Which of the follwing would happen if the supply of `O_(2)` is decreased to an illuminated wheat plant

Options

A. It photosynthesis would decreases
B. It respiration would increase
C. Its photosynthesis would increase
D. All the physiological process would stop

Answer

To solve the question about the effects of decreased oxygen supply to an illuminated wheat plant, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Photosynthesis and Respiration**:
- Wheat is a C3 plant, which means it primarily uses the C3 pathway for carbon fixation during photosynthesis. This process involves converting carbon dioxide and ribulose bisphosphate into 3-phosphoglycerate.

2. **Role of Oxygen in Photosynthesis**:
- In illuminated conditions, plants primarily undergo photosynthesis, which consumes carbon dioxide and releases oxygen. However, oxygen is also a byproduct of photosynthesis.

3. **Effect of Decreased Oxygen Supply**:
- When the supply of oxygen is decreased, it can lead to an increase in the rate of photosynthesis in C3 plants like wheat. This is because lower oxygen levels can reduce the competition between oxygen and carbon dioxide for the enzyme RuBisCO, which can enhance the fixation of carbon dioxide.

4. **Evaluating the Options**:
- **Option 1**: Photosynthesis would decrease - This is incorrect because, as discussed, the rate of photosynthesis would actually increase.
- **Option 2**: Respiration would increase - This is also incorrect as respiration is not directly correlated with oxygen levels in this context.
- **Option 3**: Photosynthesis would increase - This is correct due to the reasons mentioned above.
- **Option 4**: All physiological processes will stop - This is incorrect as physiological processes would not stop entirely.

5. **Conclusion**:
- The correct answer is that the rate of photosynthesis would increase when the supply of oxygen is decreased in an illuminated wheat plant.

### Final Answer:
The correct option is that the **photosynthesis would increase**.