Key area 7
Respiration
Energy In Our Food
Learning Intention:
To know the importance of food.
Success Criteria:
Be able to state the type of energy stored in
food.
Be able to describe how we measure the
energy content in food.
Why do we need food?
• Our body needs food to give us energy for
movement, heat production and growth.
• Food is also needed to keep us healthy.
• The type of energy stored in food is chemical
energy .
• When food is burned, the chemical energy is
changed into heat energy.
• The units used to measure the energy in food
are called kilojoules.
Why do we need food?
Video Link
Activity 1
• Collect one food label.
• Look at the ‘Nutritional Information’
and look for ‘Energy per 100g’.
• Complete the table on the next slide.
• Do the same for three more foods.
• If you have time, choose one more food
to do.
• Draw a bar graph of your results.
Energy content of food
Type of food
Energy content of
food (kJ per 100g)
Energy in food
• The energy we get from our food allows
us to carry out everyday functions.
• Some people need more energy than
others.
Think about energy
Answer the following questions:
1. What might affect the amount of
energy a person needs in a day?
2. What would happen to your body if you
took in more energy from your food
than you need?
3. What would happen to your body if you
didn’t get enough energy from your
food to carry out your daily functions?
Energy in food
• We can measure the energy
in food by measuring the heat
it produces when it is burned.
• Your teacher will show you
how to use this special spoon
to burn the food.
• You will test three different
types of food –
carbohydrate, protein and
fat.
Deflagrating spoon
Activity 2 - Burning food
• Here is the method you will use. Listen carefully to
your teacher’s instructions.
• Wear safety goggles! Do not play with fire!
thermometer
boiling tube
with 40ml cold
water
Deflagrating spoon
Clamp stand
One level spoonful
of burning food
Set fire to food in a
bunsen burner, then
quickly place spoon
under boiling tube. Hold
steady until the flame
goes out.
Activity 2
Type of Food Temperature
at start (°C)
Temperature Temperature
at end (°C)
change (°C)
Carbohydrate
Protein
Fat
• Now carry out the experiment and record
your results.
• Complete the conclusion for your experiment.
Respiration
Learning Intention:
Know what respiration is and why we need it.
Success Criteria:
Be able to describe the process of respiration.
Be able to state the summary equation for
respiration with oxygen.
Be able to distinguish between the raw materials
and products of respiration with oxygen.
Starter Activity:
Answer the following questions
1. Why do we need food?
2. What type of energy is stored in food?
3. What type of energy is this converted to when
food is burned?
4. What units are used to measure the energy in
food?
What is respiration?
• The chemical process by which energy is
released in cells is called respiration.
• It happens in all living cells, all of the
time.
• The main food source of energy for
respiration in cells is glucose .
• This process is controlled by enzymes.
• Respiration can be carried out either
with oxygen or without oxygen.
Watch and Listen
• Video Clip
Who needs respiration?
• Every living cell needs to carry out
respiration.
• This includes plants, animals, bacteria
and yeast.
• Cells can carry out respiration with or
without oxygen.
• First we will look at respiration WITH
oxygen.
Respiration with oxygen
A human cell
Carbon dioxide
Glucose
water
Oxygen
ENERGY is produced for heat,
movement etc.
Human cells get their glucose and oxygen from the blood.
They also release the carbon dioxide and water back into the
blood.
Respiration with oxygen
• The raw materials are glucose and
oxygen.
• Glucose contains a store of energy.
• Glucose is broken down with the help of
oxygen.
• The end products are carbon dioxide
and water. These are released from the
cell.
• This process produces lots of energy!
Respiration with oxygen
• The following word equation summarises
respiration with oxygen in cells:
Glucose + Oxygen
Raw Materials
Energy + Carbon Dioxide + Water
Products
Rate of Respiration
Learning Intention:
Know how the rate of respiration is affected.
Success Criteria:
Be able to name the three limiting factors that
affect the rate of respiration.
Be able to describe the effect a limiting factor has
on the rate of respiration.
Carry out an investigation into one of these limiting
factors.
Rate of Respiration
• How quickly our cells respire can be
determined by several different
factors.
• These are called limiting factors.
• This is because they can limit (slow
down) the rate of respiration.
Limiting factors in respiration
A human cell
Carbon dioxide
Glucose
water
Oxygen
ENERGY is produced for heat,
movement etc.
Glucose and oxygen are both needed for respiration. If one
of these is in short supply, respiration rate will decrease or
respiration may stop altogether.
