5E Inquiry Lesson Plan
Title: OSMOSIS and DIFFUSION
Grade level: 7th and 8th
National Standards:
Evolution and Equilibrium; Change Constancy and Measurement; Evidence Models and
Explanations
ACOS:
Standards 1, 2, 3, 5,
Objectives:
1. The student will understand the processes and the effects of life activities in plants
and animals through osmosis and diffusion.
2. The student will understand how a solute size and concentration gradient affects
diffusion across semi-permeable membranes.
3. The student will understand the process of diffusion and its importance to cell
function.
4. The student will understand that osmosis is a specialized form of diffusion.
5. The student will view a Power Point Presentation and participate in an interactive
class discussion to learn basic facts about osmosis and diffusion.
6. The students will perform experiments involving osmosis and diffusion and record
data from these experiments using data tables and data analysis.
Procedures
Materials:
Teacher Demonstration:
Plastic cups, Gummy Bears, red Kool-Aid, 30% salt solution (150 grams of salt to 500ml
of water), celery stalks, hot and cold water. See Teacher Pre-Lab Guide
1
Part A:
Gloves, plastic bags, plastic cups, corn starch, water, Lugol’s solution (iodine),
graduated cylinder. See Teacher Pre-Lab Guide
Part B:
Gloves, plastic cups, dialysis tubing, graduated cylinder, scales, dental floss, distilled
water, tap water, 20% sucrose solution, phenolphthalein, ammonia, vinegar, universal
indicator solution, red food coloring, 40% sucrose solution. See Teacher Pre-Lab
Guide
Engage:
1st Day
Time: 50 minutes
Pre-Test – 20 minutes
3D Presentation
Demonstrations: Osmosis/Gummy Bears; Celery. Rate of diffusion/ Kool-Aid in hot and
cold water - 25 minutes. See Teacher Pre-Lab Guide
Explore:
2nd Day
Time: 50 minutes
Student Lab on Diffusion, Procedure steps 1 – 4 found in the Student Lab Guide
3rd Day
Time: 50 minutes
Finish the Diffusion Lab Handouts
Student Lab on Osmosis, Procedure steps 1 – 10 found in the Student Lab Guide
2
Explain:
4th Day
Time: 50 minutes
Osmosis Lab Procedure Steps 11 – 13
Discussion of lab results/Hand-Outs Part A & Part B
Power Point Presentation
Elaborate:
5th Day
Time: 20 Minutes
Problem Solving based on Osmosis/Diffusion, Handout 3
Evaluate:
5th Day
Time: 20 minutes
Post Test
Final Discussion Wrap Up
Safety:
Students will use gloves and handle chemicals with caution. Wash all spills and
splashes with water.
Prepared by: Dr. Debbie Payne, Ruth H. Liddell, Shirley K. Scarbrough
Alabama State University: Math, Science Partnership, Fall 2012
3
TEACHER PRE-LAB GUIDE
FOR DEMONSTRATION:
Materials:
Plastic cups
Gummy Bears
Package of Red Kool-Aid
30% Salt Solution
Celery Stalks
Hot/Cold Water
PREPARATION:
Soak Gummy Bears (one color per cup) overnight in water
Add 150 grams of salt to 500ml of HOT water; mix to dissolve as much as possible
Soak celery stalks in salt water overnight
Soak another celery stalk in tap water overnight
PROCEDURE:
1. As students enter the class, have them look at the demonstrations in the front of the
room.
a. Show students dry Gummy Bears and a cup of water. Ask students to write their
prediction of what will happen if the Gummy Bears are soaked overnight in the water.
b. Show students a cup of salt water and a stalk of celery. Ask students to write their
prediction of what will happen if the celery soaks overnight in salt water.
c. Show students a package of Kool Aid and a cup of hot water and a cup of cold water.
Ask students to write their prediction of what will happen to the Kool Aid when added to
the cup of hot water; cup of cold water.
2. Teacher will now show :
a. Gummy Bears soaked in water
b. Celery in salt water; celery in tap water
c. the effect of adding one teaspoon of Kool Aid into hot water; one teaspoon of Kool
Aid into cold water.
3. Teacher will lead a class discussion of student predictions and explanations of what
they learned.
For Part A: Diffusion:
Materials:
Each group needs:
Gloves —1 pair for each student
1 Plastic bag with 1 teaspoon of corn starch
1 Plastic cup
1 bottle of Lugol’s Solution (iodine)
1 graduated cylinder
Water (150 ml/per group)
Preparation:
1. Measure 1 teaspoon of corn starch and add to a plastic bag; close bag and label bag
Group1, 2, etc.
