Question

The value of water potential ${\Psi }_w$ for a solution at atmospheric pressure is :-

• A. ${\Psi }_w={\Psi }_s$
• B. ${\Psi }_w=zero$
• C. ${\Psi }_w=-{\Psi }_s$
• D. ${\Psi }_w={\Psi }_s+{\Psi }_p$

Answer 1

The correct option is A ${\Psi }_w={\Psi }_s$

The value of water potential ${\Psi }_w$ for a solution at atmospheric pressure is equal to the solute potential i.e., ${\Psi }_w={\Psi }_s$. This happens because, at atmospheric pressure, there is no hydrostatic pressure on water in the cell. As a result, the value of Pressure potential is effectively zero. Subsequently making water potential equal to solute potential. As we know, Water potential = solute potential + pressure potential, but pressure potential is equal to zero. Hence, ${\Psi }_w={\Psi }_s$.

So, the correct option is '${\Psi }_w={\Psi }_s$'.