Respiration
Lornshill Academy Biology Department
Respiration is defined as “the controlled release of energy
from food molecules within cells”
Animals eat food as a source of energy.
This food is then digested by enzymes into
small, soluble molecules which can be
transported into cells.
The cell then releases energy from these
molecules by respiration.
Is the invisible man in this room?
Is there any energy in this peanut?
Comparing energy contents of different food types
thermometer
Boiling tube
5 ml water
food
spike
Variable changed
Variables the same
Type of food
Volume of water
Starting temperature
Weight of food
Distance food - water
These have to be kept
the same to make the
comparison fair
Results
Type of
food
Peanut
(fat)
Wotsit
(carbohydrate)
Egg white
(protein)
Starting
Final
Temperature
temperature temperature rise
Degrees C Degrees C Degrees C
Conclusion –
_____________ and ______________ contained much
more energy than ____________.
‘identify sources of error in experimental design and
suggest improvements’
Sources of error -
Suggested improvements -
‘identify sources of error in experimental design and
suggest improvements’
Sources of error Food not completely burned
Heat escapes up the side of the tube
Suggested improvements Re-ignite food or add oxygen
Use flat bottomed tube or beaker
Food molecules do not contain the same
amount of energy.
•Fats contain most energy
•Carbohydrates are also good energy
sources
•Proteins contain very little energy - their
main importance is as body building
materials.
Cells use the energy they release from
foods for a variety of purposes •movement - e.g. muscle cells
•division - e.g. bone marrow cells
•heat production - e.g. liver cells
•building products (synthesis
reactions) e.g. liver cells, cells making
digestive enzymes
The overall equation for respiration is -
glucose + oxygen
(raw materials)
CO2 + water
+ ENERGY
(products)
CO2
(waste
water
products)
There are a series of standard
experiments to show that each of the
materials is actually involved in the
process of respiration.
How can you show that CO2 is produced ?
How can you show that oxygen is used up ?
How can you show energy is produced ?
A demonstration will
be set up to
demonstrate that
energy is produced
during respiration.
Germinating
seeds
Dead seeds
Two flasks are set
up; one with
germinating seeds,
the other with dead
seeds.
The dead seeds are
a control. They are
not respiring, so
they give a result
to compare the
respiring seeds
with.
Germinating
seeds
Dead seeds
Some of the energy
produced in
respiration is in the
form of heat.
The temperature of
the germinating
seeds rises over a
few hours. There is
no change in the
dead seeds.
rise
Germinating
seeds
Dead seeds
We can conclude
that respiration
has resulted in the
release of heat
energy.
Demonstrating heat production by respiration
Germinating seeds
Dead seeds
Seeds
Cotton
wool
Thermometer
Results
Dead seeds
Starting temp.
Final temp.
Temp. rise
Conclusion :
Respiring seeds
My baby version
tin
insulation
Barley
seeds
Boiling
tube
Thermometer
Recording- Write a suitable title and use stencils to
draw a diagram of how the experiment was set up.
Answer Why the cotton wool stopper?
Why the insulated tin?
Why one with no seeds?
Draw a results table and write a conclusion for the
experiment.
•Compare your results with a group who used a
different mass of seeds.
•Write a conclusion to state how the mass of the
seeds affects the rise in temperature.
Respiration summary –
1. Write a definition of the term ‘respiration’.
2. Choose the correct phrase to copy and complete the
sentence ‘Respiration takes place in animals / plants / all living
cells.’
3. Respiration is a series of chemical reactions, each
controlled by an enzyme. From your knowledge of
enzymes, predict how temperature would affect the
rate of respiration.
4. Complete the following sentence –
‘If the mass of the living tissue is increased, the rate of
respiration will ...’
5. Write a word equation for respiration in living cells.
_______+______
________+________+ energy
Respiration summary –
1. The controlled release of energy from food in cells.
2. ‘Respiration takes place in all living cells.’
3. Respiration will take place slowly at low temperatures,
will speed up as conditions become warmer, and stop
when conditions become too hot, denaturing the
enzymes.
4. ‘If the mass of the living tissue is increased, the rate of
respiration will increase.’
5.