2. Put a plastic cup, a graduated cylinder, bottle of Lugol’s solution and the plastic bag
with corn starch at each lab group’s station.
3. Provide a large container of tap water at a central location in the classroom
4. Have a place assigned for each group to leave their plastic bag overnight
Procedure:
1. Pass out Part A Introduction and Instructions
2. Ask students to read all of the introduction and lab instructions prior to beginning the
lab
3. Pass out Handout 1, Part A
4. On second day, pass out Handout 2, Part A
For Part B: Osmosis
Materials:
ALL groups need:
1 plastic cup
one 8 inch pre-cut and soaked dialysis tubing
1 graduated cylinder
four 8 inch pre-cut pieces of dental floss
Scales
Gloves – 1 pair per student
Water
Additional Materials Needed:
Groups 1 and 2 need:
20% sucrose solution
Bottle of red food coloring
Groups 3 and 4 need:
Bottle of Phenolphthalein
Household Ammonia
Groups 5 and 6 need:
Bottle of vinegar
Bottle of Universal Indicator Solution
Groups 7 and 8 need:
Distilled water
40 % sucrose solution
Bottle of red food coloring
Preparation:
1. Cut dialysis tubing into 8 inch sections. Each group will need 1 piece.
2. One or two days before the lab, soak the dialysis tubing in distilled water, tubing
should be covered with water.
3. Cut four 8 inch pieces of dental floss for each group: for 8 groups, 32 pieces are
needed.
4. To prepare 20% sucrose solution:
Place 20 grams of sugar in 100ml of distilled water.
To prepare 40% sucrose solution place 40 grams of sugar place in 100ml of distilled
water (if this does not dissolve readily, heat the water to hasten the process).
5. Prior to beginning lab, place the following at each lab station:
1 piece of dialysis tubing in distilled water; 1 plastic cup; 1 graduated cylinder; Four 8
inch pieces of dental floss; 1 pair of gloves for each student
6. At a central location, place scales and tap water.
7. At another central location, have the additional materials needed for each group.
8. Have each group label their plastic cup with their group number.
9. Have a designated place for each group to leave their dialysis tubing in plastic cup
overnight.
Procedure:
1. Pass out Part B Introduction and Instruction
2. Make sure each group member reads all the background information and
instructions before starting.
3. Pass out Handout 1, Part B
4. When Handout 1, Part B is completed and turned in, pass out Handout 2, Part B.
EXPECTED RESULTS:
Part A: the solution inside the bag will eventually become blue – black; the solution
outside the bag will become colorless.
Part B: for Groups 1 &2 the mass of the dialysis tubing will increase and the solution
inside will become pinkish – red; for Groups 3 & 4 the mass of the dialysis tubing will
increase and the solution inside will become pinkish - purple; for Groups 5 & 6 the mass
of the dialysis tubing will increase and the solution will become pinkish – orange; for
Groups 7 & 8 the mass of the dialysis tubing will decrease and the solution in the cup
will become light pink.
ANSWERS HANDOUT 1 PART A:
DATA ANALYSIS QUESTIONS
1. Based on your observations, which substance moved, the Lugol’s solution (iodine) or
the starch? Lugol’s Solution or Iodine
2. How did you determine this? Lugol’s Solution/Iodine is an indicator which turns
starch blue/black over a period of time. The solution in the plastic bag, which
contains the starch, changed to this color and the solution in the plastic cup
became lighter.
3. The plastic bag was permeable (lets particles through) to which substance? It was
permeable to the Lugol’s Solution/Iodine
4. Is the plastic bag selectively permeable (lets some particles through but not all)?
Yes, it did not allow the corn starch to move.
5. Sketch the plastic cup and bag in the space below. Use arrows to indicate the
direction of diffusion in this lab. Answers will vary.
ANSWERS TO HANDOUT 2, PART A
DIFFUSION LAB CONCLUSION/PREDICTION QUESTIONS
1. In your own words define diffusion and give an example. Answers will vary.
2. What happened to the color in the bag that was left overnight? What happened to
the color in the plastic cup that was left overnight? It became darker until it spread
throughout the bag. The color in the plastic cup became lighter.
3. If the water containing Lugol’s solution (iodine) was heated, predict how this would
affect the time of a color change? The rate of the color change in the bag and the
plastic cup would increase.
