Question

Cell $A$ has osmotic potential of - $18$ bars and pressure potential of $8$ bars, whereas, cell $B$ has osmotic potential of - $14$ bars and pressure potential $2$ bars. The direction of flow of water will be

• A. from cell B to cell A
• B. from cell A to cell B
• C. no flow of water
• D. in both the directions

Answer 1

Answer: (B)

The water potential $(\psi )$ is equal to osmotic potential $\left({\psi }_s\right)+$ presure potential $\left({\psi }_p\right)$. Osmotic potential is always in negative value. The water potential is the chemical potential of water, which is equivalent to DPD with negative sign.
Therefore, water potential $\left({\psi }_A\right)$ of cell
$A={\psi }_A={\psi }_s+{\psi }_p=-18+8=-10$
water potential of cell
$B\left({\psi }_B\right)={\psi }_B={\psi }_s+{\psi }_p=-14+2=-12$
Since, water moves from higher water potential to lower potential, the flow of water will be from cell $A$ (-$10$ bars) to cell $B$ (- $12$ bars).