Mature sieve tube has

Options

A. Nucleus
B. Cytoplasm only
C. Nucleus and cytoplasm
D. None of these

Answer

To answer the question "Mature sieve tube has", let's analyze the characteristics of mature sieve tubes step by step.

### Step-by-Step Solution:

1. **Understanding Sieve Tubes**: Sieve tubes are part of the phloem tissue in flowering plants. They are responsible for the transport of nutrients, particularly sugars, from the leaves to other parts of the plant.

2. **Structure of Sieve Tubes**: Sieve tube elements are specialized cells that form the sieve tubes. They are elongated and connected end to end to form a continuous tube.

3. **Maturity of Sieve Tubes**: As sieve tube elements mature, they undergo significant changes. One of the most important changes is the loss of their nucleus.

4. **Inucleated Condition**: Mature sieve tube elements are described as inucleated, meaning they do not have a true nucleus. This occurs because the nucleus disintegrates during the maturation process.

5. **Presence of Cytoplasm**: Despite the absence of a nucleus, mature sieve tubes still contain cytoplasm. This cytoplasm is essential for the functioning of the sieve tubes, as it helps in the transport of nutrients.

6. **Evaluating the Options**:
- **Option A: Nucleus** - Incorrect, as mature sieve tubes lack a nucleus.
- **Option B: Cytoplasm only** - Correct, as mature sieve tubes contain cytoplasm but no nucleus.
- **Option C: Nucleus and cytoplasm** - Incorrect, as they do not have a nucleus.
- **Option D: None of these** - Incorrect, since option B is correct.

### Conclusion:
The correct answer is that mature sieve tubes have **cytoplasm only**.

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