4. Why is Lugol’s solution (iodine) called an indicator? The Lugol’s solution (iodine)
changes color from brown to black in the presence of the starch.
5. Molecules tend to move from an area of greater (higher) concentration to areas of
lesser (lower) concentration.
6. Is the bag or the plastic cup more concentrated in starch? Bag
7. Is the bag or plastic cup more concentrated in iodine? Plastic Cup
DIFFUSION LAB ELABORATE QUESTIONS
1. Predict which way the starch would move, into the bag or out of the bag, if the bag
was permeable to starch. It would move out of the bag Explain your answer.
Answers will vary.
2. Predict the way Lugol’s solution (iodine) would move, into or out of the bag, since the
bag is permeable to Lugol’s solution (iodine). It would move into the bag.
3. Since the bag is permeable to Lugol’s solution (iodine), what color would you expect
the solution in the bag to turn? Blue/black. Explain your answer. Answers will vary.
What about the solution in the plastic cup? The solution in the plastic cup will get
lighter. Explain your answer. Answers will vary.
4. If the bag was permeable to starch, what color would you expect the solution in the
bag to turn? It would become a lighter blue. Explain your answer. Answers will
vary.
What about the solution in the plastic cup? It would begin to turn blue. Explain your
answer. Answers will vary.
5. Predict what you think would happen if you did an experiment in which the Lugol’s
solution (iodine) was placed in the bag and the starch was in the plastic cup? Answers
will vary. BE DETAILED IN WRITING YOUR PREDICTION
ANSWERS TO HANDOUT 1, PART B
1. Sketch the tubes in the plastic cups and use arrows to show the movement of the
particles for each group. Answers will vary.
Sketch the tubes in the plastic cups and use arrows to show the movement of the water
molecules for each group. Answers will vary.
2. Which of these solutions are hypertonic for each group? Groups 7 & 8. Which of
these solutions are hypotonic for each group? Groups 1, 2, 3, 4, 5 & 6.
3. How do you know which way the particles move? The indicator changed colors in
Groups 3, 4, 5, 6. How do you know which way the water molecules moved? Change
in mass; in Groups 1, 2, 7, 8 by the movement of the red food coloring.
4. How is this similar to particle movement in cells? Answers will vary. How is this
similar to water movement in cells? Answers will vary.
Prepared by: Dr. Debbie Payne, Ruth H. Liddell, Shirley K. Scarbrough
Alabama State University, Math, Science Partnership, Fall 2012
Pre/Post Test – Osmosis, Diffusion
1. The diffusion of water molecules through a selectively permeable membrane is:
A. homeostasis B. osmosis C. active transport D. equilibrium
2. All matter is composed of very small particles called:
A. molecules B. ions C. solutes D. isotopes
3. The movement of molecules from a place where there is a greater/higher concentration to an area
where there is lesser/lower concentration is:
A. homeostasis B. diffusion C. osmosis D. active transport
4. A “steady state” or equilibrium that cells maintain internally is:
A. homeostasis B. osmosis C. diffusion
D. active transport
5. A selectively permeable membrane:
A. allows all substances to enter and leave B. prevents all substances from entering or leaving
C. allows certain size substances to enter and leave D. allows only waste materials to leave
6. Hypotonic solution:
A. has a higher concentration of water and a lower concentration of solutes than another solution
B. has a higher concentration of solutes and a lower concentration of water than other solutions
C. has an equal concentration of water and solutes as another solution
D. has more solutes than solvent than another solution
7. The openings in selectively permeable membranes are called:
A. homeostatic openings B. perforation C. diffusion holes D. pores
8. A solution in which the concentration of solutes is the same inside and outside of a cell is a
_______________________ solution:
A. hypertonic B. hypotonic C. isotonic D. homeotonic
9. If a red blood cell is placed in a solution that has a concentration gradient higher than the red blood
cell, this type of solution is called:
