Question

In a plant cell , the diffusion pressure deficit(DPD) is zero when it is
A) Plasmolysed
B) Turgid
C) Flaccid
D) Incipient

Answer 1

Hint:Diffusion pressure deficit in the amount by which two solutions vary in diffusion pressure. It is defined by the amount by which the diffusion pressure of solvent in a solution is lower than that of pure water.

Complete answer:
Plasmolysis is the shrinking of cytoplasm of a plant cell in response to diffusion of water out of the cell and also into a high salt concentrated solution. During this process the cell membranes pull away from the cell wall. This will not take place in low salt concentrations.

Turgid refers to cells or tissues that are swollen due to the water uptake. Many cell types in numerous different organisms can become turgid due to water uptake. Some cells will split open if they become too turgid. Other cells are intended to be turgid and have a dense and complexly woven extracellular matrix made of special fibrous molecules.

A flaccid plant cell is one in which the plasma membrane is not pushed tightly against the cell wall. This is experiential when the plant cell is placed in an isotonic solution wherein the concentration of solutes in the outside is the same as that in the inside of a plant cell. The plant cell will come into view flaccid, and not swollen or plasmolyzed. The plant cell will lose their flaccidity when it is placed in a hypotonic solution and a hypertonic solution. In a hypotonic solution where the solute concentration of a solution adjoining the cell is lower than that inside the cell, the plant cell tends to allocate more water to move into the cell somewhat than lose it thereby causing the cell to swell and become turgid.

In contrast, a plant cell positioned in a hypertonic solution where the solute concentration of a solution outside the cell is higher than that inside the cell more water leaves than go through the cell and therefore resulting in the plasmolysis of the plant cell.

Diffusion Pressure Deficit is equal to the osmotic pressure which will result in the wall pressure. Wall pressure is the same as Turgor pressure. When a cell is sited in a hypotonic solution water enters the cell. Therefore its osmotic pressure decreases and the turgor pressure level increases. In a completely turgid cell the turgor pressure becomes equivalent to the osmotic pressure. Thus the Diffusion Pressure Deficit becomes zero in a turgid cell.
Thus the correct answer is option (B) turgid.

Note:Turgor pressure is the force in the cell that pushes the plasma membrane against the cell wall. It is also known as hydrostatic pressure.The main difference between a turgid cell and flaccid cell is that a turgid cell contains more water and a flaccid cell lacks water.