Lesson Code (Course - Master Objective # - Benchmark # - Lesson # - #)
 Biology B-3-1-1-1
Title - Author
 Cell Transport – Rhonda Cook
Benchmark/Expectation/Concept/Process/Skill
 3-1: Compare and contrast ways in which cells transport materials in and out of the cell.
Relevant Goals
Show-Me
Process
 1.6
Show-Me
Science Content
 3
Missouri
Science G(C)LE(s)
 3.2.A: c
 3.2.F: a-c
SJSD
6
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National
(5-8, 9-12)
 C
Learning Path
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Previous Learning
3.2.A: a. Describe how the
cell membrane helps
regulate the transfer of
materials in and out of the
cell
3.2.B: c. Describe the
importance of the transport
and exchange of oxygen
and carbon dioxide to the
survival of the organism
3.2.C: e. Identify the
importance of the transport
and exchange of nutrient
and waste molecules to the
survival of the cell and
organism
3.2.F: a. Predict the
response the body may
take to maintain internal
balance during an
environmental change
(e.g., shivering when cold,
slowing metabolism when
food supply decreases or
when dehydrated,
adrenaline rush when
frightened)
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Targeted Learning
3.2.A: c. Explain physical
and chemical interactions
that occur between
organelles (e.g. nucleus,
cell membrane,
chloroplast,
mitochondrion, ribosome)
as they carry out life
processes.
3.2.F: a. Explain the
significance of the
selectively permeable
membrane to the transport
of molecules
3.2.F: b. Predict the
movement of molecules
across a selectively
permeable membrane (i.e.,
diffusion, osmosis, active
transport) needed for a cell
to maintain homeostasis
given concentration
gradients and different
sizes of molecules
3.2.F: c. Explain how
water is important to cells
(e.g., is a buffer for body
temperature, provides
soluble environment for
chemical reactions, serves
as a reactant in chemical
reactions, provides
Future Learning
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hydration that maintains
cell turgidity, maintains
protein shape)
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Possible Misconceptions
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Teacher Notes
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Engage: Engages the learner’s mind in the concept, process, or skill to be learned, and makes
connections between prior experiences and the current learning goals.
Ask the following questions to generate discussion to get the students thinking.
 What is transportation?
 What is its purpose?
 What are some different types of transportation? (make sure that motor vehicles, nonmotored vehicles and body power are all considered)
 When considering cells and cell structure, why would it be important for molecules to be
able to move around?
Set up the activity “Spread the Smell”. This experiment is about diffusion. Explain that
diffusion happens in liquids as well but it takes a bit longer for diffusion to occur in liquids.
Materials you will need:
 Jar of coffee
 Bottle of vinegar
 Bottle of spray perfume
 An orange
 Room freshener (Aerosol spray)
 Basil Plant (herb)
(Choose at least two of the above)
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A fan (optional)
Some helpers/volunteers
Some blind folds (optional)
A stop clock (optional)
A note pad and pencil
Spread the Smell Steps:
1. Place your items of on a table at the front of the room. If you are going to use a fan place it at
the front of the room with you so that the air blows towards you participants.
2. Have your helpers form a line at the front of the room. Then ask each volunteer to (excluding
the first person in the line) take one step backwards to form a bit of a gap between each of them.
3. Ask your helpers to place their blind fold on or ask them to keep their eyes closed.
4. Leave the fan switched off. Ask your helpers to raise their hand if/when they smell something
different in the air.
5. Open the lid or spray one of your items and see how long it takes for the aroma to reach each
of your helpers. You could record your results by using a stop clock to see how long it takes for
each smell to reach each person. One test could be with the fan off and the other could be with
the fan switched on.
If you choose to use a basil plant in your experiment it is probably best if you hold the plant and
walk past each person in the line. As you get close to each person place one hand on the top
leaves of the plant and just fan them slightly with your hand to help the aroma to move through
the air. It is amazing how powerful a basil plant can smell.
This experiment is about diffusion. What is diffusion? Diffusion happens when particles mix
with each other without anything moving them. Smells move around a room and some end up in
our nose where we have smell detectors (our sense of smell). Gas particles move on their own in
the air and therefore the smells mix and spread. With the use of a fan the smells move through
the air faster.
Diffusion happens in liquids as well but it takes a bit longer for diffusion to occur in liquids.
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Formative Assessment(s):
Explore: Provides or creates a common experience for all learners and helps the teacher
identify the prior knowledge of each learning to build on. This stage allows time for the learner
to explore their ideas. This stage should be concrete and meaningful to the learner.
Discuss the following terms and definitions with the class.
 Passive Transport
Movement of molecules from a more crowded to a less crowded area WITHOUT
the use of energy. Movement occurs when there are unequal concentrations of a
substance inside and outside the cell.
 Diffusion
Diffusion is the movement of molecules from an area of higher concentration to a
region of lower concentration.
 Osmosis
Diffusion of water through a membrane
 Active Transport
Movement of molecules from a more crowded to a less crowded area WITH the
use of energy. Molecules are “carried” into or out of the cell using some the cell’s
energy.
