these septa are generally absent, allowing for a more efficient flow of water.

### Step 5: Review the statements
1. **Both are multicellular**: Incorrect, as tracheids are dead cells and vessels are formed from living cells.
2. **Both are members of phloem**: Incorrect, as both are members of xylem, not phloem.
3. **The lumen of tracheids is narrow but wide in vessels**: Correct, as discussed.
4. **The septa between vessels are intact but lost in tracheids**: Incorrect, as tracheids have septa while vessels do not.

### Conclusion
The correct statement regarding tracheids and vessels is: **"The lumen of tracheids is narrow but wide in vessels."**

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