Algae reproducing by both isogamy and anisogamy is

Options

A. Fucus.
B. Volvox.
C. Sprirogyra
D. None of these

Answer

To solve the question of which algae reproduce by both isogamy and anisogamy, we need to first understand the definitions of these terms and then analyze the options provided.

### Step-by-Step Solution:

1. **Define Isogamy and Anisogamy**:
- **Isogamy**: This is a type of sexual reproduction where the gametes (reproductive cells) are morphologically similar. This means that the male and female gametes are indistinguishable from one another.
- **Anisogamy**: In this type of reproduction, the gametes are structurally different. The male and female gametes can be distinguished from each other, typically with one being smaller (male) and the other larger (female).

2. **Analyze the Options**:
- **Option A: Fucus**: Fucus is known to reproduce through anisogamy, where the gametes are distinguishable.
- **Option B: Volvox**: Volvox also reproduces through anisogamy, where the male and female gametes are different.
- **Option C: Spirogyra**: Spirogyra is known for isogamy, where the gametes are similar in structure.
- **Option D: None of these**: This option suggests that none of the listed algae reproduce by both methods.

3. **Conclusion**:
- After analyzing the options, we find that:
- Fucus and Volvox reproduce by anisogamy.
- Spirogyra reproduces by isogamy.
- Therefore, none of the options A, B, or C reproduce by both isogamy and anisogamy.

Thus, the correct answer is **D: None of these**.