A mesophytic plant growing in well watered soil shows decreased transpiration in the afternoon due to

Options

A. Closure of many stomata
B. Contration of cuticle
C. Less water availability from soil
D. High rate of photosynthesis

Answer

To solve the question regarding why a mesophytic plant growing in well-watered soil shows decreased transpiration in the afternoon, we can follow these steps:

### Step-by-Step Solution:

1. **Understand Mesophytic Plants**:
- Mesophytic plants thrive in environments that are neither too dry nor too wet. They have adapted to moderate water availability.

2. **Identify the Conditions**:
- The question specifies that the plant is growing in well-watered soil, which means there is sufficient water available for the plant.

3. **Consider Transpiration Factors**:
- Transpiration is the process where water vapor is lost from the plant, primarily through small openings called stomata. Several factors can influence transpiration rates, including light intensity, temperature, humidity, and the opening and closing of stomata.

4. **Evaluate the Afternoon Conditions**:
- In the afternoon, light intensity is usually at its peak, which typically promotes photosynthesis and can increase transpiration. However, excessive transpiration can lead to water loss.

5. **Stomatal Behavior**:
- To prevent excessive water loss during high light intensity and heat, many plants will close their stomata in the afternoon. This closure reduces transpiration rates to conserve water.

6. **Eliminate Incorrect Options**:
- The other options provided in the question can be ruled out:
- Less water availability in the soil is incorrect since the soil is well-watered.
- A high rate of photosynthesis would usually lead to increased transpiration, not decreased.
- The cuticle does not contract; it is a protective layer that helps reduce water loss but does not change in size.

7. **Conclusion**:
- The correct reason for decreased transpiration in the afternoon is the closure of many stomata to prevent excessive water loss.

### Final Answer:
The decreased transpiration in the afternoon in a mesophytic plant growing in well-watered soil is due to the **closure of many stomata**.

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