BIOL 1406

PreLab 5.3

How does solute concentration affect dialysis and osmosis?

In addition to simple diffusion and facilitated diffusion, two other types of diffusion play an extremely important role in transporting substances across cell membranes:

Use the interactive exercises below to learn more about dialysis and osmosis.



 

Your Turn
The following diagram represents a container with two aqueous solutions separated by a selectively permeable membrane. Water and both solutes can pass through the membrane freely.

Before equilibrium is reached in this container:
1. Movement of glucose across the membrane can best be described as
A. left to right B. right to left C. both directions D. neither direction		 Hint Check your answer.
2. Net movement of glucose across the membrane can best be described as
A. left to right B. right to left C. both directions D. neither direction		 Hint Check your answer.
3. Movement of fructose across the membrane can best be described as
A. left to right B. right to left C. both directions D. neither direction		 Hint Check your answer.
4. Net movement of fructose across the membrane can best be described as
A. left to right B. right to left C. both directions D. neither direction		 Hint Check your answer.
5. Movement of water across the membrane can best be described as
A. left to right B. right to left C. both directions D. neither direction		 Hint Check your answer.
6. Net movement of water across the membrane can best be described as
A. left to right B. right to left C. both directions D. neither direction		 Hint Check your answer.
7. Compared to the solution on the right, the solution on the left is best described as
A. isotonic B. hypotonic C. hypertonic		 Hint Check your answer.
8. Compared to the solution on the left, the solution on the right is best described as
A. isotonic B. hypotonic C. hypertonic		 Hint Check your answer.
9. Net movement of water is
A. from the hypertonic solution to the hypotonic solution
B. from the hypotonic solution to the hypertonic solution
C. both directions
D. neither direction		 Hint Check your answer.
After equilibrium is reached in this container:
1. Movement of glucose across the membrane can best be described as
A. left to right B. right to left C. both directions D. neither direction		 Hint Check your answer.
2. Net movement of glucose across the membrane can best be described as
A. left to right B. right to left C. both directions D. neither direction		 Hint Check your answer.
3. Movement of fructose across the membrane can best be described as
A. left to right B. right to left C. both directions D. neither direction		 Hint Check your answer.
4. Net movement of fructose across the membrane can best be described as
A. left to right B. right to left C. both directions D. neither direction		 Hint Check your answer.
5. Movement of water across the membrane can best be described as
A. left to right B. right to left C. both directions D. neither direction		 Hint Check your answer.
6. Net movement of water across the membrane can best be described as
A. left to right B. right to left C. both directions D. neither direction		 Hint Check your answer.
7. Compared to the solution on the right, the solution on the left is best described as
A. isotonic B. hypotonic C. hypertonic		 Hint Check your answer.
8. Compared to the solution on the left, the solution on the right is best described as
A. isotonic B. hypotonic C. hypertonic		 Hint Check your answer.

 

Your Turn
If a cell is placed in an isotonic solution:
1. Movement of water will be
A. into the cell B. out of the cell C. both in and out D. neither direction		 Hint Check your answer.
2. Net movement of water will be
A. into the cell B. out of the cell C. both in and out D. neither direction		 Hint Check your answer.
3. The cell will tend to
A. shrink B. swell C. both D. neither		 Hint Check your answer.
If a cell is placed in a hypotonic solution:
1. Movement of water will be
A. into the cell B. out of the cell C. both in and out D. neither direction		 Hint Check your answer.
2. Net movement of water will be
A. into the cell B. out of the cell C. both in and out D. neither direction		 Hint Check your answer.
3. The cell will tend to
A. shrink B. swell C. both D. neither		 Hint Check your answer.
If a cell is placed in a hypertonic solution:
1. Movement of water will be
A. into the cell B. out of the cell C. both in and out D. neither direction		 Hint Check your answer.
2. Net movement of water will be
A. into the cell B. out of the cell C. both in and out D. neither direction		 Hint Check your answer.
3. The cell will tend to
A. shrink B. swell C. both D. neither		 Hint Check your answer.



Osmosis across membranes made of dialysis tubing

In part III of the Lab Procedures, you will set up an experiment to study both dialysis and osmosis using bags made of dialysis tubing. Dialysis tubing is a type of semi-permeable membrane made from regenerated cellulose. The selectivity of the membrane is based on size. Holes in the membrane allow the passage of small molecules but not larger ones. In general, water and small solutes can pass freely through the dialysis tubing membrane while larger solutes cannot.

During this experiment, four bags will be filled with different solutions and then placed in beakers also filled with different solutions. Each bag will be weighed at the beginning and end of the experiment in order to determine whether net movement of water was into the bag, out of the bag, or neither. If a bag increases in weight that means net movement of water was into the bag; if a bag decreases in weight that means net movement of water was out of the bag; and if there is no change in weight that means there was no net movement of water.


 

Your Turn
Read Part III of the Lab Procedures and then answer the following questions based on the experimental set-up for beaker and bag # 1.
According to the Lab Procedures, what will be inside beaker #1? Hint Check your answer.
According to the Lab Procedures, what will be inside bag #1? Hint Check your answer.
During the experiment, what do you predict will happen to the weight of bag #1

A. It will increase
B. It will decrease
C. It will remain the same
 		 Hint Check your answer.
Explain your prediction: Hint Check your answer.


 

Your Turn
Read Part III of the Lab Procedures and then answer the following questions based on the experimental set-up for beaker and bag # 2.
According to the Lab Procedures, what will be inside beaker #2? Hint Check your answer.
According to the Lab Procedures, what will be inside bag #2? Hint Check your answer.
During the experiment, what do you predict will happen to the weight of bag #2

A. It will increase
B. It will decrease
C. It will remain the same 		Hint Check your answer.
Explain your prediction: Hint Check your answer.



 

Your Turn
Read Part III of the Lab Procedures and then answer the following questions based on the experimental set-up for beaker and bag # 3.
According to the Lab Procedures, what will be inside beaker #3? Hint Check your answer.
According to the Lab Procedures, what will be inside bag #3? Hint Check your answer.
During the experiment, what do you predict will happen to the weight of bag #3

A. It will increase
B. It will decrease
C. It will remain the same 		Hint Check your answer.
Explain your prediction: Hint Check your answer.

 

Your Turn
Read Part III of the Lab Procedures and then answer the following questions based on the experimental set-up for beaker and bag # 4.
According to the Lab Procedures, what will be inside beaker #4? Hint Check your answer.
According to the Lab Procedures, what will be inside bag #4? Hint Check your answer.
During the experiment, what do you predict will happen to the weight of bag #4

A. It will increase
B. It will decrease
C. It will remain the same 		Hint Check your answer.
Explain your prediction: Hint Check your answer.


 


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