• Print slide 22 per student
• Diffusion practical- agar cubes
• Demo- potassium permanganate / starch in visking tubing
Behaviour targets:
1. Remain silent when the teacher is
talking.
2.Stay on task throughout the lesson.
3. Speak to staff and other students in a
polite way.
4.Refrain from unnecessary contact
with others.
DO THIS NOW…
Compare the
diagram to a typical
animal and/or plant
cell.
Are there differences?
Are there similarities?
04/05/2024
Learning Objectives
Understand how particles move by diffusion and why it is important for living things
Success Criteria –
1-4: state that diffusion is the spreading of the particles of any substance in solution,
or particles of a gas. list the factors that affect the rate of diffusion. write a simple
hypothesis.
5-6: predict which way substances will move across a cell membrane. explain why
surface area affects the rate of diffusion. write a hypothesis using scientific
knowledge.
7-8: explain how temperature and concentration gradient affects rate of diffusion.
write a hypothesis using detailed scientific knowledge and explain how it could be
tested.
Discuss…
What do cells need?
Water
Hormones
Oxygen
Glucose
Urea
Amino acids
Carbon dioxide
What do cells need to get rid of?
Discuss…
How do substances, such as oxygen and
carbon dioxide, get into and out of cells?
Key Concept
• In order for the cell to carry out the many chemical
reactions it needs to, substances must enter and leave
the cell.
• This happens in the following 3 ways:
New information- Diffusion
• Diffusion is a natural process that
happens all around us.
• It is simply where molecules spread
out from each other.
• We say that they are moving from a
high concentration to a low
concentration.
• Dissolved substances and gases can
move into and out of cells across the
cell membrane by diffusion.
New information- Diffusion
Demonstrate understanding
Task: Copy and complete the definition for diffusion.
Diffusion is the net movement of
Diffusion is the net ______________ of
particles from a region of high
_______________ from a region of _______
concentration
region
of low
___________
to a regionto
of a
________
____________.
concentration.
High
Particles Concentration Movement Low
Practical demo- Diffusion in action
When you can smell the
perfume hold up your
hand!
Task: Draw a particle diagram to explain what is
happening during diffusion.
Discuss…
Dissolved substance move into and out of your cells by
diffusion across the cell membrane.
How could you increase the
rate of diffusion?
End
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Practical activity-Investigating diffusion
You are going to in investigate the factors that affect the rate of diffusion
Experiment 1:
Remember to record your results accurately
How does temperature affect the rate of
diffusion?
Experiment 2:
Can diffusion occur across a membrane?
20
minutes
Practical activity-Investigating diffusion
You are going to in investigate the factors that affect the rate of diffusion
Remember to record your results accurately
https://phet.colorado.edu/sims/html/diffusion/latest/diffusion_all
.html
What happens when the temperature increases?
What happens when it cools?
What happens when you increase the concentration of particles?
What happens when you decrease it?
New information- Rates of diffusion
Concentration
In general, the greater the
difference in
concentration, the faster
the rate of diffusion. The
difference between two
areas of concentration is
called the concentration
gradient.
Surface area
The larger the
surface area the
faster the rate of
diffusion.
Temperature
An increase in
temperature means
the particles in a gas
or a solution move
around more quickly,
so diffusion takes
place more rapidly as
the random
movement of
particles speeds up.
New information- Rates of diffusion
New information- Rates of diffusion
New information- Rates of diffusion
Demonstrate understanding
Task: List three things that can affect the
rate of diffusion.
The rate of diffusion is
affected by the difference in
concentrations, the
temperature, and the available
surface area.
New information- Diffusion in living organisms
Dissolved substances move into and out of cells by diffusion across the cell
membrane. These include:
• simple sugars, such as glucose
• gases such as oxygen and carbon dioxide
• Waste products, such as urea from the breakdown of amino acids in your
liver.
Task: over the next few slides you will be shown some examples of
diffusion in living organisms. Annotate the diagrams provided with some
brief notes to explain what is happening.
New information- Digestive system
Digested food products move from the gut cavity to the
blood in the capillaries of the villi. The food products are in
higher concentration in the small intestine.
capillary network
Villi
small intestine
blood vessels
New information- Respiratory system
Oxygen moves from the air space in the alveoli to the blood
vessels around the lungs....
There is a large amount of
oxygen in the alveoli as it
is breathed in. There is a
small amount of oxygen
in the blood vessel as it
gets transported around
the body.
deoxygenated blood
(from body tissues)
capillary
air in/out
alveolus
oxygenated
blood (to body
tissues)
red blood cell
New information- The placenta
The placenta is an organ that
develops in the uterus during
pregnancy. The umbilical cord
connects the placenta to the
foetus.
Blood from the mother is high
in O2 but low in waste. Blood
from the foetus is low in O2
but high in waste.
umbilical
cord
blood to mother
• low in O2
• high in CO2/waste
blood from
mother
• high in O2
• low in CO2/waste
New information- Nervous system
A synapse is a junction between two nerve cells across
which electrical signals must pass.
Chemical
messages diffuse
Synapse
across the gap.
Chemical message
Moving from an
Nerve impulse
area of high
concentration to
low concentration.
New information- Stomata
Carbon dioxide diffuses
into the plant through the
stomata.
During photosynthesis
CO2 is used so the level of
CO2 inside the leaf is low.
Demonstrate understanding
Task: Describe two examples of diffusion
occurring with the body.
Any relevant examples: Food diffusing
out of the gut into the bloodstream,
oxygen diffusing into the bloodstream
form the lungs, carbon dioxide diffusing
into the lungs from the bloodstream.
Review and reflect
Which outcome did you reach? What skills do you do well?
What could you do to progress even further/ reach the next
outcome?
1-4: state that diffusion is the spreading of the particles of any substance in
solution, or particles of a gas. list the factors that affect the rate of diffusion.
write a simple hypothesis.
5-6: predict which way substances will move across a cell membrane. explain
why surface area affects the rate of diffusion. write a hypothesis using scientific
knowledge.
7-8: explain how temperature and concentration gradient affects rate of
diffusion. write a hypothesis using detailed scientific knowledge and explain how
it could be tested.
For printing……
capillary network
Villi
deoxygenated blood
(from body tissues)
capillary
small intestine
blood vessels
umbilical
cord
blood to mother
• low in O2
• high in CO2/waste
blood from
mother
• high in O2
• low in CO2/waste
air in/out
alveolus
oxygenated
blood (to body
tissues)
red blood cell