Limiting Factors
• Oxygen concentration can limit the rate
of respiration.
• Glucose concentration can limit the rate
of respiration.
• Temperature can also limit the rate of
respiration. This is because respiration
is controlled by enzymes, and
temperature affects how fast the
enzymes work.
Limiting
factors
• As the glucose
concentration
increases, the
respiration rate
increases.
• As the oxygen
concentration
increases, the
respiration rate also
increases.
• Low glucose or
oxygen
concentration would
result in low
respiration rate.
Glucose concentration
Oxygen concentration
Temperature and respiration rate
• A low temperature - 10°C for example –
would result in a low rate of respiration.
Starter
On a show me board, write down three
limiting factors that affect the rate of
respiration.
Respiration Investigation
Learning Intention:
Carrying out a investigation to find out the affect
of limiting factors on germinating seeds.
Success Criteria:
Be able to write up an aim and method of how to
carry out an investigation.
Be able to carry out the investigation in a safe and
responsible manner.
Respiration Investigation
• You will carry out an
investigation on the
effects of limiting
factors on germinating
(starting to grow) seeds.
• In order to germinate,
seeds need energy from
respiration.
• If any requirements for
respiration are in short
supply, the seeds will not
be able to germinate
properly.
Discussion
• You will investigate how your chosen
factor affects the germination of
seeds.
• Your teacher will lead a class discussion
to find out all of your ideas on how to
carry out this investigation.
• You will discuss the apparatus you will
use and the safety precautions you will
take.
Writing Up an Investigation
You will complete an investigation report
which will include the following sections:
• Aim
• Hypothesis
• Diagram of apparatus
• Method
• Results table
• Conclusion
Respiration investigation flipchart
Results table
Number of seeds Number of seeds
planted
germinated
Respiration Investigation
Learning Intention:
Carrying out a investigation to find out the affect
of limiting factors on germinating peas.
Success Criteria:
Be able to write up an aim and method of how to
carry out an investigation.
Be able to carry out the investigation in a safe and
responsible manner.
Appropriate
Clip art to
topic
Respiration Without
Oxygen
Learning Intention:
To state the two pathways of respiration without
oxygen.
Success Criteria:
Be able to describe the conditions that animals,
plants and yeast would be in to carry out
respiration without oxygen.
Be able to write summary equations for respiration
without oxygen in plant and yeast cells and in
animal cells.
Watch and Listen
• Video Clip
Respiration Without Oxygen
• Sometimes the conditions a plant is
growing in means that there is very
little, or sometimes no oxygen available
to the plant.
• They still must carry out respiration .
Respiration without oxygen
A yeast cell
Carbon dioxide
Glucose
Alcohol
A little ENERGY is produced
Yeast cells get their glucose from their surroundings. They
also release the carbon dioxide and alcohol back into the
surroundings.
Respiration without oxygen
• In yeast and plant cells, the raw
material is glucose.
• The products are carbon dioxide and
alcohol.
• This process produces only a little
energy.
• Respiration without oxygen in plants is
called fermentation.
Respiration without oxygen
• The following equation summarises
respiration without oxygen in yeast and
plant cells:
Glucose
Raw Material
Carbon Dioxide + Alcohol +
Products
A little energy
Respiration Without Oxygen
• Sometimes animal cells can have a low
supply of oxygen, for example if a
human is taking part in vigorous
exercise.
• The cells still carry out respiration.
Respiration without oxygen
A human cell
Lactic acid
Glucose
A little ENERGY is produced
Muscle cells sometimes have to respire without oxygen. This
causes lactic acid to build up inside the muscle cells.
Your teacher will show you how to demonstrate this.
Respiration without oxygen
• Respiration without oxygen in animal
cells uses glucose as the raw material.
• The product is lactic acid.
• There is very little energy produced in
this process.
• Respiration without oxygen in animals is
also called fermentation.
Respiration without oxygen
• The following equation summarises
respiration without oxygen in animal
cells:
Glucose
Lactic Acid +
Raw Material
Products
A little energy
Appropriate
Clip art to
topic
Respiration Without
Oxygen
Learning Intention:
To state the two pathways of respiration without
oxygen.
Success Criteria:
Be able to describe the conditions that animals,
plants and yeast would be in to carry out
respiration without oxygen.
Be able to write summary equations for respiration
without oxygen in plant and yeast cells and in
animal cells.