Inhibition of photosynthesis in high concentration of oxygen is mainly due to

Options

A. distribution of RuBP carboxylase
B. inactivation of RuBP carboxylase
C. non-synthesis of RuBP carboxylase
D. RuBP carboxylase acting as oxygenase

Answer

**Step-by-Step Solution:**

1. **Understanding Photosynthesis**: Photosynthesis is the process by which green plants, algae, and some bacteria convert light energy into chemical energy, primarily in the form of glucose, using carbon dioxide and water. Oxygen is released as a byproduct.

2. **Role of Rubisco**: The enzyme ribulose-1,5-bisphosphate carboxylase/oxygenase (commonly known as Rubisco) is crucial in the photosynthetic process. It catalyzes the first major step of carbon fixation in the Calvin cycle.

3. **High Oxygen Concentration**: In conditions where there is a high concentration of oxygen and a low concentration of carbon dioxide, Rubisco can react with oxygen instead of carbon dioxide. This reaction leads to a process known as photorespiration.

4. **Photorespiration**: During photorespiration, Rubisco catalyzes the reaction of ribulose bisphosphate (RuBP) with oxygen instead of carbon dioxide. This results in the production of a two-carbon compound (glycolate) and the release of carbon dioxide, which is counterproductive to photosynthesis.

5. **Inhibition of Photosynthesis**: The competition between oxygen and carbon dioxide for Rubisco's active site leads to a decrease in the efficiency of photosynthesis. Therefore, high levels of oxygen inhibit the process of photosynthesis primarily through the action of Rubisco acting as an oxygenase instead of a carboxylase.

6. **Conclusion**: The inhibition of photosynthesis in high concentrations of oxygen is mainly due to the action of Rubisco, which acts as an oxygenase under such conditions, leading to photorespiration.

**Final Answer**: The inhibition of photosynthesis in high concentration of oxygen is mainly due to Rubisco acting as an oxygenase.

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