Which is wrong about sieve tube elements ?

Options

A. (a) Peripheral cytoplasm and large vacuole.
B. (b) Perforated end wall becomes impregnated with lignin.
C. (c) P-proteins evenly distributed throughout lumen.
D. (d) Absence of nucleus at maturity.

Answer

To determine which statement about sieve tube elements is incorrect, we will analyze each option provided in the question.

### Step-by-Step Solution:

1. **Understanding Sieve Tube Elements**:
- Sieve tube elements are specialized cells in the phloem tissue of plants. They are responsible for the transport of sugars and nutrients from the source (usually leaves) to the sink (other parts of the plant).

2. **Analyzing Option A**:
- **Statement**: "Peripheral cytoplasm enlarged by cure."
- **Evaluation**: This statement is correct. Sieve tube elements have a peripheral cytoplasm that is indeed enlarged.

3. **Analyzing Option B**:
- **Statement**: "Perforated end wall become impregnated with lignin."
- **Evaluation**: This statement is incorrect. The end walls of sieve tube elements do not become lignified; they remain as living cells and are not impregnated with lignin. Instead, they have sieve plates that facilitate the flow of sap.

4. **Analyzing Option C**:
- **Statement**: "P proteins evenly distributed throughout the lumen."
- **Evaluation**: This statement is correct. P proteins (phloem proteins) are present in the lumen of sieve tube elements and play a role in sealing off damaged areas.

5. **Analyzing Option D**:
- **Statement**: "Absence of nucleus at maturity."
- **Evaluation**: This statement is correct. Mature sieve tube elements do not have a nucleus, which is a characteristic of these cells.

6. **Conclusion**:
- Based on the evaluations, the incorrect statement about sieve tube elements is **Option B**: "Perforated end wall become impregnated with lignin."

### Final Answer:
The wrong statement about sieve tube elements is **Option B**.

---