Download High concentration

Diffusion and Osmosis
Notes
Objective: You will be able to explain
diffusion and osmosis and give an
example for each one.
Itinerary:
1. PowerPoint (definitions)
2. Teacher demostrations
The Plasma Membrane and
Homeostasis
Homeostasis – Maintaining
a Balance
• Cells must keep the proper
concentration of nutrients and
water and eliminate wastes.
SO HOW DO THINGS GET INTO THE
CELL?
The cell doesn’t have a mouth, so
particles have to go through the cell
membrane!
Word
1. Cell
membrane
Definition
Surrounds cell
Semipermeable:
Lets certain
things in and
out of cell
Picture
Everything a cell needs to come in or
go out has to pass through cell
membrane
Food
molecules
Carbon
dioxide
Oxygen
molecules
Wastes
Water
molecules
The cell membrane has little spaces where
things can just slip right in or out of the cell.
So….
Some substances are so small that
they can slip between the membrane
molecules to enter or leave the cell.
Imagine a jar full of marbles…
Can you pour some sand into the jar?
The sand will fill up the space in
between the marbles…that’s how
some materials can get through the
cell membrane.
What does passive mean?
This lady is passive!
Word
2. Passive
Transport
Definition
No energy to
move materials
Examples:
Diffusion and
Osmosis
Picture
Word
3. Diffusion
Definition
When particles
move from an
area of high
concentration to
an area of low
concentration
HIGH TO LOW
Picture
Passive Transport – Diffusion
Familiar examples of diffusion:
• A skunk’s odor spreads through the
neighborhood
• A spilled bottle of perfume fills the air with
a strong scent
• Food coloring mixes through a beaker of
water
No energy is needed for oxygen to
diffuse into a cell.
• High concentration of
oxygen outside of cell
• Low concentration of
oxygen inside the cell
• Diffusion of oxygen into
cell
• Equal concentration of
oxygen outside and
inside cell
No energy is needed for carbon
dioxide to diffuse out of the cell.
• High concentration of
carbon dioxide inside of cell
• Low concentration of carbon
dioxide outside the cell
• Diffusion of carbon dioxide
out of cell
• Equal concentration of
carbon dioxide in and
outside cell
Word
4. Osmosis
Definition Picture
The diffusion of
water across a
membrane
HIGH TO LOW
LOTS OF WATER
TO LESS WATER
Osmosis – What is happening in
this animation?
What happened to the celery?
Is this diffusion or osmosis?
This celery is
wilted, so we
put it into
water.
Less water IN celery
It is OSMOSIS!
Water flowed into celery!
Your blood is similar to sea water in
the amount of salt it contains.
What do you think
would happen to one
of your red blood cells
if you placed it in pure
water?
Fresh water will flow
into the cell and it will
burst!
Word
5.
Equilibrium
Definition
when the molecules
of a substance are
spread out evenly
throughout the
Space
- Osmosis and
diffusion will
continue until
particles are
equal
Picture
EXIT SLIP
1. Give definition and an example of
diffusion (you may have seen some today in
class)
2. Give a definition and an example of
osmosis.
3. What is passive transport?
4. What is equilibrium?