Question

A cell is plasmolysed after being kept in a hypertonic solution. What will be present between the cell wall and plasmalemma?
A. Isotonic solution
B. Hypertonic solution
C. Air
D. Hypotonic solution

Answer 1

Hint:-During the process of osmosis there is a movement of water or solvent molecules from a region of higher concentration to a region of lower concentration through a semipermeable membrane till an equilibrium is reached. It is an important phenomenon observed in plants.

Complete answer:
When we place a turgid plant cell in a concentrated or hypertonic solution having more solute e.g. sugar solution, the osmotic pressure will be more which will allow the movement of water from the cell into the solution due to exosmosis. As a result, the vacuoles and the protoplast will shrink and the plasma membrane will pull away from the cell wall. This phenomenon is known as plasmolysis and the cell is known as a plasmolysed cell. In a fully plasmolysed cell, the hypertonic solution like sugar solution will fill in the space formed between the contracted protoplasm and the cell wall. Incipient plasmolysis is the initial stage of plasmolysis. Sometimes, plasmolysed cells even when kept in a hypotonic solution like water, show exosmosis. This is a result of permanent plasmolysis. Such cells fail to regain turgidity and eventually die.
Thus, the right option is B.

Additional Information:-
Turgidity is important for plant cells as it helps a plant to stand straight and upright and provides a mechanical support to the leaves. It is useful during cell division and proper functioning of stomata.

Note:- If a plasmolysed cell is kept in water or hypotonic solution, the water enters the cell sap due to endosmosis and protoplasm assumes its normal shape. The cell regains its turgidity as the plasma membrane also moves towards the cell wall to its normal position. This phenomenon is called deplasmolysis.