Question

'A' and 'B' are two adjacent living cells. The cell 'A' has solute potential $\left({\Psi }_s\right)$ of
-9 bars and pressure potential $\left({\Psi }_p\right)$ of 4 bars, whereas cell 'B' has solute potential $\left({\Psi }_s\right)$ of
-8 bars and pressure potential $\left({\Psi }_p\right)$ of 5 bars. What will be the direction of water movement between these cells?

• A. Cell A to Cell B
• B. Cell B to Cell A
• C. Do not move in any direction.
• D. Moves in both the directions.

Answer 1

Answer: (B)

Cell B to Cell A

By convention, the water potential of pure water is given the value zero. Whenever a solute is added to water, there is a decrease in water potential.

Water potential is calculated by using the following formula -

Water potential (Ψ) = pressure potential (Ψp) + solute potential (Ψs).

Thus, water potential for cell A is -5 bars and water potential of cell B is -3 bars.

Water flows from a region of higher water potential to a region of lower water potential. In this case, water will flow from cell B, which has a water potential of - 3 bars to cell A, which has a water potential of - 5 bars.

Thus, the correct answer is option B.