A. isotonic B. hypotonic C. hypertonic D. homeotonic
10. If a red blood cell is placed in a hypotonic solution, it will eventually:
A. shrink up B. swell and burst C. no change will occur D. swell and not burst
11. When substances move in and out of cells using only their own kinetic energy this is called:
A. active transport B. passive transport C. activation energy D. selective transport
12. When placed in a hypotonic solution, plant cells:
A. will swell and burst B. will shrink and burst C. will cause the plant to wilt D. will increase in
turgor pressure
13. Osmosis is sometimes referred to as:
A. turgor pressure B. homeostasis C. active transport D. specialized diffusion
14. An example of diffusion is:
A. water molecules moving into a plant cell after rain
B. red food coloring moving through water until the water is pink
C. water molecules leaving the cells of a fresh water fish, when placed in a salt water tank
D. none of the above
15. Dialysis tubing has a similar function as:
A. a cell membrane B. a selectively permeable membrane C. Both A & B D. neither A nor B
16. An example of an indicator is:
A. Lugol’s solution B. phenolphthalein C. universal indicator solution D. all of the above
17. Which way will water molecules move if a red blood cell is placed in distilled water?
A. out of the red blood cell B. into the red blood cell
C. water molecules will move in and out at the same rate D. no water molecules will move
18. Because the human body is 60% water, an important process which helps humans and all living
things maintain a “normal” internal cellular environment even when external surroundings are constantly
changing is:
A. diffusion B. osmosis C. active transport D. carrier transport
19. Molecular movement continues even when there is no overall change in concentration. This is
referred to as:
A. active transport B. passive transport C. homeostasis D. dynamic equilibrium
20. The difference in the concentration of a substance across a space is called:
A. kinetic energy gradient B. solvent gradient C. concentration gradient D. dynamic equilibrium
Pre/Post Test – Osmosis, Diffusion
1. The diffusion of water molecules through a selectively permeable membrane is:
A. homeostasis B. osmosis C. active transport D. equilibrium
2. All matter is composed of very small particles called:
A. molecules B. ions C. solutes D. isotopes
3. The movement of molecules from a place where there is a greater/higher concentration to an area
where there is lesser/lower concentration is:
A. homeostasis B. diffusion C. osmosis D. active transport
4. A “steady state” or equilibrium that cells maintain internally is:
A. homeostasis B. osmosis C. diffusion
D. active transport
5. A selectively permeable membrane:
A. allows all substances to enter and leave B. prevents all substances from entering or leaving
C. allows certain size substances to enter and leave D. allows only waste materials to leave
6. Hypotonic solution:
A. has a higher concentration of water and a lower concentration of solutes than another
solution
B. has a higher concentration of solutes and a lower concentration of water than other solutions
C. has an equal concentration of water and solutes as another solution
D. has more solutes than solvent than another solution
7. The openings in selectively permeable membranes are called:
A. homeostatic openings B. perforation C. diffusion holes D. pores
8. A solution in which the concentration of solutes is the same inside and outside of a cell is a
_______________________ solution:
A. hypertonic B. hypotonic C. isotonic D. homeotonic
9. If a red blood cell is placed in a solution that has a concentration gradient higher than the red blood
cell, this type of solution is called:
A. isotonic B. hypotonic C. hypertonic D. homeotonic
10. If a red blood cell is placed in a hypotonic solution, it will eventually:
A. shrink up B. swell and burst C. no change will occur D. swell and not burst
11. When substances move in and out of cells using only their own kinetic energy this is called:
A. active transport B. passive transport C. activation energy D. selective transport
12. When placed in a hypotonic solution, plant cells:
A. will swell and burst B. will shrink and burst C. will cause the plant to wilt D. will increase in
turgor pressure
13. Osmosis is sometimes referred to as:
A. turgor pressure B. homeostasis C. active transport D. specialized diffusion
14. An example of diffusion is:
A. water molecules moving into a plant cell after rain
B. red food coloring moving through water until the water is pink
C. water molecules leaving the cells of a fresh water fish, when placed in a salt water tank
D. none of the above
15. Dialysis tubing has a similar function as:
A. a cell membrane B. a selectively permeable membrane C. Both A & B D. neither A nor B
16. An example of an indicator is:
A. Lugol’s solution B. phenolphthalein C. universal indicator solution D. all of the above
17. Which way will water molecules move if a red blood cell is placed in distilled water?
A. out of the red blood cell B. into the red blood cell
C. water molecules will move in and out at the same rate D. no water molecules will move
18. Because the human body is 60% water, an important process which helps humans and all living
things maintain a “normal” internal cellular environment even when external surroundings are constantly
changing is:
A. diffusion B. osmosis C. active transport D. carrier transport
19. Molecular movement continues even when there is no overall change in concentration. This is
referred to as:
A. active transport B. passive transport C. homeostasis D. dynamic equilibrium
20. The difference in the concentration of a substance across a space is called:
A. kinetic energy gradient B. solvent gradient C. concentration gradient D. dynamic equilibrium
OSMOSIS and DIFFUSION
Molecules are always moving
Molecules move randomly and bump into
each other and other barriers
Concentration gradient
Concentration Gradient - change in the concentration of a
substance from one area to another.
