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 solve the question regarding which algae undergo sexual reproduction through flagellated and similarly sized gametes, we can follow these steps:

### Step 1: Understand the Types of Sexual Reproduction in Algae
Algae can reproduce sexually in three main ways:
1. **Isogamous**: Gametes are of similar size and can be flagellated or non-flagellated.
2. **Anisogamous**: Gametes are of different sizes, typically one is larger and non-motile while the other is smaller and motile.
3. **Oogamous**: Involves a small motile gamete and a larger non-motile gamete.

### Step 2: Identify the Key Characteristics of Each Alga
- **Ilothrix**: Exhibits isogamous reproduction with flagellated gametes.
- **Spirogyra**: Exhibits isogamous reproduction but with non-flagellated gametes.
- **Eudornia**: Exhibits anisogamous reproduction, with dissimilar sized gametes.
- **Fucus**: Exhibits oogamous reproduction, with a small motile gamete and a large non-motile gamete.

### Step 3: Analyze the Options
From the characteristics:
- **Ilothrix** is the only alga that has flagellated gametes that are also similar in size, thus fitting the criteria of the question.
- **Spirogyra** does not fit because its gametes are non-flagellated.
- **Eudornia** and **Fucus** do not fit because they involve dissimilar gametes.

### Step 4: Conclusion
The correct answer to the question is **Ilothrix**, as it reproduces sexually through flagellated and similarly sized gametes.

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