Which one of the following shows isogamy with non-flagellated gametes

Options

A. Spirogyra
B. Sargassum
C. Ectocarpus
D. Ulothrix

Answer

To determine which of the given options shows isogamy with non-flagellated gametes, we can follow these steps:

### Step 1: Understand the Definitions
- **Isogamy**: This refers to the fusion of gametes that are morphologically similar. Both gametes look alike.
- **Oogamy**: This involves the fusion of dissimilar gametes, typically a large non-motile female gamete and a smaller motile male gamete.
- **Anisogamy**: This is a type of sexual reproduction where the gametes are of different sizes and/or shapes, but not necessarily flagellated or non-flagellated.

### Step 2: Analyze the Options
The options provided are:
1. **Spirogyra**
2. **Sargassum**
3. **Actocarpus**
4. **Eulothrix**

### Step 3: Identify the Type of Gametes in Each Option
- **Spirogyra**: Exhibits isogamy with non-flagellated gametes (aplanogametes).
- **Sargassum**: Exhibits oogamy, with flagellated male gametes and non-motile female gametes.
- **Actocarpus**: Exhibits anisogamy, with flagellated and non-flagellated gametes.
- **Eulothrix**: Exhibits isogamy, but with flagellated gametes (planogametes).

### Step 4: Determine the Correct Answer
From the analysis:
- **Spirogyra** is the only option that shows isogamy with non-flagellated gametes.

### Conclusion
The correct answer is **Spirogyra**.

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