1. Osmosis 67% sugar solution 83% sugar solution
During diffusion, what moves?
Explain what will happen to the cells below if diffusion occurs
67% sugar solution
83% sugar solution

2. Objectives By the end of the period, all SWBAT…
Predict the movement of water using osmosis

3. Osmosis! Key Point #1: Osmosis is the diffusion of water But… why?!?!
Osmosis is a special kind of diffusion
The solvent (water) moves, instead of the solute (stuff)
But… why?!?!

4. Blue=water, Green=solute
Want to equalize concentration. According to diffusion (what we learned yesterday), the green solute will move from left to right to increase concentration. But it can’t. So instead, water will move right to left to dilute the solution.

5. Blue=water, Green=solute

6. So What?
Key Point #2: When cells are placed in hypertonic or hypotonic solutions, they change in volume
Hyper- = high
Hypo- = low
Iso- = same

7. Outside Cell Inside Cell 70% water 50% water Hypertonic Solution
Make them figure this out. Ask: what will happen under osmosis? (Water will leave cell.) Then, follow-up: if water leaves the cell, what will happen to the volume of the cell? (It will shrivel up!)

8. Outside Cell Inside Cell 70% water 50% water Water Water Water
Hypertonic Solution
Outside Cell
Inside Cell
Water
Water
70% water
50% water
Water

9. Inside Cell 60% water 60% water Outside Cell Water Water Water
Hypertonic Solution
Inside Cell
Water
Water
60% water
60% water
Water
Outside Cell

10. Outside Cell Inside Cell 22% water 40% water Hypotonic Solution
Make them figure this out. Ask: what will happen under osmosis? (Water will enter cell.) Then, follow-up: if water enters the cell, what will happen to the volume of the cell? (It will swell!)

11. Outside Cell Inside Cell 22% water 40% water Water Water Water
Hypotonic Solution
Inside Cell
Water
Water
22% water
40% water
Water

12. Inside Cell Outside Cell 30% water 30% water Water Water Water
Hypotonic Solution
Inside Cell
30% water
Water
Water
Water
30% water

13. Inside Cell 90% water 90% water Outside Cell Isotonic Solution
Make them figure this out. Ask: what will happen under osmosis? (Nothing.) Then, follow-up: nothing happens, what will happen to the volume of the cell? (Nothing!)
Outside Cell

14. Red blood cells in action
rbc.html

15. Pull into groups and get your whiteboards, please!

16. Outside Cell
Inside Cell
16% water
7% water

17. 88% water
Outside Cell
Inside Cell
54% water

18. Inside Cell
1% water
1% water
CFUs
Outside Cell

19. Hypo, hyper or isotonic?
40% water inside the cell and 10% water outside the cell. The cell membrane is permeable to water.
Is this hypertonic, hypotonic, or isotonic?
How will the water move, according to osmosis?
What will happen to the cell?

20. Hypo, hyper or isotonic?
10% water inside the cell and 90% water outside the cell. The cell membrane is permeable to water.
Is this hypertonic, hypotonic, or isotonic?
How will the water move, according to osmosis?
What will happen to the cell?

21. Hypo, hyper or isotonic?
55% water inside the cell and 55% water outside the cell. The cell membrane is permeable to water.
Is this hypertonic, hypotonic, or isotonic?
How will the water move, according to osmosis?
What will happen to the cell?

22. PAY ATTENTION!!!
20% SUGAR inside the cell and 22% SUGAR outside the cell. The cell membrane is permeable to water.
Make sure they understand that if they’re given sugar, but the membrane is permeable to water, they need to find out the % water. In this case, 80% water inside and 78% water outside  hypertonic  water leaves the cell.

23. Hypo, hyper or isotonic?
20% sugar inside the cell and 22% sugar outside the cell. The cell membrane is permeable to water.
Is this hypertonic, hypotonic, or isotonic?
How will the water move, according to osmosis?
What will happen to the cell?

24. Hypo, hyper or isotonic?
80% sugar inside the cell and 80% sugar outside the cell. The cell membrane is permeable to water.
Is this hypertonic, hypotonic, or isotonic?
How will the water move, according to osmosis?
What will happen to the cell?

25. Hypo, hyper or isotonic?
9% sugar inside the cell and 1% sugar outside the cell. The cell membrane is permeable to water.
Is this hypertonic, hypotonic, or isotonic?
How will the water move, according to osmosis?
What will happen to the cell?

26. We’re getting tricky!
Seawater has a higher concentration of salt than do human body cells. Imagine that poor D’wan is stranded out at sea, and very thirsty. He drinks a bunch of seawater.
What type of solution is seawater (hypertonic, hypotonic, isotonic)?
What will happen to his cells as a result?

27. We’re getting tricky!
Seawater has a lower concentration of water than do human body cells. 
What type of solution is seawater (hypertonic, hypotonic, isotonic)?
What would happen to your cells if you drank seawater?

28. We’re getting tricky!
Distilled water has a higher concentration of water than do human body cells. 
What type of solution is distilled water (hypertonic, hypotonic, isotonic)?
What would happen to your cells if you drank distilled water?

29. We’re getting tricky!
Distilled water has a lower concentration of minerals than do human body cells. 
What type of solution is distilled water (hypertonic, hypotonic, isotonic)?
What would happen to your cells if you took a bath in distilled water?

30. Everyone loves… WORKSHEETS!!!

31. Identify the type of solution
Describe what will move, and where
Explain how the cell’s volume will change
Exit Question
A cell contains a solution that is 44% water, and it is sitting in a solution that is 70% water.
A cell contains a solution that is 9% sugar, and it is sitting in a solution that is 88% sugar.