Question

Which of the following has the highest water potential (Ѱ)?
(a)1 M salt solution
(b)1M sugar solution
(c)1M sugar solution with 2.3 bars pressure applied on it
(d)Distilled water

Answer 1

Hint: It depends on the concentration of water molecules. It always moves in a direction from high water potential region to low water potential region.

Complete step-by-step answer:
The water potential of pure water is zero because in the open container there is no solute and the pressure. It is represented by the Greek letter Psi (Ψ). Upon the addition of solute, the water potential becomes negative. When a solution is surrounded by a rigid cell wall, the movement of water leads to exert pressure on the cell wall. This increased pressure raises the water potential within the cell wall.
The formula of water potential is -
Water potential = pressure potential + solute potential
Solute potential: It is a component of water potential which is also known as osmotic potential. The solute potential is inversely proportional to the amount of solute in a solution, and it decreases as the concentration of solute increases.
Pressure potential: It is an important component of the total water potential within plant cells. When water enters the cell, pressure potential increases because it exerts an outward pressure which is opposed by the structural rigidity of the cell wall.
Additional information:
-Water potential is basically the potential energy of water per unit volume.
-Water potential is essential for the understanding of water movement in plants, soil, and animals.
-It is explained as the tendency of water to move from one area to another due to gravity, mechanical pressure, and osmosis.
So, the correct answer is ‘distilled water’.

Note:
 -The pressure potential of a plant cell is generally positive, it becomes negative when the water is pulled through xylem vessels.
-The value of water potential never becomes positive but has a maximum value of zero.
-Water potential is generally measured in megapascals (MPa).