BIO115 Lab3
BIO115 Lab3
BIO115 Lab3
I. Introduction
Cells have an outer covering called the cell membrane. This membrane is selectively
permeable; it has tiny pores or holes that allow objects to move across it. The cell membrane
controls what moves in and out of the cell. Food and oxygen move into cells across the cell
membrane through the process of diffusion. Diffusion is movement of a substance from an
area of high concentration to an area of low concentration. Osmosis is a special type of
diffusion; it is the diffusion of water across a selectively permeable membrane. Osmosis occurs
when water moves from an area where it is more concentrated to an area where it is less
concentrated.
II. Objectives
The main objective of this laboratory is:
• To be able to soak egg in various liquids and observe how the size of the egg changes
as it gains or loses water.
III. Materials
• Raw egg
• Vinegar
• Distilled water
• Tap water
• Salt
• Sugar
• Paper cups
IV. Procedure
1. Prepare the 5 raw egg and 5 paper cups.
2. Measure first the size of the raw eggs.
3. Pour the various liquids (vinegar, salt with distilled water, tap water, sugar with
distilled water & distilled water) into the paper cups.
4. Put the raw eggs in the paper cups.
5. Wait for 3 days then observe.
V. Pre-Lab Questions
1. What do you think would happen to a shell-less egg if water passed into the egg through
the membrane?
I think the shell-less egg would break as the water passed through the membrane.
2. What do you think would happen to a shell-less egg if water passed out of the egg
through the membrane?
I think the shell-less egg will let water move in but the proteins will stay.
3. What substance must pass through the shell and membrane in order for a chick to
develop correctly?
Oxygen must pass through that came from the air sack and it replaces with carbon
dioxide.
4. What would happen to the developing chick if the egg membrane did not work
correctly?
The chick will either not develop or has abnormalities because egg membrane protects
the egg from bacteria and prevents the moisture from leaving the egg too quickly.
VI. Hypothesis
Predict how the egg will respond when it is soaked in:
1. Vinegar
The eggshell will soften because vinegar is acidic as it will absorb the acid and break down
the shell.
2. Salt Water
The egg will float.
3. List some liquids that you would like test and soak the eggs in.
I would like to test it on coke, baking soda, and milk.
VIII. Questions
1. Explain how the vinegar was able to remove the eggshell.
The vinegar was able to remove or soften the eggshell is because of the acid that the vinegar
contains. Since eggshell are made of calcium carbonate, it eventually absorbs the acid then
breaks down the eggshell.
2. When the egg was placed in the solutions (water, sugar, salt, vinegar) in which direction
did the water molecules move?
Of course, the water molecules moved into the egg.
3. On what evidence do you base this?
Since the egg was soaked into the different liquids for 3 days, the egg size will increase or
decrease.
4. How do you explain the volume of liquid remaining when the egg was removed from
the syrup?
When I saw the volume of the liquids lessen, this is because the liquids were absorbed into
the egg.
5. When the egg was placed in the water after being removed from the salt and sugar
solution, in which direction did the water move?
When the egg was placed, it moved into the egg.
6. Why did the water molecules travel better inside the cell that the other solution
molecules?
When the water moves through the membrane in osmosis, this is because of the balanced
concentration that the membrane contains, as the solute moved to balance the concentration
on both sides of it.
IX. References
Scientific American (2012). Porous Science: How Does a Developing Chick Breathe Inside
Its Egg Shell? Retrieved from https://www.scientificamerican.com/article/bring-science-home-
chick-breathe-inside-
shell/#:~:text=As%20the%20developing%20chick%20grows,to%20allow%20this%20to%20hap
pen
4-H Virtual Farm. The Parts of the Egg. Retrieved from
https://www.sites.ext.vt.edu/virtualfarm/poultry/poultry_eggparts.html