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 is defined as the free energy of water in a system. It is a measure of the potential energy of water molecules and is influenced by various factors.

2. **Definition of Water Potential**: Water potential (Ψw) can also be described as the chemical potential of water. It is a way to quantify the tendency of water to move from one area to another.

3. **Factors Affecting Water Potential**: Water potential is affected by:
- Concentration of solutes (higher concentration leads to lower water potential)
- Pressure (positive pressure increases water potential)
- Gravity (influence on water potential in tall plants)

4. **Analyzing the Statements**:
- **Statement 1**: "Water potential is expressed as a difference between the potential of a solution in a given state and the potential of the same solution in the standard state."
- This statement is **correct**.
- **Statement 2**: "Water potential is influenced by concentration, pressure, and gravity."
- This statement is **correct**.
- **Statement 3**: "Water potential is measured in terms of pressure."
- This statement is **correct**; it is typically measured in Pascals (Pa).
- **Statement 4**: "Water potential is measured as an absolute quantity."
- This statement is **incorrect**. Water potential is not an absolute quantity; it is comparative and depends on the state of the solution relative to a standard state.

5. **Conclusion**: The incorrect statement regarding water potential is **Statement 4**.

**Final Answer**: The incorrect statement is **Statement 4**.

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