 Homeostasis
The ability or tendency of an organism or cell to maintain internal equilibrium by
adjusting its physiological processes.
 Selective Permeability
Selective permeability means that the cell membrane has some control over what
can cross it, so that only certain molecules either enter or leave the cell. (Like a
screen on a window that will let air pass through, but not many insects.)
Notes on Diffusion and Osmosis. These can be printed and used as handouts. There are also a
couple of animated examples of diffusion and osmosis.
http://www.biologycorner.com/bio1/diffusion.html#
Notes on Active Transport. Can also be used as a handout.
http://www.biologycorner.com/bio1/active.html
Osmosis in Potatoes Experiment
The following experiment is a fun and easy way to see the effects of plant osmosis on a plant by
comparing two different potatoes placed in different types of water
These are the materials needed to view osmosis in action:
- 2 Potatoes
- 2 Plates
- Salt
- Water
- Knife
Methods:
Fill both of the dishes with water and add about two tablespoons of salt to one of the dishes.
Using the knife, cut the potato in half lengthwise. Then Place each piece flat side down in to one
of the plates of water.
Now simply let the two potato pieces soak in the water for a few hours. After this time has passed
flip each potato over and look for differences.
When looking at the potato pieces you can clearly see a difference between the two. Let’s take a
closer look at each of the potato pieces!
The potato slice that has been soaking in freshwater. Not much of a difference here, only that the
potato is a little more rigid then before. This is because there is the more salt and other dissolved
chemicals within the potato then the surrounding water. This means that the water will move into
the potato.
This potato slice that has been soaking in saltwater. This potato pieces looks substantially
different from the original and the other slice. It seems to have wilted, gotten very soft and
flexible. Why did that happen?
It has to do with a process called osmosis. The potato is made up of tiny, living units called cells.
Each cell is surrounded by a cell membrane which acts much as your skin does. It keeps the cells
parts inside and keeps other things outside, protecting the cell.
While this membrane stops most things, water can pass through it. The water tends to move
towards higher concentrations of dissolved chemicals. That means that if the water outside the
cell is saltier than the water inside, water will move from the inside of the cell to the outside. As
the water left the cell it was much like letting the air out of a balloon. As more and more of the
cells lost water, the slice of potato became soft and flexible.
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Formative Assessment(s):
Explain: Allows the learner to construct an explanation (claim  evidence  reasoning). The
teacher provides information in common terms to increase the accuracy of the explanation.
Diffusion Lab http://www.biologycorner.com/worksheets/diffusionlab.htm
Diffusion Lab
Introduction: In this lab you will observe the diffusion of a substance across a semi permeable
membrane. Iodine is a known indicator for starch. An indicator is a substance that chances color
in the presence of the substance it indicates. Watch as your teacher demonstrates how iodine
changes in the presence of starch.
Prelab Observations: Describe what happened when iodine came into contact with starch.
Procedure:
1. Fill a plastic baggie with a teaspoon of corn starch and a half a cup of water tie bag. (This
may already have been done for you)
2. Fill a beaker halfway with water and add ten drops of iodine.
3. Place the baggie in the cup so that the cornstarch mixture is submerged in the iodine
water mixture.
4. Wait fifteen minutes and record your observations in the data table.
5. While you are waiting, answer the questions.
Questions:
1. Define diffusion.
2. Define osmosis
3. What is the main difference between osmosis and diffusion
4. Why is iodine called an indicator?
5. Molecules tend to move from areas of _______ concentration to areas of ______
concentration.
What is in the Bag?
We’re going to think about concentrations now, which substances are more or less concentrated
depends on which one has the most stuff in it.
1. Is the baggie or beaker more concentrated in starch?
2. Is the baggie or beaker more concentrated in iodine?
3. Iodine solution: is the baggie or the beaker hypertonic?
4. Starch solution: is the baggie or the beaker hypertonic?
5. Which one is hypotonic in relation to starch, baggie or beaker?
Make Some Predictions
1. If the baggie was permeable to starch, which way would the starch move, into the bag or out of
the bag? ________
2. If the baggie was permeable to iodine, which way would the iodine move, into or out of the
bag? _______
3. If the baggie was permeable to iodine, what color would you expect the solution in the baggie
to turn? _______ What about the solution in the beaker? ___________
4. If the baggie was permeable to starch, what color would you expect the solution in the baggie
to turn? ________ What about the solution in the beaker? _________
5. Make a prediction about what you think will happen:
Data Table
Starting Color
Color after 15 minutes
Solution in Beaker
Solution in Bag
Post Lab Analysis
1. Based on your observations, which substance moved, the iodine or the starch?
2. How did you determine this?
3. The plastic baggie was permeable to which substance?
4. Is the plastic baggie selectively permeable?
5. Sketch the cup and baggie in the space below. Use arrows to illustrate how diffusion occurred
in this lab.
6. What would happen if you did an experiment in which the iodine solution was placed in the
baggie, and the starch solution was in the beaker? Be detailed in your description.
