Which of the organism show no evolution of Oxygen during photosynthesis

Options

A. Chlorobium
B. Chromatium
C. Oscillatoria
D. Rhodospirillum

Answer

To determine which organism shows no evolution of oxygen during photosynthesis, we need to understand the two types of photosynthesis: oxygenic and anoxygenic.

### Step-by-Step Solution:

1. **Understand Photosynthesis Types**:
- Photosynthesis can be classified into two types:
- **Oxygenic Photosynthesis**: This process produces oxygen as a byproduct. It typically occurs in plants, algae, and cyanobacteria, where water (H2O) is used as the electron donor.
- **Anoxygenic Photosynthesis**: This process does not produce oxygen. Instead, other substances like hydrogen sulfide (H2S) are used as electron donors.

2. **Identify Organisms**:
- Higher plants, algae, diatoms, and dinoflagellates perform oxygenic photosynthesis.
- Certain bacteria, such as purple sulfur bacteria (e.g., Chromatium) and green sulfur bacteria (e.g., Chlorobium), perform anoxygenic photosynthesis.

3. **Focus on the Question**:
- The question asks specifically for an organism that does not evolve oxygen during photosynthesis.

4. **Select the Correct Organism**:
- Among the options, **Chlorobium** is a green sulfur bacterium that uses H2S instead of water, thus it does not produce oxygen during photosynthesis.
- Other options like Chromatium, Oscillatoria, and Rhodospirillium are known to perform oxygenic photosynthesis, as they are related to cyanobacteria.

5. **Conclusion**:
- The correct answer is **Chlorobium**, as it is the organism that shows no evolution of oxygen during photosynthesis.

### Final Answer:
**Chlorobium** (Option 1) shows no evolution of oxygen during photosynthesis.

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