1. Diffusion
Movement of molecules from an area of high concentration to an area of lower concentration (down a concentration gradient).
Continues until equilibrium is reached.

2. Concentration Gradient
100% - high
0 % - lower

3. Diffusion Affected by: Size of molecules Size of pores in a membrane
Temperature
Stirring

4. Cell Membranes are Semipermeable
Cell membranes allow some molecules pass through and not others.
Small molecules pass through – ex: water and oxygen
Large molecules can’t pass through – ex: proteins and complex carbohydrates

5. How long does diffusion continue?
Until equilibrium is reached:
This means there will be an equal distribution of molecules throughout the space – this is why odors smell strong at first, then seem to disappear

6. Osmosis
Osmosis is the diffusion of water across a selectively permeable membrane
Cytoplasm is a solution of water and solutes (stuff dissolved in the water).
Water moves into and out of cells because of the different concentrations of the solutes.

7. Osmosis A simple rule to remember is:
Osmosis
A simple rule to remember is: 
Salt is a solute, when it is concentrated inside or outside the cell, it will draw the water in its direction. This is also why you get thirsty after eating something salty.

8. Types of Solutions- Isotonic
In an isotonic solution the concentration of solute is the same
Both inside and outside of the cell. No net movement of water.

9. Types of Solutions- hypotonic
The word "HYPO" means less, in this case there are less solute (salt) molecules outside the cell
The cell will gain water and grow larger.
In plant cells, the central vacuoles will fill and the plant becomes turgid.
In animal cells, the cell may be in danger of bursting or lysing

10. Hypotonic

11. Types of Solutions- Hypertonic
The word "HYPER" means more, in this case there are more solute (salt) molecules outside the cell, which causes the water to be sucked in that direction.
In plant cells, the central vacuole loses water and the cells shrink, causing wilting.
In animal cells, the cells also shrink.
Called plasmolysis in both plant and animal cells.