The part of the plant with highest water potential

Options

A. Root hair
B. Atmosphere
C. Root xylem
D. Mesophyll cell of leaf

Answer

To determine the part of the plant with the highest water potential, we need to understand the concept of water potential and how water moves within a plant.

### Step-by-Step Solution:

1. **Understanding Water Potential**: Water potential is a measure of the potential energy of water in a system compared to pure water. It determines the direction in which water will flow. Water moves from areas of higher water potential to areas of lower water potential.

2. **Identifying Water Sources**: In plants, water is primarily absorbed from the soil through the roots. The soil typically has the highest water potential because it contains a large amount of water.

3. **Water Absorption**: Water enters the plant through the root hairs, which are specialized structures that increase the surface area for absorption. The root hairs take in water from the soil, which has a higher water potential than the root cells.

4. **Movement of Water**: After entering the root hairs, water moves into the root xylem, where it continues to travel upward through the plant to the stem and leaves. However, the water potential in the root xylem is lower than that in the root hairs because some water is already being transported away.

5. **Evaporation from Leaves**: Water eventually reaches the leaves, where it can evaporate into the atmosphere. The water potential in the leaves is lower than that in the root hairs due to transpiration (loss of water vapor).

6. **Conclusion**: Among the options provided (root hair, atmosphere, root, xylem, mesophyll, cell of leaves), the root hairs have the highest water potential because they are directly absorbing water from the soil, which has the highest water potential.

### Final Answer:
The part of the plant with the highest water potential is **root hair**.

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