Based on his studies of purple & green bacteria, who demonstrated that photosynthesis is essentially a light dependent reaction in which hydrogen from a suitable oxidizable compound reduces `CO_(2)` to carbohyrates ?

Options

A. Van Niel
B. Von Sachs
C. Calvin
D. Priestley

Answer

To answer the question regarding who demonstrated that photosynthesis is essentially a light-dependent reaction in which hydrogen from a suitable oxidizable compound reduces carbon dioxide to carbohydrates, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks for the scientist who studied purple and green bacteria and demonstrated that photosynthesis is a light-dependent reaction.

2. **Identifying Key Terms**: The key terms in the question are "purple and green bacteria," "light-dependent reaction," and "reduces CO2 to carbohydrates."

3. **Recalling Relevant Studies**: From the studies of photosynthesis in bacteria, it is known that certain bacteria utilize light to drive the process of photosynthesis, which involves the reduction of carbon dioxide.

4. **Identifying the Scientist**: The scientist who is known for these studies is **Van Niel**. He conducted experiments on purple and green bacteria and concluded that photosynthesis is a light-dependent reaction.

5. **Eliminating Other Options**:
- **Von Sachs** studied the structure of thylakoids and is not directly related to the light-dependent reactions in bacteria.
- **Priestley** is known for his work on oxygen discovery but not specifically for the light-dependent reactions in photosynthesis.

6. **Conclusion**: Based on the studies of purple and green bacteria, the correct answer is **Van Niel**.

### Final Answer:
Van Niel demonstrated that photosynthesis is essentially a light-dependent reaction in which hydrogen from a suitable oxidizable compound reduces carbon dioxide to carbohydrates.

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