Unicellular green alga with only one chloroplast is

Options

A. Spirogyra
B. Ulothrix
C. Ulva
D. Chlamydomonas

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks for a unicellular green alga that possesses only one chloroplast. We need to identify which of the given options fits this description.

2. **Analyzing the Options**:
- **Option 1: Spirogyra**: This is a filamentous green alga, which is multicellular and contains multiple ribbon-shaped chloroplasts (typically 2 to 10). Therefore, it does not meet the criteria of being unicellular with one chloroplast.

- **Option 2: Yulotrix**: This is also a multicellular alga and contains more than two chloroplasts. Hence, it is not the correct answer as it does not fulfill the unicellular requirement.

- **Option 3: Ulva**: Ulva is known as sea lettuce and is a multicellular alga. Although each cell may have one chloroplast, it does not qualify as unicellular. Thus, this option is incorrect.

- **Option 4: Chlamydomonas**: This is a unicellular green alga that typically contains only one chloroplast. It fits both criteria of being unicellular and having a single chloroplast.

3. **Conclusion**: Based on the analysis of the options, the correct answer is **Chlamydomonas**, as it is the only unicellular green alga with one chloroplast.

**Final Answer**: Chlamydomonas

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