BIO 113
Osmosis in Eggs Lab
Name________________________Class____Date________
A cell model using a decalcified egg will be placed in sucrose solution and distilled water. Most
cells are tiny—much too small to see without the help of a microscope. In contrast, an unfertilized
chicken egg is a giant cell. In this investigation, you will see that water can cross the cell
membrane surrounding an egg, but the direction of movement depends on the type of liquid
surrounding the egg. When water moves across the cell membrane, the egg changes in size and
appearance.
The initial mass of each egg will be recorded, and measured again every 5 minutes. Changes
in mass will be recorded in the data table.
1. Record results in the data table:
Mass change of egg placed in sugar solution and distilled water
Mass of egg in grams after time period
Solution
Sucrose
start
5 min.
10 min. 15 min. 20 min. 25 min. 30 min.
Distilled
water
2. Calculate the % loss or gain in mass for each egg. Show your work
% change = final mass – initial mass/initial mass X 100%
Sucrose:
Distilled water:
3. Graph the data from the table on the graph paper provided, and attach to this paper.
Reflect on the results of the demonstration, and review your data table and graph.
Answer the lab review questions on this page.
Review Questions
Consider each part of the question, and write complete answers. This sheet and the
graph will serve as the notes needed to complete the lab assignment on Blackboard.
4. What did the egg without a shell represent?
5. Describe and explain what happened to each egg over time when placed in the
following solutions:
a. Tap water
b. Sugar solution
6. Explain why the above results were observed. Include the terms diffusion, osmosis,
hypertonic, and hypotonic in your answer.
7. Why is it important for each cell to be surrounded by a cell membrane that can prevent
large molecules from leaving the cell?
8. The cell membrane allows some small molecules like oxygen to cross. Why is it
important for oxygen to be able to cross the cell membrane?