SPM Biology 3 Movement of Substances Across the Plasma Membrane Part 3 3 Types of Solution & the Effects of Different Concentrations of Solution on Cells

The direction of movement of substances across the plasma membrane in the cell depends on the concentration of the solution around it.

There are 3 types of solution:

1. Hypertonic solution = solution with higher concentration of solutes than the cell. (lower water concentration)
2. Hypotonic solution = solution with lower concentration of solutes than the cell. (higher water concentration)
3. Isotonic solution = solution with equal solute concentration.

**osmosis happen when the water diffuse across the membrane from hypotonic solution to hypertonic solution***

Three types of solution

In hypertonic solution, red blood cells undergo crenation (water diffuse out from cell, cell shrivel and die). Plant cells undergo plasmolysis (plant cell loses water and shrivels, cell becomes flaccid, cause plant wilt). 

In hypotonic solution, red blood cells undergo hemolysis (the cell gain water and swell, finally burst because they no cell wall). Plant cells become turgid (vacuole gain water, expands and exerts pressure outwards on the cell wall).

In Isotonic solution, water diffuses into and out of the cell by osmosis at the same rate. The cells maintain their normal shape.

***terms hemolysis & crenation only for red blood cell.

Blood condition in different solutions