When a plant cell is placed in a salt solution, osmosis occurs. Osmosis is the movement of water molecules from a region of high water concentration to a region of low water concentration through a semipermeable membrane. In this case, the semipermeable membrane is the cell membrane of the plant cell.

If the salt solution is more concentrated than the cell sap, water will move out of the cell and into the salt solution. This process is called exosmosis. As water leaves the cell, the cell membrane will shrink and pull away from the cell wall. This can cause the cell to become plasmolyzed. Plasmolysis is the collapse of a plant cell due to the loss of water.

If the salt solution is less concentrated than the cell sap, water will move into the cell from the salt solution. This process is called endosmosis. As water enters the cell, the cell membrane will expand and press against the cell wall. This can cause the cell to become turgid. Turgor is the firmness or rigidity of a plant cell due to the pressure of the cell contents against the cell wall.

The concentration of the salt solution relative to the concentration of the cell sap will determine whether exosmosis or endosmosis occurs. If the salt solution is more concentrated, exosmosis will occur and the cell will become plasmolyzed. If the salt solution is less concentrated, endosmosis will occur and the cell will become turgid.