Question

The value for Ψ in root tissue was found to be -3.3 bars. If you take the root tissue and place it in a 0.1 M solution of sucrose at 20 °C in an open beaker, what is the Ψ of the solution, and in which direction would the net flow of water be?

Answer 1

The water potential of a 0.1 M sucrose solution is -2.4 bars, and since the root tissue has a lower water potential at -3.3 bars, water will move from the sucrose solution into the root tissue.

Step-by-step explanation:

The solute potential (ψs) of a 0.1 M sucrose solution can be calculated using the van 't Hoff equation: ψ = -MiRT. Assuming a van 't Hoff factor (i) of 1 (since sucrose does not ionize in solution), the gas constant (R) as 0.0831 liter bars per mole per Kelvin, and the temperature (T) in Kelvin (293 K for 20°C), the solute potential equates to approximately -2.4 bars. Therefore, the water potential (ψ) of the sucrose solution is -2.4 bars.

Given that the value for ψ in root tissue is -3.3 bars and the value for ψ in the sucrose solution is -2.4 bars, water will move from the sucrose solution to the root tissue. This is because water moves from an area of higher water potential to an area of lower water potential to reach equilibrium.