7. Why is it not a good idea to store iodine in a plastic bag?
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Formative Assessment(s):
Have the students use the Claim-Evidence-Reasoning model to explain this experiment.
Have them develop a testable question. The claim is the answer to that question.
Elaborate: Pushes learner understanding, building on current understanding to increase the
depth and breadth of understanding. Allow the learner to extend and apply the concepts,
processes, or skills. Allows learner to experience new situations to apply to their learning.
Additional Labs
1. HONEY, I SHRUNK THE CARROTS - Carrot Osmosis Activity
Background:
 Learner should know the main parts of a cell.
 Learner should understand particle movement.
Summary:
Students will use carrots as cell models and demonstrate diffusion and osmosis.
Students will measure and observe the changes in the mass and size of the carrot.
Materials:
 Two 400 mL beakers
 string
 measuring tape or meter stick
 salt
 distilled water
 triple beam balance
 carrots
Safety concerns:
Teachers and students, be sure to keep all Glass, Chemical, and Sharp
instrument Safety Rules that are specified by the teacher and in all general laboratory
experiences.
Student Procedures:
Carrot Experiment
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4.
Fill two beakers with equal amounts of water.
Add 15 g salt to one beaker and label it "Salt Water".
Cut a carrot in half. Tightly tie a piece of string two cm below the cut end of both pieces.
Place one carrot half (cut end down) in the "Salt Water" beaker. Place the other carrot
with cut end down in the "Fresh Water" beaker. Allow carrots to remain undisturbed for
24 hours. Students form a hypothesis. Remove carrots and observe them and the tightness
of the strings. Record data.
5. At the conclusion of your experiment, answer the following questions (realize that some
require deeper thinking than others?
 Did the thread become loose in fresh water or salt water?
 Did the thread become tight thread in fresh water or salt water?
 Did the carrot develop a soft texture in fresh water or salt water?
 Did the carrot develop a firm texture in fresh water or salt water?
 In which type of water did the carrot cells increase in cell size (freshwater or salt water?)
 In which type of water did the carrot cells decrease in cell size (freshwater or salt water?)
 Was there a loss of water by cells in fresh water or salt water?
 Did the cells gain of water in either fresh water or salt water?
Deeper thinking questions
 What was the purpose of having you tie thread on each carrot?
 In which kind of water did the carrot cells lose water?
o What evidence supports your conclusion?
 In which kind of water did the carrot cells gain water?
o What evidence did you use to determine this?
 What do you think would happen to human blood cells if they were placed in a beaker of
salt water?
2. CELL AND DIFFUSION LAB
Background:
 Learner should know the main parts of a cell.
 Learner should understand particle movement.
Summary:
Students will use bags as cell models and demonstrate diffusion.
Observations:
Have students observe the properties of iodine solution. (liquid, tan colored) Have students
observe what happens to the color of iodine as it comes in contact with starch in the form of
bread. (The iodine turns black in the presence of starch it is an indicator of starch.
How might a bag be like a cell? (It can hold things like a cell. The bag would be the cell
membrane.)
Materials:
For use by the class: Box of cornstarch and iodine solution
For each group of students: small plastic bags, small rubber, bands, 1 - cup measuring cup,
scissors, 600 mL beaker, access to warm and lukewarm water
Safety concerns:
Teachers and students, be sure to keep all Glass, Chemical, and Sharp
instrument Safety Rules that are specified by the teacher and in all general laboratory
experiences.
Student Procedures:
1. Add one teaspoon of cornstarch to 1 cup of water. Stir until the cornstarch is dissolved.
2. Pour the mixture into a small plastic bag. Wrap a rubber band around the top of the bag to seal
the bag.
3. Pour 100 mL of warm water into a 600 mL beaker.
4. Carefully place the bag with the cornstarch water into the 600 mL beaker.
5. Let it set for a few minutes and observe what happens.
6. Answer the following questions:
 Why did the water inside the bag turn black?
 What part of the cell is the bag like?
 Which process occurred, diffusion or osmosis?
 Did the starch move out of the bag? How do you know?
Extension:
Are there any other indicators that could be used to show the diffusion of particles across the bag
wall?
Does the temperature of the water affect how long it takes for the iodine to move into the cell?
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Formative Assessment(s):
Evaluate: Provides and opportunity for the learner to assess their own understanding and be
able to demonstrate the depth and breadth of that understanding to others. Teacher assesses the
learner’s level of understanding and mastery.
 Summative Assessment(s):
The student will design a poster using one of the labs above that they have already
completed. The poster will need to show the process of osmosis or diffusion as it occurred in
the experiment. Print out Osmosis or Diffusion Poster Scoring Guide.
Additional Resources:
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Text: Science Explorer: Cells and Heredity, pp. 32-37
Websites: http://www.biologycorner.com/bio1/diffusion.html#,
http://www.biologycorner.com/bio1/active.html,
http://www.biologycorner.com/worksheets/diffusionlab.htm,
Video:
Attachments:
Teacher Review: Include date, course, and name of teacher.
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