EGG OSMOSIS LAB INSTRUCTIONS
READ THE INSTRUCTIONS COMPLETELY BEFORE YOU START
Part of your lab grade may be affected if you ask questions which are clearly addressed in these instructions, such as “How many eggs do I need?”
Purpose
Demonstrate the process of osmosis using the semi–permeable membrane of a chicken egg. Predict the isotonic point and an unknown concentration of sucrose solution based on graphed data.
Objectives
Demonstrate an understanding of homeostasis and its importance in the functioning of the human body systems (chapter 1)
Explain how the properties of water make it vital to homeostasis (chapter 2)
Compare the mechanisms by which substances enter and exit the cell (chapter 3)
Collect data and analyze the results of physiological experiments, using the Scientific Method
Materials
2 de–shelled eggs
2 beakers, each containing the same concentration of sucrose
Scale
Weigh Boat
Paper Towels
Timer (Set to 15 minutes)
Recorder (one person will write down the weights in a journal and then enters them into the group record)
Methods
First, you should prepare a chart like so (although you will also be adding your data to an Excel
spreadsheet that will be shared with the entire class):
Time (Min) Egg 1 Egg 2
0
15
30
45
60
75
1. Gently dry your de–shelled eggs.
2. Place the weigh boat on the scale and tare (0) the scale. Place egg #1 on the scale and record its
weight. Repeat this procedure for egg #2.
3. Place ONE egg into EACH beaker of sucrose solution and start your timer.
4. After 15 minutes, remove egg #1 from its beaker, dry it gently, and weigh it. Repeat this step for
egg #2. (Don’t mix up your eggs!)
5. Place your eggs back into their beakers and set your timer for another 15 minutes, then repeat
step 4.
6. Repeat steps 4&5 until you reach 75 minutes total. You should have six weights recorded for
each egg.
7. Record your data in the group data table on your instructor’s computer, in the appropriate
section for your sucrose concentration. This data will be shared with the class.
NOTE: The whole experiment consists of performing this procedure for various concentrations
of sucrose. Your lab group is just one ‘treatment’ group (or you may be the control). There is
also one group working with an ‘unknown’ concentration. You must use two beakers of the
same concentration (replicates) in order to ensure reliability and account for error.
Lab Report Instructions
FORMATTING:
1. Single–spaced, 1” margins on all sides, page numbers
2. Size 12 point font in Time New Roman or Arial
3. Use bold, numbered headings for each section
4. Use complete sentences in paragraph form
5. You are not graded on the ‘right’ result—the data is what it is. You are graded on your analysis of
the result in relation to your hypothesis.
6. Submit to Assignments folder on D2L by due date
LAYOUT:
1. Introduction
a. Define osmosis in your own words
b. Explain how osmosis is being demonstrated in this experiment in your own words; state this in
the form of the ‘purpose’ of the experiment
2. Hypothesis
a. State hypothesis for experiment (what will happen and why, based on the intro?)
3. Methods
a. State specific methods used during experiment, including (be thorough)…
b. How were eggs prepared (vinegar w/ 3% acetic acid)
c. What were the %’s of sucrose used
d. How long were eggs in sucrose and when were they weighed
e. How was data collected
4. Results
a. What was the concentration of the unknown?
i. Explain how you determined this
b. What was the isotonic concentration?
i. Explain how you determined this
c. Write up what you found in Tables 1–3 & Graphs 1–7 in sentences
d. Insert Tables #1–3
i. Weights vs. Time
ii. Change in Weight vs. Time
