Question

In a fully turgid cell, the value of DPD, OP and TP should be
A. DPD = \[10atm\], OP =\[15atm\], TP =\[5atm\]
B. DPD = \[5atm\], OP = \[12atm\], TP =\[7atm\]
C. DPD = \[2atm\], OP = \[7atm\], TP =\[5atm\]
D. DPD = \[0atm\], OP = \[15atm\], TP= \[15atm\]

Answer 1

Hint: DPD, OP, and TP are namely, Diffusion Pressure Deficit, Osmotic Pressure, and Turgor pressure respectively. Osmotic Pressure and Turgor Pressure can also be referred to as solute potential and pressure potential.

Complete answer:
- Osmotic Pressure: It is the hydrostatic pressure developed in a solution when separated from a pure solvent with the help of a semipermeable membrane in a vessel.
- Turgor Pressure: It is the pressure build-up against the wall when the cells are placed in a hypotonic solution in which the water tends to diffuse in, resulting in swelling up of the cell.
- Liquids have their respective diffusion pressures with water having the maximum diffusion pressure. A solution containing a solute will have a lesser diffusion pressure as compared to a pure solvent. Due to this, there is always a difference between the diffusion pressure of the solvent and the diffusion pressure of the solute.
- Diffusion Pressure Deficit: It is the water absorption capacity of a solution. It can also be defined as the difference between the diffusion pressure of a solution and a pure solvent when both are subjected to the same atmospheric pressure.
- Diffusion pressure Deficit = Osmotic pressure – Turgor pressure
DPD = OP – TP
- In a fully turgid cell, the increasing turgor pressure is equal to the decreasing osmotic pressure, therefore diffusion pressure deficit becomes 0.

Hence, the correct answer is option (D).

Note:
- When the cell is flaccid, it’s Diffusion Pressure Deficit = Osmotic Pressure
- The entry of water into the cell causes the development of turgor pressure.
- The term Diffusion Pressure Deficit was given by B S. Meyer.
- Diffusion Pressure Deficit was termed as Suction Pressure by Renner.
- The value of Diffusion Pressure Deficit is always positive for a cell.
- Pure water has maximum diffusion pressure.