The pressure develops in xylem vessels during active transpiration is

Options

A. Negative and push
B. Positive and pull
C. Negative and pull
D. Positive and push

Answer

**Step-by-Step Solution:**

1. **Understanding Xylem Function**: Xylem vessels are responsible for the transport of water and minerals from the roots to the leaves of a plant. This process is crucial for plant hydration and nutrient distribution.

2. **Active Transpiration**: Transpiration is the process through which water evaporates from the surface of leaves, creating a negative pressure within the xylem vessels. This negative pressure helps in pulling water upward against the force of gravity.

3. **Pressure Development**: During active transpiration, the pressure that develops in the xylem vessels is described as negative pressure. This is because the water is being pulled up through the xylem due to the evaporation of water from the leaves, creating a suction effect.

4. **Role of Transpiration Pull**: The main driving force for the movement of water in the xylem is the transpiration pull. As water evaporates from the leaf surfaces, it creates a tension that pulls more water up from the roots through the xylem.

5. **Conclusion**: Therefore, the pressure developed in xylem vessels during active transpiration is negative pressure, which is a result of the transpiration pull.

**Final Answer**: The pressure developed in xylem vessels during active transpiration is negative pressure.

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