Question

The turgor pressure of a turgid cell is equal and opposite to
(a) Root pressure
(b) Wall pressure
(c) Diffusion pressure
(d) All of the above

Answer 1

A cell is said to be turgid when it has a maximum amount of water it in and cannot take in any more water. A cell becomes turgid when it is placed in a hypotonic solution i.e. water flows from that solution into the cell until they both have equal water potential.

Complete Answer:
Turgor pressure is defined as the pressure which is equal and opposite to wall pressure that is applied on the walls of a turgid cell. When a cell is placed in a hypotonic solution, water keeps entering into the cell until the pressure starts developing on the walls of the plant cell. This pressure is known as turgor pressure and water keeps entering the cell until the turgor pressure becomes equal to the osmotic pressure of the cell. Turgor pressure along with osmotic pressure affects the diffusion pressure deficit.

Additional information: Let us look at the equation D.P.D. = O.P. - W.P./T.P.; Where D.P.D. stands for diffusion pressure deficit
O.P. is the osmotic pressure
And W.P./T.P. is wall or turgor pressure.
The diffusion pressure deficit is defined as the amount by which there is a deficit in the tendency of a solution to diffuse as compared to a pure water solution. The DPD is zero for a fully turgid cell as osmotic pressure OP is equal to turgor pressure (TP).
Osmotic pressure is the amount of pressure that is required to stop the tendency of pure water to flow inside a solution due to its osmotic concentration.
Wall pressure is equal and opposite to turgor pressure and is defined as the pressure applied on the walls of the cell.
So, the correct option is ‘(b) Wall pressure’.

Note: The turgor pressure of a plasmolyzed cell is zero thus, DPD is equal to OP. Water potential is also used in place of diffusion pressure deficit. Root pressure is defined as the positive pressure developed in the cells of the root due to excess water and electrolyte intake.