Williamwood High School
Biology Department
Biology National 4
Unit 1 – Cell Biology
Key area 7
Respiration
Name ______________________________
KA
1.7
Unit 1 – Cell Biology
Key area 7 – Respiration
Learning Objectives
1:7 Factors affecting respiration
I can…
1. state that respiration releases energy in cells.
2. name the type of energy stored in food.
3. state three reasons why cells require energy.
4. name the raw materials and products of respiration
5. describe the word equation for aerobic respiration in yeast, plant and
animal cells.
6. describe the word equation for anaerobic respiration in yeast and plants.
7. describe the word equation for anaerobic respiration in animal cells.
8. compare aerobic and anaerobic respiration in terms of oxygen use and
amount of energy released.
9. state the meaning of the word fermentation
10. describe the factors that can limit the rate of respiration in a cell.
Page 2
ENERGY FROM FOOD
•
Our body needs food to give us energy to keep our bodies functioning
properly.
State three things that this energy is used for.
___________________________
___________________________
___________________________
•
Food is also needed to keep us healthy.
Types of energy
• The type of energy stored in food is _______________ energy .
•
When food is burned, the chemical energy is changed into _________
energy.
•
The units used to measure the energy in food are called ___________.
Activity 1 Energy content of food
Different types of food have different energy content. We can compare
the energy content of different foods by looking carefully at the
‘Nutritional Information’ on the label. This gives lots of information,
including how much energy is in each 100g of the food (in kilojoules).
Page 3
•
•
•
•
•
Collect one food label.
Look at the ‘Nutritional Information’ and look for ‘Energy per 100g’.
Complete the table below.
Do the same for three more foods.
If you have time, choose one more food to do.
Type of food
•
•
Energy content of food
(kJ per 100g)
Draw a bar graph of your results.
If you are finished, you can use highlighters to colour the bars.
Hints for bar graph drawing
 Always use a pencil and ruler.
 Label both axes by copying the table headings exactly, including
the brackets. (Leave space to name the bars)
 Make an even scale from zero up to the highest number you need.
The scale must go up in even jumps, like 0, 20, 40, 60 etc.
 Space out your bars evenly. Make the bars equal widths.
 Use a ruler to draw the bars.
 Name each bar below it.
 There are no marks for shading or colouring in, and you could lose
marks if you go over the lines!
Page 4
ENERGY FROM FOOD
 We all need to get energy from our food every day.
 Some people need more energy in a day than others.
 How much energy a person needs depends on their age, size and activity.
Name three types of people who need to take in lots of energy every day.
_________________________
_________________________
_________________________
If you take in more energy in food than your body needs, you store this as fat
and your body weight ____________________.
If you take in less energy in food than your body needs, you use up your stored
fat and your body weight ____________________.
Activity 2 – 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 a special spoon to burn the food.
• You will burn three different types of food – carbohydrate, protein and
fat.
• The higher the temperature rise of the water, the more chemical
energy the food has.
A deflagrating
spoon
Page 5
Type of Food
Temperature Temperature Temperature Average
at start
at end (°C) change (°C) temperature
(°C)
change (°C)
Carbohydrate
Protein
Fat
Conclusion : The food which gave off the most heat when burned was the
____________________. The food which gave off the least amount of heat
was the ____________________.
The food which contained the most chemical energy at the start was the
______________________.
WHAT IS RESPIRATION?
•
The chemical process by which energy is released in cells is called
respiration.
1. What food source is the main source of energy for respiration?
____________________________________
2. Where does respiration happen?
____________________________________
3. When does respiration happen?
____________________________________
4. What controls the process?
_____________________________________
•
•
Respiration can be carried out either with oxygen or without oxygen.
First of all we will look at respiration with oxygen.
Page 6
Respiration with oxygen
Complete the diagram to show what substances enter a cell for respiration,
and what substances leave the cell.
ENERGY
PRODUCED
The raw materials for respiration are _________________ and
_____________________.
LOTS OF ENERGY IS PRODUCED FOR THE CELL TO USE.
The end products which are released from the cell are
______________ ____________ and _________________________.
WORD EQUATION FOR RESPIRATION WITH OXYGEN
________ + _______
Energy + Carbon Dioxide + ______
RAW MATERIALS
PRODUCTS
Page 7
CHECK TEST 1 – Circle the correct answer.
