The hydrogen donor in bacterial photosyn- thesis is usually

Options

A. `H_2O`
B. `H_2S`
C. `NH_3`
D. `HNO_3`

Answer

**Step-by-Step Solution:**

1. **Understanding Photosynthesis**:
- Photosynthesis is the process by which organisms convert light energy into chemical energy, typically producing glucose and oxygen as byproducts. In plants, this process primarily uses water as the hydrogen donor.

2. **Bacterial Photosynthesis**:
- Some bacteria also perform photosynthesis, but their process differs from that of plants. While plants release oxygen during photosynthesis, certain bacteria do not release oxygen.

3. **Identifying the Hydrogen Donor**:
- In bacterial photosynthesis, the hydrogen donor is not water. Instead, many photosynthetic bacteria utilize hydrogen sulfide (H₂S) as the hydrogen donor.

4. **Byproducts of Bacterial Photosynthesis**:
- When hydrogen sulfide is used, the process results in the release of sulfur rather than oxygen. This is a key distinction between bacterial and plant photosynthesis.

5. **Examples of Photosynthetic Bacteria**:
- An example of a photosynthetic bacterium is cyanobacteria, also known as blue-green algae, which can perform photosynthesis using light energy.

6. **Conclusion**:
- Therefore, the hydrogen donor in bacterial photosynthesis is usually hydrogen sulfide (H₂S).

**Final Answer**: The hydrogen donor in bacterial photosynthesis is usually hydrogen sulfide (H₂S).

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