The hypothesis that all photosynthetic organic require a source of hydrogen was give by

Options

A. Hill
B. Ruben and kamen
C. Van Niel
D. Emerson and Arnold.

Answer

**Step-by-Step Solution:**

1. **Identify the Hypothesis**: The hypothesis in question is about the source of hydrogen in photosynthesis.

2. **Historical Context**: This hypothesis was proposed by a scientist named Van Niel in the year 1931.

3. **Understanding Photosynthesis**: In photosynthesis, plants convert light energy into chemical energy, using carbon dioxide and water. A key part of this process is the splitting of water (H2O).

4. **Role of Water**: Van Niel's hypothesis states that during photosynthesis, the hydrogen comes from water, not from carbon dioxide. This means that the oxygen released during photosynthesis is derived from water molecules.

5. **Experimental Evidence**: To support his hypothesis, Van Niel studied green sulfur bacteria, which perform photosynthesis using hydrogen sulfide (H2S) instead of water.

6. **Observations from Green Sulfur Bacteria**: When these bacteria were exposed to hydrogen sulfide, they were able to fix carbon dioxide, but instead of releasing oxygen, they released sulfur. This observation reinforced Van Niel's conclusion that the source of hydrogen in photosynthesis is indeed water.

7. **Conclusion**: Therefore, the hypothesis that all photosynthetic organisms require a source of hydrogen was given by Van Niel.

**Final Answer**: The hypothesis that all photosynthetic organisms require a source of hydrogen was given by Van Niel in 1931.

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