Osmosis, Diffusion & Active Transport
L/O: To review understanding of diffusion, osmosis and active
transport and how to investigate the process of osmosis
Starter Recap:
Write your own definition of
diffusion on the whiteboard
Extension: Explain how nutrient
get from inside the small
intestine to the blood stream
Success Criteria:
A* - Suggest how to investigate the rate
of osmosis
A – Explain the process of osmosis and
its primary functions, and how these
differ from diffusion and active
transport
B – Describe
the steps inEnquirers
osmosis
CORE: Independent
C – State what is involved in diffusion
KEY WORDS
Osmosis Solute
Partially
permeable membrane particle
diffusion concentration gradient
Active transport
If you open a can of
pop, gas particles
spread out into the air.
This is another
example of diffusion.
Definition:
Diffusion is the movement of particles
from an area of high concentration, to
an area of lower concentration.
Osmosis
Solute molecule
Many water
molecules
Weak Solution
What will
happen in
this
situation?
Fewer water
molecules
Strong Solution
Partially permeable membrane
What will
happen in
this
situation?
Osmosis in blood cells
Liquid is more
concentrated
Liquid and cell
cytoplasm are the
same concentrations
Inside cells are
more
concentrated
Cells become flaccid when water moves out of them.
Cells become turgid due to water pressure when water moves
into them
Osmosis vs. Diffusion
Similarities
Differences
What are the similarities and differences between the two?
Osmosis vs. Diffusion: PEER ASSESS
Similarities
Differences
Movement of molecules
from areas of high
concentration to low
concentration
Osmosis is movement of
water only/ Diffusion any
small molecules
Movement of small
particles/molecules
Both found in all plant and
animal cells to move
substances in and out
Osmosis moves across a
partially permeable
membrane/ Diffusion moves
more generally
What are the similarities and differences between the two?
How to kill a slug?
QUESTIONS:
Using your knowledge of
osmosis explain how to remove
the slugs that are eating
Farmer Gile’s lettuces!
Include an explanation using
the following key words:
• Concentration gradient
• Osmosis
• Diffusion
• Solute
• Particle
Active Transport
This is when substances are absorbed against their
concentration gradients. This uses energy.
Explain how this process uses active transport and
where this might be found.
OSMOSIS Recap
Net flow of water is from areas of high concentrations of
water molecules to low concentrations of water molecules
Water molecules
move in both
directions
Sugar cannot
cross the
partially
permeable
membrane as
they are too
large
Net flow of water is from dilute solutions to concentrated
solutions
Cold Call Questions!
1. What is an independent variable?
2. What is a dependent variable?
3. What is a systematic error?
4. What makes something reliable?
5. What makes something valid?
6. What is diffusion?
7. Give an example of diffusion?
8. What is osmosis?
9. What is different about osmosis and diffusion?
10.Name one place in the body where diffusion happens?
11. What happens to a red blood cell if it is placed in a salt
solution?
12.What happens to a red blood cell if placed in a pure water
solution?
THE EXPERIMENT
Method:
1. Weigh 4 different 1cm3 of potato cube on
scales (RECORD EACH WEIGHT)
2. Place each potato chip into a boiling tube
with different sugar solutions
3. Leave for 20mins and complete questions
while waiting!
4. Remove chips, dry and re-weigh.
5. Calculate the change in mass of each chip
in each concentration
THE EXPERIMENT
Label the
potato
boiling
tube so
you know
which cube
is which!
Method:
Complete
the
workshe
et while
you are
waiting
for the
results!
DRAWING A TABLE
Solution sugar
concentration (%)
Initial Mass (g)
Final Mass (g)
Change in mass (g)
Change in mass of potato (g)
INTERPRETING RESULTS
Sugar solution (%)
Plot a graph of your results and explain what happens at
each stage
• Success Criteria:
• A* - Suggest how
to investigate the
rate of osmosis
• A – Explain the
process of osmosis
and its primary
A* functions,
and how
these differ from
diffusion and
active transport
• B – Describe the
steps in osmosis
• C – State what is
involved in
diffusion
What have I learnt?
On the exit ticket complete what
target you archived you know you
achieved (i.e. what can you do).
Look at the success criteria to help
you
5 min