Question

Pressure potential in plasmolysed cell is
a. Positive
b. Zero
c. Negative
d. Remains same

Answer 1

Pressure potential is a component of water potential that can be defined as the hydrostatic pressure exerted on water in a cell. The pressure potential of the cell helps it in maintaining the turgidity of the cell.

Complete answer:
The movement of water and surrounding depends upon the type of solution surrounding the cell. There are three types of solution:
- Isotonic solution- It is the type of solution that has the concentration equal to the concentration of cell sap.
- Hypotonic solution- It is when the concentration of outer solution is higher than the concentration of cell sap.
- Hypertonic solution- It is the solution in which the outer concentration is higher than the concentration of cell sap.

When a plant cell is immersed in a solution which has a higher solute concentration than the cell sap, protoplasm contracts. It leaves a gap between the cell wall and plasma membrane. This shrinkage of protoplasm from the wall is known as plasmolysis.

So, when the cell is kept in a hypertonic solution, it becomes plasmolysed and the positive pressure potential becomes negative. The process of plasmolysis is used to kill the weeds in lawns and tennis courts. It is also used to preserve meat, jelly, etc. as the salting kills bacteria by plasmolysis.

Hence, the correct answer is option (C).

Note: The plasmolysed cell when kept in water or hypotonic solution, it regains its original form and the process is called deplasmolysis. This occurs due to endosmosis of water and it makes the cell turgid.