Diffusion
Molecules in solution tend to slowly spread
apart over time. This is diffusion.
T1
T2
T3
Diffusion
•
•
Movement of molecules from an area of high
concentration to an area of lower concentration.
Factors that affect the rate of diffusion: size of
molecules, size of pores in membrane,
temperature, pressure, and concentration.
Diffusion
concentrated, high energy molecules
[High]
[Low]
diffuse, low energy molecules
Diffusion will continue until equilibrium is reached.
This means there will be an equal distribution of
molecules throughout the space. This is why food
coloring moves throughout a beaker of water; why odors
smell strong at first and then disappear over time.
Equilibrium, a result of diffusion, shows the uniform distribution of
molecules of different substances over time as indicated in the
above diagram.
Which molecules will diffuse in each of the figures below?
1
2
5
3
6
4
ANSWERS
1
2
3
4
No Movement
5
6
No Movement
Osmosis
• Osmosis is the movement of WATER across a semi‐permeable membrane
• At first the concentration of solute is very high on the left.
• But over time, the water moves across the semi‐
permeable membrane and dilutes the particles. Osmosis – A Special kind of Diffusion
Diffusion of water across a selectively permeable membrane (a
barrier that allows some substances to pass but not others).
The cell membrane is such a barrier.
Small molecules pass through – ex: water
Large molecules can’t pass through – ex: proteins and
complex carbohydrates
Hypotonic – The solution on one side of a membrane where the solute
concentration is less than on the other side. Hypotonic Solutions contain a low
concentration of solute relative to another solution.
Hypertonic – The solution on one side of a membrane where the solute
concentration is greater than on the other side. Hypertonic Solutions contain a
high concentration of solute relative to another solution.
Over time molecules will move across the
membrane until the concentration of
solutes is equal on both sides. This type of
solution is called ISOTONIC.
• Cytoplasm is a solution of water and solids
(solutes dissolved in the water).
• Water moves into and out of cells because of the
different concentrations of the solutes.
• Different kinds of cells react differently depending on
the solution they are in.
• Below are examples of red blood cells in different
types of solutions and shows what happened to the
red blood cells.
PLANT CELLS
Hypotonic
Solution
Turgor Pressure builds in the
cell and causes osmosis to stop
because of the rigid cell wall.
Hypertonic
Solution
Plants will wilt when cells
lose water through osmosis.
ELODEA CELLS
As viewed under the microscope
PASSIVE TRANSPORT
Passive transport occurs without expenditure of energy.
Molecules move using their own kinetic energy . Diffusion and
osmosis are examples of passive transport. Passive transport
allows cells to get water, oxygen and other small molecules that
they need. It also allows the cell to get rid of waste such as
carbon dioxide.
DIFFUSION
OSMOSIS
THE END
STUDENT LAB GUIDE
DIFFUSION: INTRODUCTION and INSTRUCTIONS
Part A: Diffusion
All matter is composed of very small particles called molecules. Molecules are always
moving. Although we cannot see them moving with our naked eye or even with a
microscope, we can observe evidence of this movement in other ways.
Molecules of the same substance, using their own energy, will move from a space
where they are close together (higher concentration) into a space where they are farther
apart (lower concentration). This movement, called diffusion, will continue until
molecules become evenly distributed and there is no concentration gradient (the
difference in concentration of a substance across a space). When molecules are evenly
distributed, equilibrium is reached and diffusion will stop. Molecular movement
continues but there is no overall change in concentration. This is called dynamic
equilibrium. A system is most stable when it has reached equilibrium.
In scientific terminology diffusion is defined as “the movement from an area of higher
(greater) concentration to an area of lower (lesser) concentration.
The rate of diffusion (how fast diffusion takes place) can be affected by the following
factors: concentration, temperature, pressure, molecular size.
1. READ the INTRODUCTION
2. Materials:
Gloves
Plastic bags containing corn starch (1 teaspoon)
Plastic cups
Lugol’s solution (iodine)*
Graduated cylinder
Water
1 *Lugol’s solution is an example of an indicator. An indicator is a substance that
changes color in the presence of the substance it indicates.
PROCEDURE:
1. Add 150ml of water to the plastic bag containing corn starch. Remove as much air
as possible and seal the bag. Mix by moving contents of bag back and forth gently to
dissolve corn starch.
