Question

Which of the following statements is correct?
A. DPD = OP – WP
B. DPD = OP + WP
C. DPD = WP – OP
D. DPD = TP + OP

Answer 1

DPD is the amount by which the diffusion pressure of a solution is less than that of pure solvent.
Water here is absorbed by the system having higher DPD from the one with lower DPD.

Complete answer:
DPD stands for diffusion pressure deficit.
Diffusion pressure deficit (DPD) is the amount by which the diffusion pressure of water in a solution is less than that of pure water.
DPD is calculated by the formula OP - TP, wherever all the terms are with positive values.
OP stands for osmotic pressure.
The pressure applied on a solution to prevent the inward flow of water through a semipermeable membrane is known as osmotic pressure.
TP stands for turgor pressure.
The pressure that’s exerted by the fluid like water against the cell wall is understood as turgor pressure. It is additionally referred to as hydrostatic pressure.

Hence, option (A) is the correct answer.

Note:-

DPD	Water Potential
Difference between the diffusion pressure of the given solution and pure solvent	Difference between free energy of water molecules in pure water and solution
It is measured in atmospheres	It is measured in bars
Water flows from lower DPD to higher DPD	Water flows from higher water potential to lower water potential
It has positive value	It has negative value
Matric pressure or imbibition force is not taken into account.	Matric pressure or imbibition force is taken into account.

The term “Diffusion pressure deficit” was given by Meyer in 1938.
The term “Water potential” was given by Slatyer and Taylor in 1960.