1. EQ: How does diffusion work?
Diffusion and Osmosis
EQ: How does diffusion work?

2. Diffusion
The process by which molecules spread from areas of high concentration to areas of low concentration.
Equilibrium- when molecules are even throughout a space

3. Diffusion
Concentration gradient- a difference between concentrations in a space
Molecules will always move down the concentration gradient toward areas of lesser concentration.
Think of food coloring that spreads out in a glass of water or air freshener sprayed in a room

4. Selective Permeable
Membranes that allow some things through such as water and oxygen by diffusion

5. Osmosis The diffusion of water across a membrane
Water will move in the direction where there is a high concentration of solute (and hence a lower concentration of water)

6. Solutions Solution- all the components are evenly distributed
Solute- the substance being dissolve
Solvent- the substance in which the solute dissolves into

7. Salt solute
Salt is a solute when it is concentrated inside or outside the cell, it will draw the water in its direction.
This is why you get thirsty after eating something salty

8. Types of solutions Isotonic Solutions
If the concentration of solute (salt) is equal on both sides, the water will move back and forth but it won’t have any result on the overall amount of water on either side.
‘Iso’ means same

9. Types of solutions Hypotonic solution ‘Hypo’ means less
In this case there are less solute (salt) molecules outside of the cell and water will move into the cell (where there is a higher concentration of salt)
The cell will gain water and grow larger.
In plant cells, the central vacuoles will fill and the plant becomes rigid. The cell wall prevents the cell from bursting
In animal cells, the cell may be in danger of bursting. Organelles called contractile vacuoles will pump water out of the cell to prevent this

10. Types of solutions Hypertonic solution
‘Hyper’ means more
In this case, there are more solute (salt) molecules outside of the cell, which causes the water to be sucked into that direction
In plant cells, the central vacuole loses water and the cell shrinks, causing wilting.
In animal cells, the cell also shrinks
Drinking salt water is dangerous because it will speed up the process of dehydration
‘Salting the fields’ (a common tactic during war) kills crops and causes food shortages.

11. Passive transport
No energy is required for the molecules to move into or out of the cell.
Both diffusion and osmosis do this

12. Facilitated Diffusion
Since cell membranes have protein channels that makes it easy for certain molecules to cross the membrane
During facilitated diffusion, molecules (ex. Glucose) that can’t diffuse across the lipid’s bilayer on their own, move through the protein channels instead