Key Question: How do you think things like
water and food, which cells need to live, get
into and out of cells?
Initial Thoughts:
What does “concentration” mean? For example:
the concentration of salt in sea water.
Concentration means: The number of “particles”
in a given space. Which is more
concentrated?
OR
• Perfume
• Food coloring and beaker
• Food coloring and graduated cylinder
• Make a prediction.
• Why did you predict what you did?
• Diffusion is the natural
movement of any molecule
from high concentration
(where there’s lots of them)
to low concentration (where
there’s not as much)
until they are equally spread
out.
• Diffusion of water from high to low
concentration
• Osmosis – the movement of water molecules
from high concentration to low concentration
• Movement from high to low
concentration until they are
spread out equally in all areas
• Movement of ANY molecule,
while….
• Osmosis is the diffusion of
WATER.
Diffusion is a slow
process because it
relies on the random
movement of atoms
and molecules.
• This is how things like oxygen, food, and water
get transported into and out of cells.
• http://molo.concord.org/database/activities/2
23.html
• Digital projects:
– Name your file your LAST NAME, FIRST NAME, PER
1, 2, OR 3.
– Save to S:/ drive, Teachers, Mrs. Mackenzie, Inbox,
Cell City Project, your period.
Today: Set up Egg Lab
• Osmosis – the movement of water molecules
from high concentration to low concentration
• Movement from high to low
concentration until they are
spread out equally in all areas
• Movement of ANY small
uncharged molecules
• Osmosis is the diffusion of
WATER.
• Hypotonic:
it causes it to swells up
(think Hypo = Hippo)
• Hypertonic:
it causes it to shrivel up
(Think hyper skinny kid)
• Vinegar is an acid that will dissolve the hard
shell, leaving only the thin membrane around
the egg “cell”.
• Water is small enough that it can enter or
leave through the egg membrane.
(it is selectively permeable).
Variables:
Manipulated Variable:_____________
Responding Variable:______________
Controlled Variables:______________
Variables:
• Manipulated Variable: Type of liquid
• Responding Variables: Weight of egg and
Volume of liquid
• Controlled Variables: same egg, same amount
of time in liquid, same amount of liquid
#1 Testable Question: What will happen when
an egg is soaked in corn syrup?
Hypothesis: If an egg is soaked in corn syrup, then
the egg will....because…..
#2 Testable Question: What will happen when an
egg is soaked in colored water?
Hypothesis: If an egg is soaked in colored water, then
the egg will....because…..
1. Explain why diffusion and osmosis are important
to cells.
2. Why do grocery store owners spray fresh fruits
and vegetables with water? Explain using what
you learned about osmosis.
3. If a shipwrecked crew drinks sea water, they will
probably die. Why?
Write a summary of the Egg Lab. Remember to:
1. restate your hypotheses (there were 2 in this
one)
2. Tell if it was supported or not.
3. Use your data to back up #2
4. Explain your data using the principles behind
Osmosis/Diffusion. Was the corn syrup and
colored water hypotonic or hypertonic?
5. Further thoughts, improvements, extensions,
etc.
• Draw what happens when a cell is placed in
sea water, using arrows to show the direction
water is moving (in or out of the cell).
• Cells use diffusion and osmosis to get things
like food & water into and out of cells.