Types of soultions (Diffusion and Osmosis)

What is a Solution?

A solution is a combination of solute (a solid) that has been dissolved in a solvent (a liquid like water).

-There are three kinds of solutions:

a. isotonic solution - is a solution where the solute concentration of the solution that the cell is in is the same as the solute concentration of the cell's cytoplasm.b. hypotonic solution - is a solution where the solute concentration of the solution that the cell is in is lower than the solute concentration of a cell's cytoplasmc. hypertonic solution - is a solution where the solute concentration of the solution that the cell is in is higher than the solute concentration of a cell's cytoplasm3. What happens when cells are place in different kinds of solutions?

a. Hypertonic solutions
The cells shrink or shrivel due to water leaving the cell. If a cell is placed in a hypertonic solution (higher solute concentration outside the cell) water will leave the cell, the net movement of water is from the inside to the outside of the cell. If blood cells are placed in a salt solution, the cell will shrink or "crenate". When this occurs in a plant cell it is said to plasmolyze.

b. Hypotonic solutions
The cells will swell due to water entering the cell. If a cell is placed in a hypotonic solution (lower solute concentration outside the cell) water will enter the cell, the net movement of water is from the outside to the inside of the cell. If blood cells are placed in a distilled water solution, the will swell or burst. This is called hemolysis in blood cells and lysis in non blood cells. In plant cells it is called turgor pressure because the plant cell wall prevents the cell from bursting.


c. Isotonic solutions
When a cell is placed in a solution where the solute concentration is the same on both sides of the cell membrane, the cell will neither shrink nor swell. 0.9% sodium chloride (salt) is isotonic to blood cells.

http://www.abbysenior.com/biology/transport_across_membranes.htm