numerical: water potential

Question

A cell has solute potential Ψs = -0.7 MPa and pressure potential Ψp = 0.3 MPa. What is its water potential Ψw? (MPa)

RankGuru · Accepted Answer

1. **Water Potential Formula**: The water potential of a plant cell is the sum of its solute potential and pressure potential.
   - $\Psi_w = \Psi_s + \Psi_p$
2. **Identify Given Values**:
   - Solute Potential ($\Psi_s$) = $-0.7 \ MPa$ (always negative or zero).
   - Pressure Potential ($\Psi_p$) = $0.3 \ MPa$ (usually positive in a turgid cell).
3. **Calculation**:
   - $\Psi_w = (-0.7) + (0.3) = \mathbf{-0.4 \ MPa}$.
4. **Conclusion**: The water potential is $-0.4 \ MPa$.

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numerical: water potential

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