In which of the following algae sexual reproduction takes place through flagellate and similar sized gametes?

Options

A. Ulothrix
B. Spirogyra
C. Fucus
D. Eudorina

Answer

To determine which algae undergo sexual reproduction through flagellate and similar sized gametes, we can analyze the options provided:

1. **Eulothrix**:
- Eulothrix is a green algae that reproduces sexually by forming flagellated gametes that are morphologically similar in size. This characteristic makes Eulothrix a suitable candidate for the question.

2. **Spirogyra**:
- Spirogyra reproduces sexually through a process called conjugation. The gametes produced are non-flagellated and similar in size. Therefore, this option does not fit the criteria of having flagellated gametes.

3. **Fucus**:
- Fucus is a brown algae that exhibits oogamous reproduction, meaning it has gametes of different sizes. The female gamete is large and non-motile, while the male gamete is smaller and motile. This dissimilarity in size disqualifies Fucus from being the correct answer.

4. **Eudorina**:
- Eudorina is known for its isogamous reproduction, where the gametes are similar in size but are not flagellated. This also does not meet the requirement of flagellated gametes.

Based on the analysis, the only algae that reproduces sexually through flagellate and similar sized gametes is **Eulothrix**.

**Final Answer**: Eulothrix