2. Groups 1 and 2 add 10 drops of Lugol’s solution and 250ml of water to a plastic cup;
Groups 3 and 4 add 20 drops of Lugol’s solution and 250ml of water to a plastic cup;
Groups 5 and 6 add 30 drops of Lugol’s solution and 250ml of water to a plastic cup;
Groups 7 and 8 add 40 drops of Lugol’s solution and 250ml of water to a plastic cup.
3. BE SURE YOUR PLASTIC BAG IS COMPLETELY SEALED. Record the starting
colors on Handout 1, Table A. Then place the SEALED bag containing the corn starch
solution into the plastic cup containing Lugol’s solution so that the contents of the bag
are completely covered by the solution.
4. After 10 minutes, observe any changes in color and record your data in Handout 1,
Table A; after 30 minutes observe any changes in color and record your data in
Handout 1, Table A. Leave your bag in the plastic cup overnight. Make your final
observation of colors the next day and record your data in Handout 1, Table A.
5. Answer Data Analysis Questions 1 – 5 on Handout 1, Part A.
6. Answer Conclusion Questions 1 – 7 on Handout 2, Part A.
7. Answer Elaborate Questions 1 – 5 on Handout 2, Part A.
Prepared by: Dr. Debbie Payne, Ruth H. Liddell, Shirley K. Scarbrough
Alabama State University, Math, Science Partnership, Fall, 2012
2 STUDENT LAB GUIDE
OSMOSIS: INTRODUCTION and INSTRUCTIONS
Part B: Osmosis
Another process that is closely related to diffusion and is sometimes referred to as
“Specialized Diffusion” is osmosis. Osmosis is the diffusion of water molecules through
a selectively permeable membrane (one which only allows certain materials to pass
through).
In the process of osmosis, water molecules pass through a selectively permeable
membrane from an area where there are many water molecules into an area where
there are fewer water molecules.
The cells in plants and animals are surrounded by membranes that are selectively
permeable. In addition, a plant cell’s membrane is further enclosed by a fairly rigid
structure called a cell wall; animal cells do not have a cell wall surrounding their cell
membranes.
The selectively permeable cell membrane of plant and animal cells contains pores
(small openings) that can control what enters and leaves the cells.
Plant and animal cells are exposed to many changes in their external environment.
They must keep a stable internal environment in order to carry out the normal cellular
activities necessary for life functions. The cells of plants and animals must maintain a
balance or “steady state” within each cell to stay alive. This internal balance is called
homeostasis. All cells are surrounded by water solutions. A solution in which the
concentration of dissolved substances (solutes) is the same inside and outside the cell
is called an isotonic solution (iso means the same). A solution in which the
concentration of dissolved substances (solutes) is higher outside the cell than inside the
cell is called a hypertonic solution (hyper means greater). A solution in which the
concentration of dissolved substances (solutes) is lower outside the cell than inside the
cell is called a hypotonic solution (hypo means less).
Because the membranes of both plant and animal cells can tell different substances
apart, they can act as “gate-keepers” for the cells. They can slow down or even stop
certain materials from entering or leaving the cell. They can also allow certain
substances to pass through freely. When substances move in and out of cells without
1 having to use any energy other than their own kinetic energy, the process is called
passive transport. Osmosis and diffusion are both examples of passive transport.
Passive transport allows cells to get water, oxygen and other small molecules that they
need. It also allows the cell to get rid of wastes such as carbon dioxide.
Because the human body is made up of 60% water, osmosis is an important process.
This process helps humans and all organisms to maintain their “normal” internal
environment even when their surroundings are constantly changing.
1. READ the INTRODUCTION
2. Materials:
All Groups
Groups 1 & 2
Groups 3 & 4
Groups 5 & 6 Groups 7 & 8
1. Plastic cups
2. Dialysis Tubing
(One 8 inch piece)
3. Graduated Cylinder
4. Dental Floss (Four 8
inch pieces)
5. Scales
6. Gloves
7. Water
1. 20% Sucrose
Solution
2. Red Food
Coloring
1.Phenolphthalein
2. Ammonia
1. Vinegar
2. Universal
Indicator
Solution
1. Distilled
Water
2. 40%
Sucrose
Solution
3. Red Food
Coloring
PROCEDURE:
1. All groups: Moisten your fingers to open the dialysis tubing. Tie a knot at one end of
the tubing approximately 1 inch from the end (knot 1) using dental floss; approximately
1 inch above the knot tie another knot (knot 2) using dental floss. TIE ALL KNOTS
TIGHTLY. MAKE SURE YOU HAVE SECURE KNOTS (NO LEAKAGE).
