If temperature remains constant then with increasing alttitude, the transpiration will

Options

A. Increases
B. Decreases
C. First increases then decreases
D. Unaffected

Answer

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks about the effect of increasing altitude on transpiration when the temperature remains constant.

2. **Concept of Transpiration**: Transpiration is the process by which water vapor is lost from the plant to the atmosphere, primarily through small openings called stomata.

3. **Effect of Altitude on Atmospheric Pressure**: As altitude increases, atmospheric pressure decreases. This is a critical factor because lower atmospheric pressure can influence the rate of transpiration.

4. **Low Atmospheric Pressure and Transpiration**: At higher altitudes, the lower atmospheric pressure can lead to an increase in the rate of transpiration. This is because the water vapor inside the plant can escape more easily into the atmosphere when the external pressure is lower.

5. **Temperature Consideration**: The question specifies that the temperature remains constant. In general, lower temperatures can reduce the rate of transpiration because cooler air holds less moisture. However, since the temperature is constant in this scenario, we focus solely on the effect of altitude.

6. **Conclusion**: Given that the atmospheric pressure decreases with increasing altitude, and since the temperature is constant, the rate of transpiration will increase due to the low atmospheric pressure. Thus, the correct answer is that transpiration will increase.

### Final Answer:
Transpiration will increase with increasing altitude if the temperature remains constant.

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