1. What type of energy is stored in food?
A
chemical
B
electrical
C
physical
D
mechanical
2. The unit of measurement for energy in food is
A
degrees
B
grams
C
kilometres
D
kilojoules
3. What kind of energy is released by burning food?
A
chemical and heat
B
heat and light
C
light and sound
D
sound and movement
4. Three groups measured the temperature rise when burning one gram of
sugar. Their results were:
Temperature rise (° C)
12
17
13
Group 1
Group 2
Group 3
The average temperature rise was
A
12° C
B
13° C
C
14° C
D
15° C
5. The raw materials used in respiration are
A
B
C
D
glucose and oxygen
glucose and water
carbon dioxide and water
carbon dioxide and oxygen
TOTAL
Page 8
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Limiting factors in respiration
 The rate of respiration in cells can vary. Sometimes it is fast, but at
other times it may be slow.
 How quickly our cells respire can be determined by several different
factors.
 These are called ________________ ________________.
 This is because they can limit (slow down) the rate of respiration.

________________ and _________________ are both needed for
respiration. If one of these is in short supply, respiration rate will
decrease or respiration may stop altogether.
The three main limiting factors for respiration are
_______________________________
_______________________________
_______________________________
If any one of these is in short supply, the respiration rate will
__________________________________________________.
Respiration Investigation

Your teacher will lead you through an investigation into the factors
affecting respiration. You will write this up formally on a separate sheet.
Page 9
Interpreting graphs for limiting factors
Complete the statements in the boxes to describe each graph.
Graph 1
As the glucose concentration
increases, the rate of respiration
______________________then
______________________.
Glucose concentration
Graph 2
As the oxygen concentration
increases, the rate of respiration
______________________then
______________________.
Oxygen concentration
Graph 3
As the ______________
increases, the rate of respiration
______________________ until
the temperature is 40°, then it
______________________.
Page 10
Respiration without oxygen in yeast and plants
•
•
•
•
•
Sometimes the conditions a plant is growing in means that there is very
little, or sometimes no oxygen available to the plant.
For example, if the soil is waterlogged then there is no oxygen available to
the roots of plants.
If yeast cells are growing in a liquid, they will run out of oxygen very
quickly.
The cells still must carry out respiration .
Cells are able to carry out respiration without oxygen, but it produces a
lot less energy.
Complete the diagram to show what substances enter a yeast cell for respiration
without oxygen, and what substances leave the cell.
A YEAST CELL
Very little ______________ is produced
Page 11
The only raw material for respiration without oxygen in yeast cells is
_________________
The end products which are released from the cell are
______________ ____________ and _________________________.
This process is also called _________________________.
WORD EQUATION FOR RESPIRATION WITHOUT OXYGEN IN YEAST
AND PLANT CELLS
______________
Energy
+ Carbon Dioxide + _________
RAW MATERIAL
PRODUCTS
Page 12
Respiration without oxygen in animal cells
•
•
•
Sometimes animal cells can have a low supply of oxygen.
For example, if a human is taking part in vigorous exercise their muscle
cells may not be able to get enough oxygen from the blood.
The cells still carry out respiration, but without oxygen.
Complete the diagram to show what substance enters an animal cell for
respiration without oxygen, and what substance builds up in the cell.
A HUMAN MUSCLE CELL
___________
________ builds
up
Very little ______________ is produced
The only raw material for respiration without oxygen in animal cells is
_________________
The end product which builds up in the cell is _____________________ .
This process is also called _________________________.
Page 13
WORD EQUATION FOR RESPIRATION WITHOUT OXYGEN IN ANIMAL
CELLS
______________
Energy
RAW MATERIAL
+
_________
PRODUCT
Build up of lactic acid in muscles
• If one set of muscles in the body are working really hard, they may not be
able to get enough oxygen, so lactic acid starts to build up.
•
The build up of lactic acid causes a burning pain in the muscles, and they
stop working properly.
•
This pain is called _____________ ________________ .
•
After the exercise stops, or after resting for a while, the lactic acid goes
away, and the muscles start working again.
Page 14
Check test 2
Circle the correct answer
1. The three main limiting factors in respiration are
A
B
C
D
light, carbon dioxide and water
oxygen, carbon dioxide and temperature
glucose, oxygen and water
glucose, oxygen and temperature
2. Which statement is correct?
A
B
C
D
Respiration with oxygen produces more energy than without oxygen
Respiration with oxygen produces less energy than without oxygen
Respiration with oxygen produces more glucose than without oxygen
Respiration with oxygen produces less glucose than without oxygen
3. The products of respiration without oxygen in yeast cells are
A
B
C
D
glucose and carbon dioxide
carbon dioxide and water
ethanol and carbon dioxide
ethanol and glucose
4. The products of respiration without oxygen in muscle cells is
A
B
C
D
lactic acid
water
carbon dioxide
oxygen
5. The other name for respiration without oxygen is
A
B
C
D
breathing
condensation
evaporation
fermentation
TOTAL
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