Keep the dialysis tube moist but avoid getting water inside the tube.
2 Knot 2 Knot 1
2. Groups 1 & 2: Fill the dialysis tube 1/3 full with 20% Sucrose solution.
Groups 3 & 4: Fill the dialysis tube 1/3 full with phenolphthalein (~40 drops)
Groups 5 & 6: Fill the dialysis tube 1/3 full with Universal Indicator (~40 drops)
Groups 7 & 8: Fill the dialysis tube 1/3 full with distilled water (~40 drops). Add
one drop of red food coloring to the dialysis tube.
3. ALL Groups: Approximately 1 inch from the open end of the tubing tie one knot
using dental floss and using the same CAREFUL technique used in Step 1 (Knot 1).
Approximately 1 inch below Knot 1 tie the tubing again (Knot 2).
Dental Floss
Knot 1
Knot 2 Open space
Tubing Fill Original knots 4. All Groups: Carefully rinse off the outside of the tube to remove anything that may
have spilled on it. Gently pat it dry with a paper towel.
3 STEP NUMBER 5 MUST BE COMPLETED BEFORE YOU PROCEED
ANY FURTHER!!!
5. All Groups: Using the scales, find the mass of the filled dialysis tube. Record this
information on Handout 1 – Part B on Data Table A.
6. Groups 1 & 2: Put 100ml of water in a plastic cup. Add one drop of red food
coloring to the water.
7. Groups 3 & 4: Put 75ml of water in a plastic cup. Add 25ml of ammonia to the
water.
8. Groups 5 & 6: Put 75ml of water in a plastic cup. Add 25ml of vinegar to the water.
9. Groups 7 & 8: Put 100ml of 40% sucrose solution in a plastic cup.
10. ALL Groups: Place your dialysis tube in the plastic cup with the solution you made.
Make sure it is fully covered. Observe and record the beginning color and your results
after 15 minutes or until color change on Handout 1 – Part B, Data Table B.
Leave the dialysis tubing in the plastic cup overnight.
THE NEXT DAY:
11. Observe and record the overnight results in Handout 1, Part B, Data Table B.
12. ALL Groups: Remove the dialysis tube, gently pat it dry and find the mass using
the scales. Record this data Handout 1 – Part B, Table A.
13. ALL Groups: Compare your data with the other groups that tested different
substances. Record the results from the other groups in the correct Tables A and B.
Prepared by: Dr. Debbie Payne, Ruth H. Liddell, Shirley K. Scarbrough
Alabama State University, Math, Science Partnership, Fall 2012
4 HANDOUT 1 – PART A
TABLE A
Groups
Solutions
Groups 1 - 2
Solution in
Plastic Cup
Solution in
Bag
Solution in
Plastic Cup
Solution in
Bag
Solution in
Plastic Cup
Solution in
Bag
Solution in
Plastic Cup
Solution in
Bag
Groups 1 - 2
Groups 3 - 4
Groups 3 - 4
Groups 5 - 6
Groups 5 - 6
Groups 7 -8
Groups 7 -8
Starting
Color
Color after
10 minutes
Color after
30 minutes
Color
Overnight
DATA ANALYSIS QUESTIONS
1. Based on your observations, which substance moved, the Lugol’s solution (iodine) or
the starch?
2. How did you determine this?
3. The plastic bag was permeable (lets particles through) to which substance?
1 4. Is the plastic bag selectively permeable (lets some particles through but not all)?
5. Sketch the plastic cup and bag in the space below. Use arrows to indicate the
direction of diffusion in this lab.
Prepared by: Dr. Debbie Payne, Ruth H. Liddell, Shirley K. Scarbrough
Alabama State University, Math, Science Partnership, Fall 2012
2 HANDOUT 2 – PART A
DIFFUSION LAB CONCLUSION/PREDICTION QUESTIONS
1. In your own words define diffusion and give an example.
2. What happened to the color in the bag that was left overnight? What happened to
the color in the plastic cup that was left overnight?
3. If the water containing Lugol’s solution (iodine) was heated, predict how this would
affect the time of a color change?
4. Why is Lugol’s solution (iodine) called an indicator?
5. Molecules tend to move from an area of _____________________ concentration to
areas of ____________________ concentration.
