Question

Plasmolysis in a plant cell is
A. Shrinkage of vacuoles
B. Shrinkage of nucleus in salt solution
C. Shrinkage of cytoplasm in hypertonic solution
D. Shrinkage of cytoplasm in hypotonic solution

Answer 1

Hint:- All organisms are composed of cells. The cell membrane surrounds a fluid in the cell, called cytoplasm. The cytoplasm is a watery fluid that is present inside the cell and provides the cell with a characteristic framework. It is very essential for a cell because it is the main area of cellular activities in every cell. Water (major solvent) is present in a maximum amount in the cytoplasm and all other elements are its solutes.

Complete Answer:-Along with several other organelles found in a cell, the vacuole is the membrane-bound space found in the cytoplasm. It contains water, sap, excretory products and other materials not useful for the cell. In plants the membrane of the vacuole facilitates the transport of several ions and other materials against a concentration gradient into the vacuole, hence their concentration is significantly higher in the vacuole than in the cytoplasm.
There are three major types of solutions named as- hypertonic, hypotonic and isotonic. The solution is said to be hypertonic if the external solution is more concentrated than that of cytoplasm. The behaviour of a plant cell in a hypertonic solution is called plasmolysis. It can also be defined as the shrinkage of cytoplasm under the influence of a hypertonic solution. Plasmolysis occurs when water moves out of the cell and the cell membrane of a cell shrinks away from its cell wall. Water moves from high water potential (inside the cell) to low water potential (external solution).

Thus the correct answer is Shrinkage of cytoplasm in hypertonic solution, option (C).

Note:- During plasmolysis, water is first lost from the cytoplasm and then from the vacuole. When a cell or tissue is placed in an isotonic solution, there is zero net flow of water towards the inside or outside the cell. When it is placed in a hypotonic solution, water will diffuse into the cell. As a result, the cell becomes turgid. This is called deplasmolysis. Thus plasmolysis is usually a reversible process.