The central lumens are obliterated in

Options

A. Xylem fibres
B. Pholem parenchyma
C. Xylem parenchyma
D. Sieve tubes

Answer

**Step-by-Step Solution:**

1. **Understanding the Term "Obliterated":**
- The term "obliterated" refers to the destruction or loss of the central lumen in plant cells. This is a key concept in understanding which plant structures are affected.

2. **Identifying the Structures:**
- The question lists several plant structures: xylem fibers, phloem parenchyma, xylem parenchyma, and sieve tubes. We need to determine which of these has obliterated central lumens.

3. **Analyzing Xylem Fibers:**
- Xylem fibers are known for their thickened walls due to lignification. Lignin is a complex organic polymer that strengthens the cell walls. As xylem fibers mature, the central lumen often becomes obliterated due to the thickening of the walls.

4. **Examining Phloem Parenchyma:**
- Phloem parenchyma cells have thin walls and do not undergo the same level of lignification as xylem fibers. Therefore, their central lumens remain intact.

5. **Considering Xylem Parenchyma:**
- Similar to phloem parenchyma, xylem parenchyma also has relatively thin walls and does not typically have obliterated lumens.

6. **Looking at Sieve Tubes:**
- Sieve tubes are specialized for transporting nutrients and have living cells with intact central lumens. They do not experience obliteration of the lumen.

7. **Conclusion:**
- Based on the analysis, the correct answer is that the central lumens are obliterated in **xylem fibers**.

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