Spirogyra is green unbranched , filamentous alga.

Answer

**Step-by-Step Solution:**

1. **Introduction to Spirogyra**: Spirogyra is classified as a green, unbranched, filamentous alga. It belongs to the family Zygnemataceae.

2. **Structure of Spirogyra**:
- Spirogyra consists of long, unbranched filaments.
- Each filament is made up of cylindrical cells arranged end to end.

3. **Cellular Components**:
- The cells of Spirogyra have a cell wall, which provides structure and protection.
- Inside the cell, there is cytoplasm, which contains various organelles.

4. **Chloroplasts and Photosynthesis**:
- Spirogyra contains chloroplasts, which are vital for photosynthesis.
- The chloroplasts contain chlorophyll, the green pigment that gives Spirogyra its characteristic green color.

5. **Other Cellular Features**:
- In addition to chloroplasts, Spirogyra cells contain a nucleus, which houses the genetic material.
- There is also a large central vacuole that helps in maintaining turgor pressure within the cell.
- Surrounding the cell wall is a mucilaginous sheath, which provides additional protection and helps in preventing disruptions.

6. **Conclusion**: Based on the above points, the statement that "Spirogyra is a green unbranched filamentous alga" is indeed true, as it accurately describes the characteristics and structure of Spirogyra.

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