1. Cell Processes
Diffusion & Osmosis

2. How Substances Move into and out of a Cell.
1. Diffusion
2. Osmosis
3. Active Transport
Passive Transport

3. Diffusion
The process by which molecules move from an area of higher concentration to an area of lower concentration.
Concentration of a substance is the amount of the substance in a given volume.

4. What causes Diffusion? Molecules are always moving.
They bump into each other.
The more molecules there are in an area, the more collisions there will be.
Collisions cause molecules to push away from one another and spread apart.
Eventually they spread evenly throughout the area.

5. Example of Diffusion (osmosis)
There is a higher concentration of oxygen molecules outside the cell than inside the cell
The concentration of oxygen molecules is the same outside and inside the cell

6. Osmosis
Osmosis is the diffusion of water molecules through a selectively permeable membrane. (cell membrane)
Very important! Cells cannot function properly without adequate water.

7. Hypotonic- solution with more water and less stuff (solute) dissolved in it. Has more H2O (solvent) in it
Hypertonic- a solution with less H2O (solvent) and more stuff (solute) dissolved in it.
Isotonic- a solution that has the same amount of H2O as what is on the other side of the membrane.

8. Consequences of Osmosis on Cells.
During osmosis water moves into the cell
Concentration of water inside the cell is the same as outside
Water moves out of the cell during osmosis