6. Is the bag or the plastic cup more concentrated in starch?
7. Is the bag or plastic cup more concentrated in iodine?
DIFFUSION LAB ELABORATE QUESTIONS
1. Predict which way the starch would move, into the bag or out of the bag, if the bag
was permeable to starch. Explain your answer.
1 2. Predict the way Lugol’s solution (iodine) would move, into or out of the bag, since the
bag is permeable to Lugol’s solution (iodine).
3. Since the bag is permeable to Lugol’s solution (iodine), what color would you expect
the solution in the bag to turn? Explain your answer.
What about the solution in the plastic cup? Explain your answer.
4. If the bag was permeable to starch, what color would you expect the solution in the
bag to turn? Explain your answer.
What about the solution in the plastic cup? Explain your answer.
5. Predict what you think would happen if you did an experiment in which the Lugol’s
solution (iodine) was placed in the bag and the starch was in the plastic cup?
BE DETAILED IN WRITING YOUR PREDICTION
Prepared by: Dr. Debbie Payne, Ruth H. Liddell, Shirley K. Scarbrough
Alabama State University, Math, Science Partnership, Fall 2012
2 HANDOUT 1 – PART B
TABLE A
Group 1 & 2
Group 3 & 4
Group 5 & 6 Group 7 & 8
Original Mass of
the Tube (grams)
Final Mass of
Tube (grams)
TABLE B
Group 1
&2
Beginning
Color
After 15 minutes or until
color change
Overnight
Color
Group 3
&4
Group 5
&6
Group 7
&8
In Tubing
In Plastic
Cup
In Tubing
In Plastic
Cup
In Tubing
In Plastic
Cup
1 Answer the following questions based on the Osmosis Lab
1. Sketch the tubes in the plastic cups and use arrows to show the movement of the
particles for each group.
Sketch the tubes in the plastic cups and use arrows to show the movement of the water
molecules for each group.
2. Which of these solutions are hypertonic for each group? Which of these solutions
are hypotonic for each group?
2 3. How do you know which way the particles move? How do you know which way the
water molecules moved?
4. How is this similar to particle movement in cells? How is this similar to water
movement in cells?
Prepared by: Dr. Debbie Payne, Ruth H. Liddell, Shirley K. Scarbrough
Alabama State University, Math, Science Partnership, Fall 2012
3 HANDOUT 2 – PART B
Describe osmosis. Use evidence from all parts (ALL groups’ data) of this lab to back
up what you say. Discussions that do not include evidence will be considered not
answered.
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Prepared by: Dr. Debbie Payne, Ruth H. Liddell, Shirley K. Scarbrough
Alabama State University, Math, Science Partnership, Fall 2012
HANDOUT 3 (problem solving)
Based on the results from the labs on Diffusion and Osmosis, apply your knowledge to
answer the following:
The cells of fish that live in fresh water contain more solute than the water in the lake or
stream that surrounds the fish. A cell membrane is selectively permeable, like the
dialysis tubing from your lab.
Draw a picture representing the situation and apply problem solving steps. Will water
move into or out of the cells of the fish? Explain how you arrived at your answer. What
term do you use to express this process?
Prepared by: Dr. Debbie Payne, Ruth H. Liddell, Shirley K. Scarbrough
Alabama State University, Math, Science Partnership, Fall 2012
OSMOSIS and DIFFUSION LAB
2013
Please circle the letter that best describes your opinion of this Lab.
1. The lab’s goals and objectives were clear.
a. strongly agree b. agree c. somewhat agree d. disagree e. strongly disagree
2. The subject matter of the lab was interesting.
a. strongly agree b. agree c. somewhat agree d. disagree e. strongly disagree
3. The material covered was understandable.
a. strongly agree b. agree c. somewhat agree d. disagree e. strongly disagree
4. Overall I would rate the value of this lab…..
a. excellent b. good c. about average d. fair e. poor
OSMOSIS and DIFFUSION LAB
2013
Please circle the letter that best describes your opinion of this Lab.
1. The lab’s goals and objectives were clear.
a. strongly agree b. agree c. somewhat agree d. disagree e. strongly disagree
2. The subject matter of the lab was interesting.
a. strongly agree b. agree c. somewhat agree d. disagree e. strongly disagree
3. The material covered was understandable.
a. strongly agree b. agree c. somewhat agree d. disagree e. strongly disagree
4. Overall I would rate the value of this lab…..
a. excellent b. good c. about average d. fair e. poor