In brown algae, the motile stages have flagella inserted

Options

A. Anteriorly
B. Laterally
C. Posteriorly
D. Both A and B.

Answer

**Step-by-Step Solution:**

1. **Identify the Organism**: The question refers to brown algae, which belong to the group known as Phaeophyta (or Cryophyta).

2. **Understand the Structure**: Brown algae are characterized by their pigments, primarily chlorophyll A, chlorophyll C, and the accessory pigment fucoxanthin.

3. **Focus on Motile Stages**: The question specifically asks about the motile stages of brown algae. In many algae, motility is facilitated by flagella.

4. **Determine Flagella Insertion**: In brown algae, the flagella are inserted laterally. This means that the flagella are attached to the sides of the motile cells, which aids in movement.

5. **Evaluate the Options**:
- Option A (anteriorly) is incorrect because the flagella are not located at the front.
- Option B (laterally) is correct as established.
- Option C (posteriorly) is incorrect because the flagella are not located at the back.
- Option D (both A and B) is incorrect since A is wrong.

6. **Conclusion**: The correct answer is that in brown algae, the motile stages have flagella inserted laterally.

**Final Answer**: Laterally.

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