Question

In a plasmolysed cell :

• A. DPD = 0
• B. DPD = OP
• C. DPD = TP
• D. DPD = WP

Answer 1

Answer:

B. DPD = OP

• DPD (Diffusion Pressure Deficit): This is a measure of the cell's demand for water. It is the difference between the diffusion pressure of pure water and the diffusion pressure of water in a cell. DPD is also expressed by the formula: DPD = OP - TP

• OP (Osmotic Pressure): The pressure needed to prevent the inward flow of water across a semipermeable membrane. It's essentially the measure of solute concentration in the cell sap.

• TP (Turgor Pressure): The outward pressure exerted by the cell contents against the cell wall.

In a fully plasmolysed cell, the cell membrane has pulled away from the cell wall, and the cell has lost all its turgor pressure. Therefore, the turgor pressure (TP) is zero.

Substituting TP = 0 into the DPD formula gives:

DPD = OP - 0

DPD = OP

This means that in a fully plasmolysed state, the cell's demand for water is at its maximum and is solely determined by its osmotic pressure.