Lesson Title: Observing Osmosis in a Chicken Egg
Discipline Focus: Introductory Biology
Grade level: 10th Grade
Length of lesson: Two 50 minute class periods separated by 24 hours
Stage 1 – Desired Results
Content Standard(s):
Minnesota Academic Standards in Science Code: 9.4.1.2.5
General standard indicates students will understand that cells and cell structures have specific
functions that allow an organism to grow, survive and reproduce.
Understanding (s)/goals
Students will understand:
1. Concept of diffusion
2. Internal – external interaction
between a cell and its surroundings.
Essential Question(s):
What is the function of a selectively
permeable membrane to a cell and how
does it work? How does this relate to
homeostasis of the cell?
Student objectives (outcomes):
Students will be able to:
Explain the process of diffusion and apply this to the movement of molecules into and
out of a cell mediated by a selectively permeable membrane.
Stage 2 – Assessment Evidence
Other Evidence:
1. Students are asked to develop
A worksheet will accompany the activity in
hypotheses based on prior
which they will be asked to represent their
knowledge of diffusion.
data with a graph and use this to interpret
2. Both basic and thought questions
and report their results.
will be asked on the worksheet to
evaluate their understanding.
3. Students will be asked to verbally
explain what they are observing.
4. The material will again appear on a
unit test to evaluate their retention
of the material.
Stage 3 – Learning Plan
Learning Activities: see following pages
Performance Task(s):
Name __________________
Period_________________
Observing Osmosis in a Chicken Egg
By: Michael Lynch (adapted from several sources)
10th Grade Biology
Duluth East High School
Objectives:
 Learn vocabulary associated with diffusion
 Observe osmosis across a selectively permeable membrane
 Identify unknown solution
 Develop good laboratory practice
 Report data visually using a graph
Vocabulary:
1. Osmosis
2. Selectively Permeable
3. Solute
4. Solvent
5. Solution
6. Hypotonic
7. Hypertonic
8. Isotonic
Experimental Setup
Chicken eggs have been soaking in vinegar for the last two days to have their shells
removed (dissolved away) and have been placed in a 20% sucrose solution.
How does this work?
When you submerge an egg in vinegar, the shell dissolves. Vinegar contains
acetic acid, which breaks apart the solid calcium carbonate crystals that make up
the eggshell into their calcium and carbonate parts. The calcium ions float free
(calcium ions are atoms that are missing electrons), while the carbonate goes to
make carbon dioxide—the bubbles that you see.
The eggs are still surrounded by a thin – selectively permeable – shell membrane. Be
careful these are fragile. (If you break an egg you will be cleaning up the classroom)
You will be placing your eggs into four different concentrations of sucrose: 0% (distilled
water); 20% sucrose, 40% sucrose, and an unknown sucrose solution.
1) Based on this setup and what you know about diffusion develop a hypothesis
explaining the movement of water molecules across the semipermeable membrane
and the resulting weight change of the egg in each of the solutions. Include what
type of solution do you think each of these are (hypotonic, hypertonic, isotonic)
a) 0% (distilled water)
b) 20% sucrose
c) 40% sucrose
2) Will the eggs gain or lose weight in solutions below 20 %?
3) Will the eggs gain or lose weight in solutions above 20%?
4) We will have a couple extra eggs. Based on what you know about osmosis and the
experimental setup, propose a treatment for one or all of the extra eggs. Each
group will decide on this extra treatment and propose it to your instructor.
Depending on the number of extra eggs we will perform some or all of these
proposals.
Day 1
You will be broken into groups of five for this exercise.
In your group obtain four shell-less chicken eggs from your instructor. Handle them
gently so the shell membranes remain intact. (Remember you will clean up any mess)
Gently dry each egg and weigh them (record in the table below, under initial weight)
Place one egg in each of the sucrose treatment bins.
Your insturctor will help you set up your special treatment.
Day 2
Gently remove your egg from each solution
Carefully dry each egg and weigh them. Record your results in the following table.
Initial Weight
(grams)
Final Weight
(grams)
0% Sucrose
20% Sucrose
40% Sucrose
Unknown
Sucrose
Special
Treatment
Post lab questions
1. Which solution(s) was hypotonic to the egg? Why?
2. Which solution(s) was hypertonic to the egg? Why?
3. Which solution(s) was isotonic to the egg? Why?
Weight Change
(grams)
4. If an egg was placed in a 50% sucrose solution, would it lose, gain or stay the
same weight? Why?
5. Based on the data you collected roughly what percent sucrose solution was your
unknown? Explain your answer.
6. Why do grocery stores spray their fresh produce with water? What kind of water
do you think they are using?
7. If a shipwrecked crew drank salt water, they could die. Explain why.
8. What happened to the weight of the egg in your special treatment? Does this
mean it was a hypertonic, hypotonic, or isotonic solution?
9. What is one question you have about osmosis after this lab?
10. Using your knowledge of the different types of graphs and when to use them;
make a graph of your data. Be sure to label the x-axis and y-axis and include a
descriptive title.