Leaves which appear wilted in the day time recover at night because :

Options

A. Light is essential for photo synthesis
B. The stomata close down, temperature decrease, transpiration is reduced and the plant is able to absorb more water from the soil
C. Respiration and translocation of organic substance both increases
D. The plant is sleeping because of dark conditions

Answer

**Step-by-Step Solution:**

1. **Understanding Wilting**:
- Wilting in leaves refers to the loss of turgor pressure, causing the leaves to droop or appear withered. This is often due to a lack of water in the plant cells.

2. **Causes of Wilting**:
- The primary cause of wilting is plasmolysis, which occurs when plant cells lose water and shrink. This typically happens during the day when transpiration rates are high.

3. **Transpiration During Daytime**:
- During the day, the temperature is usually higher, leading to an increased rate of transpiration (the process of water vapor loss from plant surfaces). This means that plants lose more water than they can absorb from the soil.

4. **Water Absorption**:
- When transpiration exceeds water absorption, the plant cells lose water, leading to wilting. The roots may not be able to take up enough water to compensate for the loss.

5. **Recovery at Night**:
- At night, the temperature drops, which reduces the rate of transpiration. With less water being lost, the plant can recover. The stomata (tiny openings on leaves) may also close during the night, further reducing water loss.

6. **Conclusion**:
- Therefore, the reason leaves that appear wilted during the day recover at night is that the rate of transpiration decreases due to lower temperatures and the closing of stomata, allowing the plant to absorb more water from the soil than it loses.

**Final Answer**: Leaves which appear wilted in the daytime recover at night because the stomata close, reducing transpiration and allowing the plant to absorb more water from the soil.

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