Osmosis Lab – using egg
Purpose: to model osmosis using an egg with the shell removed. This model will also help the student to
understand the terms Hypertonic, Hypotonic, and Isotonic.
Materials:
-
6 eggs with the shells removed
Vinegar
Plastic containers
Several solutions of various concentrations of sucrose
Tongs
Paper towel
Scales
Method:
Part 1:
1.
2.
3.
4.
5.
Weigh your 6 eggs with the shells and record in Data Table 1
Place your eggs in separate labelled containers
Cover each of the eggs with vinegar
Put a lid on it
Let it soak for 2 days
Part 2:
1. Gently remove the egg from the container and rinse it off with tap water to remove any shell
remaining
2. Weigh the egg and measure its circumference (being very very careful); record info in data table.
3. In Groups of 3, place the eggs in each of the sugar solutions and let them sit for 2 days.
4. Record your data in the class data table.
5. Set up your formal lab report.
At school _______________________________:
1.
2.
3.
4.
5.
6.
Remove the eggs from each solution and weigh and measure them
Record your data.
Eggs can go in the garbage, solutions down the sink
Clean up.
Enter your data in the class data table.
Complete your formal lab using the class data.
Questions you should answer in your conclusion:
These should NOT be presented in question format, but included in the body of your paragraph.
1. Define the terms hypertonic, hypotonic, and isotonic
2. Which solutions were hyper-, hypo,- and/or isotonic to the egg, how did you know (state examples
from the class data)
3. Draw three diagrams to explain the movement of water (osmosis) into or out of the egg to represent
the three main types of solutions.
4. In which of the solutions was the osmotic pressure the greatest. Explain what osmotic pressure is.
5. State sources of error.
6. How might you make this lab better?
Observations:
Data Table 1: Mass of eggs with shells
Egg #
1
Mass with Shells
Mass without shells
2
3
4
5
6
Table 2: Osmosis observations
Egg # and
Initial Mass
Solution []
1. Distilled
water
2. 0.5 M sucrose
3. 1.0M sucrose
4. 1.5M sucrose
5. 2.0M sucrose
6. 3.0M sucrose
Initial
Circumference
Final Mass
Final
Circumference
% Mass
Change
Table 3: Class Data
Egg # and
Average %
Solution []
Mass Change
1. Distilled water
2. 0.5 M sucrose
3. 1.0M sucrose
4. 1.5M sucrose
5. 2.0M sucrose
6. 3.0M sucrose
In the space below write any qualitative changes or observations that you noticed in your eggs or during your
experiment.
Calculations:
Calculate the % change in mass for each of your eggs:
(final mass – initial mass)
Initial mass
X 100
If you are taking a biology course, at some point you will have to do lab experiments. This means that you will
also have to complete biology lab reports.
The purpose of writing a lab report is to determine how well you performed your experiment, how much you
understood what happened during the experimentation process, and how well you can convey that
information in an organized fashion.
Biology Lab Reports: Formats
A good lab report has a format that includes five main sections. They are the introduction, methods and
materials, results, discussion and conclusion, and citation.
Keep in mind that individual instructors may have a specific format that they require you to follow. Please be
sure to consult your teacher about the specifics of what to include in your lab report.
Introduction:
The introduction of a lab report states the purpose of your experiment. Your hypothesis should be included in
the introduction, as well as a brief statement about how you intend to test your hypothesis.
To be sure that you have a good understanding of your experiment, some educators suggest writing the
introduction after you have completed the methods and materials, results, and conclusion sections of your lab
report.
Methods and Materials:
This section of your lab report involves producing a written description of the materials used and the methods
involved in performing your experiment. You should not just record a list of materials, but indicate when and
how they were used during the process of completing your experiment.
The information you include should not be overly detailed, but should include enough detail so that someone
else could perform the experiment by following your instructions.
Results:
The results section should include all tabulated data from observations during your experiment. This includes
charts, tables, graphs, and any other illustrations of data you have collected. You should also include a written
summary of the information in your charts, tables, and/or other illustrations. Any patterns or trends observed
in your experiment or indicated in your illustrations should be noted as well.
Discussion and Conclusion:
This section is where you summarize what happened in your experiment. You will want to fully discuss and
interpret the information. What did you learn? What were your results? Was your hypothesis correct, why or
why not? Were there any errors? If there is anything about your experiment that you think could be improved
upon, provide suggestions for doing so.
Citation:
All references used should be included at the end of your lab report. That includes any books, articles, lab
manuals, etc. that you used when writing your report.
You may NOT just list websites such as wikipedia or google as a citation.
Journals:
Author(s). Date. Article title. Journal title. Volume(issue):location
Example:
Mazan MR, Hoffman AM. 2001. Effects of aerosolized albuterol on physiologic responses to exercise in standardbreds.
Am J Vet Res. 62(11):1812–1817.
Books
Author(s). Date. Title. Edition. Place of publication: publisher. Extent. Notes.
Example:
Leboffe MJ, Pierce BE. 2010. Microbiology: laboratory theory and application. Englewood (CO): Morton Publishing
Company.
Websites and Other Online Formats
Title of Homepage. Date of publication. Edition. Place of publication: publisher; [date updated; date accessed]. URL.
Example:
APSnet: plant pathology online. c1994–2005. St Paul (MN): American Phytopathological Association; [accessed 2005 Jun
20]. http://www.apsnet.org/.
Example for more simple websites:
How stuff works: Osmosis. October 21 2008. [Oct 21 2008; accessed 2015 Oct 13].
http://science.howstuffworks.com/dictionary/biology-terms/osmosis-info.htm