Optimum temperature conditions for photosynthesis in `C_(3)` and `C_(4)` plants are respectively

Options

A. `10^(@)C-25^(@)C` and `30^(@)C-45^(@)C`
B. `30^(@)C-45^(@)C` and `10^(@)C-25^(@)C`
C. `0^(@)C-10^(@)C` and `10^(@)C-30^(@)C`
D. `25^(@)C-30^(@)C` and `40^(@)C-50^(@)C`.

Explanation

To determine the optimum temperature conditions for photosynthesis in C3 and C4 plants, we need to analyze the temperature ranges associated with each type of plant.

### Step-by-Step Solution:

1. **Understanding C3 and C4 Plants**:
- C3 plants utilize the Calvin cycle for photosynthesis, where the enzyme RuBisCO plays a crucial role in carbon fixation.
- C4 plants have a different mechanism that involves an additional step before the Calvin cycle, using the enzyme phosphoenolpyruvate carboxylase (PEPCase) for carbon fixation.

2. **Optimum Temperature for C3 Plants**:
- C3 plants generally thrive in cooler temperatures. The optimum temperature range for photosynthesis in C3 plants is typically between **10°C to 25°C**. This is the temperature range where the enzyme RuBisCO operates most efficiently.

3. **Optimum Temperature for C4 Plants**:
- C4 plants, on the other hand, are adapted to warmer environments. Their optimum temperature range for photosynthesis is usually between **30°C to 45°C**. This is because the PEPCase enzyme is more efficient at these higher temperatures.

4. **Comparing the Options**:
- Now, we compare the given options:
- Option 1: 10°C to 25°C (C3) and 30°C to 45°C (C4) - **This matches our findings.**
- Option 2: 30°C to 45°C (C3) and 10°C to 25°C (C4) - **Incorrect.**
- Option 3: 0°C to 10°C (C3) and 10°C to 30°C (C4) - **Incorrect.**
- Option 4: 25°C to 30°C (C3) and 40°C to 50°C (C4) - **Incorrect.**

5. **Conclusion**:
- Based on the analysis, the correct answer is **Option 1: 10°C to 25°C for C3 plants and 30°C to 45°C for C4 plants**.