How can the water potential of a plant cell in equilibrium with pure water be zero when the plant cell contains solute? see section 35.1 ( page 729) . how can the water potential of a plant cell in equilibrium with pure water be zero when the plant cell contains solute? see section 35.1 ( page 729) . the plant cell's cell wall is exerting positive pressure (pressure potential) on the cell, increasing the water potential to zero. the plant cell's cell wall is exerting negative pressure (pressure potential) on the cell, increasing the water potential to zero. the plant cell's cell wall is exerting negative pressure (pressure potential) on the cell, decreasing the water potential to zero. the plant cell's cell wall is exerting positive pressure (pressure potential) on the cell, decreasing the water potential to zero?

Water potential is a measure of the water craving of a biological or chemical compartment. Indeed any substance in aqueous solution (ion or molecule) exerts on the molecules of water a force of attraction. The more concentrated the solution, the stronger the force of attraction, and the less water molecules have the power to leave it. The water potential noted Ψ therefore represents the potential of the water to leave a given compartment. The higher (less negative) it is in a compartment, the more water tends to leave it. Conversely, water tends to enter compartments with low water potential (very negative).

Thus in a plant cell the total hydric potential is equal to zero due to a positive force exerted by the cell wall so that the pure water does not enter the interior of the cell.