Question

A cell placed in hypotonic solution will ______________
A. Shrink
B. Show plasmolysis
C. Swell
D. No change in shape or size

Answer 1

Hint: We are aware of the process of osmosis. This question is with respect to changes that occur within a cell when placed in different kinds of solutions.
For solving this question we have to keep in mind what is hypotonic solution, hypertonic solution, osmosis and what is cell bound by and what is the covering of the cell permeable to then understanding and solving this application based question becomes very easy.

Complete solution:
Let us first have an understanding of cell membrane. Cell membrane made up of lipoprotein is a selectively permeable membrane and allows some molecules like water and gases to move across it freely.
A) HYPOTONIC SOLUTION: it is a type of solution where the amount of solutes is less and amount of solvent is more as compared to that found in the cell. Such a solution has lower osmotic pressure than the solution found in the cell. Examples of such a solution is pure water and tap water and 0.45% normal saline.
B) HYPERTONIC SOLUTION: it is a type of solution where the amount of solutes is more than the amount of water or solvent as compared to the solution found in a cell. Such a solution has higher osmotic pressure than the solution found in a cell. Example of such a solution is 10% dextrose solution (sugar solution with concentration of sugar greater than 5%).
C) OSMOSIS: Process of diffusion of solvent or water from its higher concentration to its lower concentration.
Now, when we place a cell in a hypotonic solution, as the concentration of water is more in the hypotonic solution as compared to that of the cell, water will move inside the cell as the cell membrane is freely permeable to water by the process of endosmosis. Thus, the cell starts to swell and if this further continues, the cell will eventually burst.

Thus the correct answer to this question will be option C.

When the cell is placed in a hypertonic solution, water will move out of the cell by process of exosmosis and the cell will shrink.
Plasmolysis occurs in plant cells. It is the process occurring in the plant cell. When the plant cell is placed in a hypertonic solution, it loses water and this causes a decrease in its turgor pressure. Due to this decrease in the pressure the cell protoplast detaches from the cell wall and forms a space between the cell wall and cell membrane.

Note: For this question to be answered correctly we have to have a clear understanding of what is a hypertonic and hypotonic solution with reference to cell cytoplasm. Also we have to have a clear understanding of the principle of osmosis.
Then we will easily understand that if a cell , especially an animal cell when placed in hypertonic solution it will shrink and when placed in a hypotonic solution it will swell up also when a plant cell that is bound by cell wall when placed in a hypertonic solution will show Plasmolysis.