Tag: movement in and out of the cell

An isotonic solution is a solution, which contains the same concentration of solute as in a cell. If animal and plant cells are kept in isotonic solution then cells will not swell or shrink. Hence, there will not be any change in cells. 

The cell swells up when endosmosis occurs. Endosmosis is a process in which the water molecules move from outside to the inside of the cell through the cell membrane. This occurs when the solution is hypotonic, i.e., the cell has a lower solute concentration than the surrounding medium.

Osmosis is defined as the movement of solvent molecules from a region of their higher concentration (more dilute solution) to a region of their lower concentration (more concentrated solution), through a semipermeable membrane. Hence, the water molecules move into a cell when a cell is placed in a hypotonic medium (resulting in an increase in cell volume) and water moves out of the cell when a cell is placed in a hypertonic medium (resulting in a decrease in cell volume). Thus, the correct answer is option A.

If a cell swells after been placed in a solution, it means water from solution has entered the cell. As water flows from a region of its own higher concentration to a region of lower concentration, we conclude that water is present in higher concentration in the solution as compared to the cell sap. Thus, the solution is hypotonic as compared to cell sap. The process in which water enters the cell is called as endosmosis.

When plant cells are kept in a hypertonic solution (i.e., a solution more concentrated than the plant cell sap) they lose water due to the process of exosmosis. This causes plasmolysis, a process in which protoplasm leaves cell wall and lies shrunk inside the cell. When the cell is kept in hypotonic solution (i.e., a solution far less concentrated than the plant cell sap), it gains water due to the process of endosmosis. The cell now swells and is called as deplasmolyzed cell. If plant cells are kept in isotonic solution, no changes take place. Thus, the correct answer is option B.

Water flows along its own concentration gradient. When a cell is placed in a hypotonic medium it swells due to absorption of water by the process of endosmosis. The endosmotic gain of water makes a cell turgid. When a cell is placed in a hypertonic medium, it loses water due to the process of exosmosis. Exosmotic loss of water results in plasmolysis. Thus, the correct answer is option B.

Hypotonic solution is a solution, which contains lesser solute concentration. In such case, the water molecules move from outside to inside of the cell through cell membrane (semi-permeable membrane). This process is called as endosmosis by which cell gain water. 

Hypotonic solution is a solution, which contains lesser solute concentration. In such a case, the water molecules move from outside to the inside of the cell through the cell membrane. This process is called as endosmosis by which cell gains water and swells up.

In the hypertonic solution, the concentration of solutes is more and the concentration of solvent (water) is less as compared to the cytoplasm of a specific cell. If a cell is placed in such solution plasmolysis will occur due to the movement water from cell to the outer environment.