1. Osmosis- diffusion of water across a
semipermeable membrane.

2. Water crosses membrane to reach equilibrium, since other molecule cannot.

3. Water crosses membrane to reach equilibrium, since other molecule cannot.

4. Sometimes the cell even shrinks or swells.
Where is there a greater concentration of the “yellow” molecules.

5. Put salt water on the outside.

6. Why?

7. Based on the distribution of these molecules, what
The diagram represents a cell in water. Formulas of molecules that can move freely across the cell membrane are shown. Some molecules are located inside the cell and others are in the water outside the cell.
Based on the distribution of these molecules, what
would most likely happen after a period of time?
The concentration of O2 will increase inside the cell.
(2) The concentration of CO2 will remain the same inside the
cell.
(3) The concentration of O2 will remain the same outside the
(4) The concentration of CO2 will decrease outside the cell.

8. What is it called if ATP energy is required to move things across a membrane?

9. Add
fresh
water
Add
salty
water

10. On inside On outside Equal Equal On outside On inside
cell On
inside On
outside
Out In
Out
&
Equal
Equal On
outside On
inside In

11. Animal cells have no cell wall.
If they are exposed to salty water they also shrink (dehydrate), but if exposed to distilled (100 % ) water they burst!

12. Why is the plant “sad”?

13. Why is the plant now “happy”?

15. The diagram represents a plant cell in tap water as seen with a compound light microscope.
Which diagram best represents the appearance of the cell after it has been placed in a 15% salt solution for two minutes?
(1) (2) (3) (4)