Water potential is measured in terms of

Options

A. Pressure
B. Volume
C. Mass
D. Weight

Answer

**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 reflects the tendency of water to move from one area to another, typically from areas of higher water potential to areas of lower water potential.

2. **Definition of Chemical Potential**: Water potential can be defined as the chemical potential of water molecules. This chemical potential is influenced by the free energy or kinetic energy of the water molecules.

3. **Free Energy Concept**: Water potential can also be described as the difference in free energy between pure water (which has a higher potential) and water in a solution or within a cell (which has a lower potential).

4. **Symbol and Measurement**: Water potential is denoted by the Greek letter psi (Ψ). It is measured in units of pressure, specifically using the unit "bar".

5. **Understanding Units**: One bar is approximately equal to 0.987 atmospheres, which reinforces that water potential is fundamentally a pressure measurement.

6. **Conclusion**: Given the options provided (pressure, volume, mass, weight), the correct answer is that water potential is measured in terms of **pressure**.

**Final Answer**: Water potential is measured in terms of **pressure**.

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