Glucose + oxygen
carbon dioxide + water + energy
“Would you like oxygen with
that, Sir?”
What do we know?
•For cells to do work, they need energy
•This energy is usually provided in the form
of glucose, the main product of digestion
•Cells break down the glucose to release
energy
•This process needs oxygen
•This is aerobic respiration
What do we know?
•Glucose +oxygen -> CO2 + H20 +energy
•This is complete breakdown of glucose
•The energy is used by the muscle to
produce movement and to build new
chemicals, but heat energy is also
produced.
What do we know?
•Yeast can break down glucose
anaerobically (without oxygen).
•Anaerobic respiration is incomplete
breakdown of glucose, so produces less
energy.
•Glucose -> CO2 + alcohol (ethanol)
+energy
Glucose is broken
down to carbon
dioxide in a series of
small steps.
Each of these small
steps is helped by its
own specific enzyme.
energy
energy
energy
energy
energy
At each step, a small
quantity of energy is
released.
energy
energy
energy
energy
energy
At one of these steps,
there is a need for
oxygen.
If oxygen is not
present, this step
cannot take place.
energy
energy
energy
This means that the
breakdown in the
absence of oxygen is
incomplete, and less
energy is released
than would be the
case with oxygen.
energy
energy
energy
This also means that
the products are
different in anaerobic
respiration.
The glucose is not
completely broken
down to carbon
dioxide and water.
The products in plant
tissue such as yeast
are alcohol and carbon
dioxide.
Anaerobic respiration in yeast.
This is where glucose is broken down in the _______ of
oxygen.
This is an __________ breakdown of glucose, so ____
energy is released.
It is ____ efficient than aerobic respiration.
The word equation for anaerobic respiration in yeast is –
Glucose -> ________ + carbon dioxide + energy
Word bank – heat, complete, energy, incomplete, alcohol,
more, less, oxygen, wine,
Anaerobic respiration.
This is where glucose is broken down in the absence of
oxygen.
This is an incomplete breakdown of glucose, so less energy
is released.
It is less efficient than aerobic respiration.
The word equation for anaerobic respiration in yeast is –
Glucose -> alcohol + carbon dioxide + energy
So what are we learning?
•Humans (and animals) have muscles which
can respire anaerobically too
•This does not mean that the whole
organism can respire anaerobically!
•The muscles work anaerobically when the
bloodstream cannot supply them with
oxygen as fast as it is being used up.
•This is a short term solution
•There are painful consequences!
So what are we learning?
•Just as in yeast, anaerobic respiration in
human muscles is an incomplete breakdown
of glucose, so less energy is released than
in aerobic respiration.
•The advantage is that it makes at least
some energy available in times of real
stress
•Glucose -> CO2 + lactic acid +energy
So what are we learning?
•Lactic acid is poisonous and causes cramp
as it builds up in the muscles
Take the Iron Man
challenge and learn
how lactic acid
feels!
Muscles break down the glucose to
release its energy by the process of
a______ respiration
Muscles need ___ in the form of glucose
and ______ to work
When you exercise the muscles, there is
an increase in oxygen intake (breathing
rate) and oxygen transport (heart rate).
aerobic
transport
oxygen
increase
food
intake
Muscles break down the glucose to release
its energy by the process of aerobic
respiration
Muscles need food in the form of glucose
and oxygen to work
When you exercise the muscles, there is
an increase in oxygen intake (breathing
rate) and oxygen transport (heart rate).
aerobic
transport
oxygen
increase
food
intake
The word equation for aerobic
respiration is +
->
This is
CO2
oxygen
+
+
breakdown of glucose
energy
complete
H20
glucose
aerobic
The word equation for aerobic
respiration is Glucose +oxygen -> CO2 + H20 +energy
This is complete breakdown of glucose
CO2
oxygen
energy
complete
H20
glucose
aerobic
The word equation for aerobic
respiration in yeast is -
+
This is
breakdown of glucose
CO2
energy
incomplete
oxygen
H20
glucose
anaerobic
alcohol
The word equation for aerobic
respiration in muscles is -
+ CO2
glucose
This is
CO2
breakdown of glucose
energy
lactic acid
incomplete anaerobic
glucose
H20
End of slide show.
Now away and respire quietly.