Select incorrect statement for water potential / free energy

Options

A. Water potential is expressed as the difference between the potential of a solution in a given state and the potential of the same solution in a standard state.
B. Water potential is influenced by concentration, pressure, and gravity
C. Water potential is measured in terms of pressure
D. Water potential is measured in absolute quantity

Answer

**Step-by-Step Solution:**

1. **Understanding Water Potential:**
- Water potential refers to the free energy of water in a system. It determines the direction of water movement between two systems.

2. **Expression of Water Potential:**
- Water potential is expressed as the difference between the potential of a solution in a given state and the potential of the same solution in a standard state. This means we compare the current state of the solution to a reference state.

3. **Factors Influencing Water Potential:**
- Water potential is influenced by three main factors: concentration, pressure, and gravity. These factors affect how water moves in and out of cells and across membranes.

4. **Measurement of Water Potential:**
- Water potential is measured in terms of pressure, and the unit used for this measurement is Pascal (Pa). It is denoted as Ψ (Psi).

5. **Identifying the Incorrect Statement:**
- Now, we analyze the provided options:
- Option 1: Correct - Water potential is expressed as the difference between the potential of a solution in a given state and the potential of the same solution in a standard state.
- Option 2: Correct - Water potential is influenced by concentration, pressure, and gravity.
- Option 3: Correct - Water potential is measured in terms of pressure (Pascal).
- Option 4: Incorrect - Water potential is not measured in absolute quantity. It is a relative measure, not an absolute one.

6. **Conclusion:**
- The incorrect statement regarding water potential is option 4, which claims that water potential is measured in absolute quantity.

**Final Answer:**
- The incorrect statement for water potential is: **Option 4 - Water potential is measured in absolute quantity.**

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