Question

DPD can be calculated by
A. OP+TP
B. OP=WP
C. OP-TP
D. OP- DPD

Answer 1

Hint:-DPD stands for Diffusion Pressure Deficit. Diffusion pressure is a hypothetical term denoting the potential capability of a molecule or ion to diffuse from regions of high concentration to low concentration. To answer this question, we will first try to understand the different terms and then based on that, we will find the most suitable answer.

Complete answer:
Step 1: Let us first understand the meaning of different terms-
DPD- It is the amount by which diffusion pressure varies between a solution and its pure solvent at a particular temperature and pressure. When solute is added to a solvent system, its DPD increases. Water or other solvent tends to flow from an area of low DPD to high DPD.
OP- It stands for osmotic pressure. It is the minimum pressure that needs to be applied to the solution side to stop the inflow of pure solvent or fluid by osmosis. Higher the concentration of the solution, higher is the osmotic pressure. Water or pure solvent tend to flow from the region of low osmotic pressure to high osmotic pressure.
WP- It stands for wall pressure. It is the counter force exerted by the wall of the cells in response to turgor pressure being exerted on it. And thus, the magnitude of wall pressure depends on both- magnitude of the turgor pressure as well as the nature of the cell wall
TP- It stands for turgor pressure. Turgor pressure is basically the pressure exerted by the fluid components inside a cell resulting in the pressing of the cell membrane against the cell wall. The rigidity of living plant tissues can be attributed to the turgor pressure. Wilting of leaves and flowers is the consequence of loss of turgor due to water loss,etc.
Step 2: From the above discussion, it is quite clear that the net DPD of a cell would result from a fine balance between osmotic pressure and turgor pressure.

Thus, the correct answer is (C).

Note:- Fully turgid cells have 0 DPD as osmotic pressure is equal to turgor pressure. On the other hand, DPD in flaccid cells is equal to OP as the turgor pressure is 0 in flaccid cells. It is noteworthy to mention that a fine balance and combination of all these forces help in maintaining the normal structure and function of the cells as well as facilitate the movement of ions, molecules and solvents across semi-permeable membranes.