Bacterial photosynthesis is unique because

Options

A. it can take place without photosynthetic pigment
B. it can take place without water
C. it can take place without `CO_2`
D. it can take place without light

Answer

**Step-by-Step Solution:**

1. **Understanding Bacterial Photosynthesis**: Begin by recognizing that bacterial photosynthesis is a process through which certain bacteria convert light energy into chemical energy. This process is distinct from the photosynthesis seen in plants.

2. **Identifying the Unique Features**: The uniqueness of bacterial photosynthesis lies in its ability to perform photosynthesis without some of the typical components required in plant photosynthesis.

3. **Analyzing the Options**:
- **Option 1**: States that photosynthesis can occur without photosynthetic pigments. This is incorrect because photosynthetic pigments are essential for capturing light energy.
- **Option 2**: Claims that photosynthesis can occur without water. This is a key feature of bacterial photosynthesis, as some bacteria use hydrogen sulfide (H2S) instead of water as a hydrogen donor.
- **Option 3**: Suggests that photosynthesis can occur in the absence of carbon dioxide. This is not accurate as carbon dioxide is typically required for photosynthesis.
- **Option 4**: States that photosynthesis can occur without light. This is also incorrect since light is necessary for the process.

4. **Focusing on the Correct Option**: Based on the analysis, option 2 is correct because bacterial photosynthesis can occur without water, utilizing other compounds like H2S instead.

5. **Conclusion**: Therefore, the unique aspect of bacterial photosynthesis is that it can take place without water, which is not the case in plant photosynthesis.

**Final Answer**: Bacterial photosynthesis is unique because it can occur without water.

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