1. Diffusion!
Hot
Water
Cold
Water

2. Equilibrium
When the concentration of solute is equal throughout a solution.

3. Concentration Gradient
A concentration gradient is a difference in concentration across a space.
Going “down” the concentration gradient means moving from an area of high concentration to low
High Concentration
Low Concentration
“down” the gradient 

4. How your cells get O2 and get rid of CO2

5. Diffusion: why flatworms are flat !
Since they have no respiratory system, planarians like this have a flattened body plan to allow for fast diffusion of oxygen and carbon dioxide to all their cells.

6. Osmosis: The diffusion of water across a semi-permeable membrane

7. Things always move from areas of higher concentration to lower concentration spontaneously (passively)

8. Effects of Osmosis can be serious for a cell!
Hypotonic
Hypertonic
Isotonic
Water out
Of cell
No net change
Water into cell

9. SOLUTE SUCKS!
Water moves to where there is more solute.

10. Hypo Hypo Hippo

11. How cells cope

12. Osmosis & Plants

13. Plant Cells & Osmosis
Plasmolysis

14. Hypotonic environment
Causes turgor pressure.
Plant is healthy.
Hypertonic environment
Causes wilting.
Plant is unhealthy.
Plasmolysis

15. One Last Time

16. Facilitated Diffusion
Membrane
Proteins
Solutes too big
Or too polar
To diffuse normally

17. Wrap Up / Key Ideas
Diffusion: The movement of solute molecules down a concentration gradient. Small molecules (e.g. H2O, O2, CO2) cross the cell membrane via diffusion
Osmosis: The diffusion of water across a semi-permeable membrane.
Facilitated Diffusion: The diffusion of large and/or polar molecules across the cell membrane through proteins.
Passive Transport: Movement of material into or out of a cell without the use of energy by the cell.
Concentration gradient: A difference in solute concentration across a space.

18. You Need Energy to Go Up a Concentration Gradient!
Fresh water out
Salt water at high pressure
Selective membrane prevents large solutes and ions from passing through.
They become MORE concentrated

19. Passive Transport Definition: Type 1 Type 3 Type 2 DIFFUSION OSMOSIS
The process of substances passing through the cell membrane WITHOUT ANY INPUT OF ENERGY BY THE CELL.
Passive Transport
Type 1
Type 3
Type 2
DIFFUSION
OSMOSIS
FACILITATED
DIFFUSION
Definition:
Solute molecules move from an area of high concentra-tion to an area of low conc. Powered by the random motion of molecules.
Key Term:
Equilibrium
Definition:
Cell uses carrier proteins in membrane to allow the diffusion of molecules that can’t pass through membrane alone.
Hypertonic:
Solute conc. Bigr
outside. H2O out
Definition:
Diffusion of water from an area of high H2O conc. (low solute conc.) to low (high solute conc.)
Required for
Ions
(charged
molecules)
Isotonic:
Solute conc. =
Inside & out.
No net H2O
change.
And
Hypotonic:
Solute conc. Lower outside.
H2O in. Hypo-Hippo
Large
Molecules