Which of the following statements about Phaeophyceae in incorrect? a. Vegetative reproduction occurs fragmentation. b. Asexual reproduction is by biflagellate pear-shaped zoospores. c. In sexual reproduction, gametes are pyriform and bear 2 laterally attached flagella. d. none of these

Options

A. Vegetative reproduction occurs fragmentation.
B. Asexual reproduction is by biflagellate pear-shaped zoospores.
C. In sexual reproduction, gametes are pyriform and bear 2 laterally attached flagella.
D. Nono of these.

Answer

To determine which statement about Phaeophyceae (brown algae) is incorrect, we will analyze each option step by step.

### Step-by-Step Solution:

1. **Understanding Phaeophyceae**:
- Phaeophyceae, commonly known as brown algae, are a group of algae characterized by their brown color due to the presence of the pigment fucoxanthin.

2. **Analyzing Option A**:
- **Statement**: "Vegetative reproduction occurs by fragmentation."
- **Evaluation**: This statement is correct. In Phaeophyceae, vegetative reproduction does occur through fragmentation, where parts of the thallus break off and develop into new individuals.

3. **Analyzing Option B**:
- **Statement**: "Asexual reproduction is by biflagellate pear-shaped zoospores."
- **Evaluation**: This statement is also correct. Asexual reproduction in brown algae occurs through the formation of zoospores, which are biflagellate (having two flagella) and typically have a pear shape (pyriform).

4. **Analyzing Option C**:
- **Statement**: "In sexual reproduction, gametes are pyriform and bear 2 laterally attached flagella."
- **Evaluation**: This statement is correct as well. In the sexual reproduction of brown algae, the gametes are indeed pyriform and possess two laterally attached flagella.

5. **Analyzing Option D**:
- **Statement**: "None of these."
- **Evaluation**: Since all the previous statements (A, B, and C) have been evaluated and found to be correct, this option indicates that there are no incorrect statements among the provided options.

### Conclusion:
- After evaluating all the options, we find that all statements A, B, and C are correct. Therefore, the answer is **option D: none of these**.