Which of the following statements is not true for class phaeophyceae?

Options

A. Vegetative reproduction takes place by fragmentation
B. The protoplast contains, in addition to plastids, a centrally located vacuole and nucleus.
C. Sexual reproduction may be isogamous, anisogamous or oogamous.
D. Asexual reproductive by uniflagellate zoospores

Answer

To solve the question regarding which statement is not true for the class Phaeophyceae (brown algae), we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Class Phaeophyceae**:
- Phaeophyceae is commonly known as brown algae. It is one of the three classes of algae, alongside Chlorophyceae (green algae) and Rhodophyceae (red algae).

2. **Review the Characteristics of Phaeophyceae**:
- Brown algae contain chlorophyll A and C.
- The pigment that gives them their characteristic brown color is fucoxanthin.
- They can reproduce both vegetatively and sexually.

3. **Examine Each Statement**:
- **Statement 1**: "Vegetative reproduction takes place by fragmentation."
- This statement is true. Brown algae can reproduce vegetatively through fragmentation.

- **Statement 2**: "The protoplast contains in addition to plastids a centrally located vacuole and nucleus."
- This statement is also true. Brown algae have plastids, a vacuole, and a nucleus in their protoplast.

- **Statement 3**: "Sexual reproduction may be isogamous, anisogamous, and oogamous."
- This statement is true. Brown algae can reproduce sexually in all three forms: isogamous (similar gametes), anisogamous (different-sized gametes), and oogamous (one large non-motile gamete and one small motile gamete).

- **Statement 4**: "Asexual reproduction by uniflagellated zoospores."
- This statement is false. Brown algae reproduce asexually using biflagellated zoospores, not uniflagellated.

4. **Conclusion**:
- The statement that is not true for Phaeophyceae is the fourth one: "Asexual reproduction by uniflagellated zoospores."

### Final Answer:
The statement that is not true for class Phaeophyceae is: "Asexual reproduction by uniflagellated zoospores."