Question

Movement of water occurs from

• A. higher DPD to lower DPD
• B. higher solute concentrations to lower solute concentration
• C. lower 𝚿w to higher 𝚿w
• D. None of these

Answer 1

The correct option is D None of these

Kinetic energy (KE) or free energy (FE/ energy available to molecules) of water is its water potential (𝚿w). Pure water has highest KE/𝚿w whose value=0.

When a solute is dissolved in water, some water molecules bind to the solute molecules. This decreases the number of free water molecules. Also, bound molecules cannot move about as freely as free molecules. This decreases the 𝚿w. 𝚿w of solution<𝚿w of pure water.

When the molecules undergo diffusion from a region of their higher concentration to a region of their lower concentration (along a concentration gradient), the diffusing molecules tend to exert a pressure known as diffusion pressure.

The lowering in diffusion pressure of water in solution over its pure state due to the presence of solutes and opposing forces in it is known as diffusion pressure deficit (DPD).

DPD is directly proportional to the concentration of solutes added. DPD is less when less solute is added, allowing more 𝚿w and vice versa.
So, water moves from lower DPD to higher DPD, lower concentration (solute concentration) to higher concentration (solute concentration) and higher 𝚿w to lower 𝚿w.