For the same amount `CO_(2)` fixed `C_(4)` plant, in comparison with a `C_(3)` plants, lose only

Options

A. Half amount of water
B. Double amount of water
C. Equal amount of water
D. None of the above

Answer

### Step-by-Step Solution:

1. **Understanding C3 and C4 Plants**:
- C3 plants utilize the Calvin cycle for photosynthesis, where carbon dioxide (CO2) is fixed into a three-carbon compound.
- C4 plants, on the other hand, have a different pathway that allows them to fix CO2 into a four-carbon compound, which is more efficient in certain conditions.

2. **Efficiency of CO2 Fixation**:
- C4 plants are known for their efficiency in CO2 fixation. They can capture CO2 more effectively than C3 plants, especially in high-temperature and low-water conditions.

3. **Stomatal Behavior**:
- C4 plants can keep their stomata closed for longer periods compared to C3 plants. This is because they have a mechanism that allows them to store CO2 and use it efficiently, reducing the need to open stomata frequently.

4. **Water Loss Comparison**:
- Due to the ability to keep stomata closed longer, C4 plants lose less water through transpiration compared to C3 plants. This is a significant advantage in arid conditions.

5. **Quantifying Water Loss**:
- Research indicates that for the same amount of CO2 fixed, C4 plants lose only about half the amount of water that C3 plants lose. This is a critical factor in their adaptation to dry environments.

6. **Conclusion**:
- Based on the above points, the correct answer to the question is that C4 plants lose only **half the amount of water** compared to C3 plants for the same amount of CO2 fixed.

### Final Answer:
C4 plants lose only half the amount of water compared to C3 plants for the same amount of CO2 fixed.