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Osmosis
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Osmosis is the movement of ___________ across a membrane from a region of high concentration to a
region of low concentration
Refers to the movement of water only.
There are three types of water solutions:
Type of Solution
Animal Cell
Plant Cell
Isotonic
The amount of water is the ______
on the inside and the outside of the
cell. Water will still flow back and
forth across the membrane, but at
the ______________ in both
directions.
Hypertonic
If a cell is placed in a hypertonic
solution, there is _______ water on
the ________ of the cell than on
the ___________ of the cell.
There is a net movement of water
_____ of the cell.
Plasmolysis:
Hypotonic
If a cell is placed in a hypotonic
solution, there is _______ water on
the _________ of the cell than on
the inside of the cell. There is a net
movement of water ______ the
cell.
Cytolysis:
In cells with a cell wall:
The central vacuole of a plant cell
will become extremely full of
water. _______________ will
increase. This helps to give
structure and support to a plant cell.
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Let’s Practice!!
Example #1: Label the drawing as we work through this.
1. The bag contains a 20% salt solution.
2. The water surrounding the bag is pure (100%) water.
3. What is the concentration of water inside the bag?
4. Is the bag hypotonic or hypertonic to the water on the outside?
5. Is the water on the outside hypertonic or hypotonic to the bag?
6. In which direction will water move?
7. In which direction will salt move?
8. What process might occur if too much water moves into the bag?
9. The movement of the salt and the water will continue until???
10. After equilibrium has been reached, what will happen to the movement of these molecules?
11. Water always moves from an area of _______ concentration to an area of _______ concentration. In other
words, water moves from the _______________ side to the _______________ side.
Example #2: Label the drawing as we work through this.
1. The bag contains a 40% sugar solution.
2. The water solution surrounding the bag contains a 40% sugar solution.
3. What is the concentration of water inside the bag?
4. What is the concentration of water on the outside of the bag?
5. What type of solutions are these?
6. In which direction will water move?
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Example #3: Label the drawing as we work through this.
1. The bag contains a 5% salt solution.
2. The water surrounding the bag contains a 25% salt solution.
3. What is the concentration of water inside the bag?
4. What is the concentration of water outside the bag?
5. Is the bag hypotonic or hypertonic to the water on the outside?
6. Is the water on the outside hypertonic or hypotonic to the bag?
7. In which direction will water move?
8. In which direction will salt move?
9. What process might occur if too much water leaves the bag?
10. The movement of the salt and the water will continue until???
11. After equilibrium has been reached, what will happen to the movement of these molecules?
12. Water always moves from an area of _________ concentration to an area of ______ concentration. In other
words, water moves from the _____________ side to the ______________ side.
Application
The red blood cells in your blood must constantly be in an isotonic condition. A 0.9% salt solution is
isotonic to red blood cells.
1. Draw a simple sketch of a red blood cell in isotonic solution. Label the inside and the outside of the
cell with the correct concentrations of salt and water.
2. Explain what will happen to the red blood cell if it is placed in a solution that is 99.3% water and 0.7%
salt. Is the cell hypertonic or hypotonic to the solution?
3. Explain what will happen to the red blood cell if it is placed in a solution that is 90% water and 10%
salt. Is the cell hypotonic or hypertonic to the solution?
4. What happens to an animal cell that is placed in a hypotonic solution? What is this condition called?
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5. What happens to a plant cell when placed in a hypotonic solution? What is this condition called?
6. Account for these differences in plant cells and animal cells in questions 12 and 13.
7. Describe what would happen to a cell that was placed in a hypertonic solution. Would it matter if the
cell were a plant cell or animal cell?
8. What would happen to the cell if it were placed in Beaker A?
Beaker B? Beaker C? Beaker D?
9. Which solution is isotonic to the cell?
10. Which solution(s) are hypertonic to the cell?
11. Which solution(s) are hypotonic to the cell?
12. Explain how osmosis…
a. A type of passive transport.
b. Similar to diffusion.
c. Different from facilitated diffusion.
d. Different from active transport.
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