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• What is osmosis?
• What happened when we put our gummi
bears into water?
• WHY did this happen?
Objectives
• To understand what happens during
osmosis in regards to osmotic
pressure.
• To compare and contrast hypertonic,
hypotonic, and isotonic solutions.
• To explain different real life applications
of these solutions.
Osmotic Pressure
• What is osmosis?
• Whichever has MORE water (either the
solution or the solution inside the cell)
is going to be the one to have a higher
osmotic pressure and the water will
flow in the direction of lower osmotic
pressure.
“Tonicity”
• The measure of osmotic pressure
• There are 3 types of solutions in
regards to tonicity
– Isotonic
– Hypertonic
– Hypotonic
Quick Refresher!
• What is a solution?
• Solute vs. solvent?
• Example?-
Isotonic Solutions
• Same amount of solute outside the
membrane as there is inside.
• Effect: NOTHING 
Plant Cell
Blood Cell
11,397x
Hypertonic Solutions
• Solution contains MORE SOLUTE than
the cell, water flows out of the cell.
• Effect: cell shrinks/shrivels 
“Plasmolysis”
“Crenates”
Hypotonic Solutions
• Solution contains LESS SOLUTE than the
cell, water flows into the cell.
• Effect: cell swells or bursts! /
•
(remember the grocery store misters?)
Animations
• http://www.biologyjunction.com/tonicity%2
0animations.htm
High or low Solute?
Cell in ________
Solution
H2O
H 2O
Cell in ________
Solution
H 2O
H 2O
Cell in ________
Solution
H 2O
H 2O
Real Life Application
• Turn to the person sitting next to you. In the
next few slides you will see real life
scenarios using the 3 types of solutions we
have discussed. For each scenario you and
your partner should determine what type of
solution is being described as well as what
will happen.
Scenario 1
A salt water fish is put into a
freshwater aquarium.
• What type of
solution is the
freshwater?
• What is going to
happen to the cells
of the fish?
Scenario 2
A patient is given an IV, which contains the
perfect balance of glucose
• What type of
solution is in the
IV?
• What is going to
happen to the cells
of the human?
Scenario 3
Your garden is infested with slugs so
you go around pouring salt on them
• What type of
solution is this salt?
• What is going to
happen to the cells
of the slug? (don’t
do this to the poor
slugs )
Practice
• By yourself or with a partner (anyone),
work on the diffusion problems.
• First try to do this by yourself, then verify
your answers with a partner. Try to help
each other. If you are confused, raise your
hand and I will come help you!!
• If you finish early, try to answer the “Think
about it” questions on my desk! If you don’t
finish, please finish it for homework.
3-2-1 Exit Slip
• On a SEPARATE sheet of
paper…
• List 3 things you learned today
• List 2 things you are confused
about
• List 1 thing you found interesting
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