1. Gaseous exchange in animals and plants
7.5

2. Respiration Unbreathed air nitrogen (78%) oxygen (21%)
carbon dioxide (0.03%)

3. Respiration Breathed air nitrogen (78%) oxygen (21%)3
Respiration
Breathed air
nitrogen (78%)
oxygen (21%)
carbon dioxide (0.03%)

4. Respiration Unbreathed air Breathed air less oxygen4
Respiration
Unbreathed air
Breathed air
less oxygen
more carbon dioxide

5. support body activities
Respiration
energy
break down food
oxygen
support body activities
living cell

6. Respiration Word equation of respiration: food carbon dioxide + oxygen
+ water + energy

7. gaseous exchange (氣體交換)
Gaseous exchange in animals
oxygen in air
carbon dioxide in air
remove carbon dioxide from the body
taken in
gaseous exchange (氣體交換)

8. 7.15 Gaseous exchange in mealworms 1 wire gauze soda lime
Experiment video
Gaseous exchange in mealworms 1
wire gauze
soda lime
capillary tube
colour marker A
mealworm B

9. 7.15 a In what way is tube B different from tube A?
There is no mealworm in tube B. A B

10. 7.15 b What is the purpose of setting up tube B?
To eliminate the changes in the set-ups caused by changes in environmental factors, such as air
temperature and pressure. A B

11. 11
7.15 2
Measure this distance A B

12. Distance between the colour marker
7.15 2
Tube
Distance between the colour marker
and the stopper (cm)
At the beginning
20 minutes later A B

13. 7.15
Discussion
1 Which tube contains less gas at the end of the experiment?
Tube A.

14. 7.15 2 Try to explain the result in tube A.14
7.15
2 Try to explain the result in tube A.
The mealworms take in ________
and give out ______________. The ______________ is absorbed by soda lime.
oxygen
carbon dioxide
carbon dioxide

15. is pushed towards the boiling tube.
7.15
The gas pressure inside tube A therefore ___________ and becomes ___________ than the atmospheric pressure.
decreases
lower
As a result, the colour marker _____________________________
is pushed towards the boiling tube.

16. 7.15
3 We should not hold the boiling tubes with our hands during the experiment. Why?
The heat energy from our hands will heat up the air inside the tubes and cause the air to expand. This
affects the experimental results.

17. The human respiratory system
Humans and most animals have a respiratory system (呼吸系統) for gaseous exchange.

18. 7.16 Major parts of our respiratory system
3D model
Major parts of our respiratory system
Identify the major parts of the respiratory system.
Label the diagram.

19. 19
7.16
nasal cavity
trachea
bronchus
bronchiole

20. 20
7.16
air sac
rib
intercostal muscle
lung
diaphragm

21. The human respiratory system
air
nostrils
nasal cavity
trachea

22. The human respiratory system22
The human respiratory system
air
bronchi
bronchioles
air sacs

23. lungs are protected by the rib cage (肋骨籃)23
The human respiratory system
lungs are protected by the rib cage (肋骨籃)

24. The human respiratory system24
The human respiratory system
backbone
chest bone
rib

25. The human respiratory system25
The human respiratory system
intercostal muscles
diaphragm

26. Gaseous exchange in the air sac
3D animation

27. Gaseous exchange in the air sac27
Gaseous exchange in the air sac
carbon dioxide
oxygen
direction of blood flow
air sac
capillary

28. The breathing mechanism
Do you know how breathing is brought about?

29. 7.4 Feeling your breath Take a deep breath.
Feel the movement of your ribs.

30. 7.4 a Which way do your ribs move when you breathe in?30
7.4
a Which way do your ribs move when you breathe in?
They move upwards and outwards.

31. 7.4 b Which way do your ribs move when you breathe out?31
7.4
b Which way do your ribs move when you breathe out?
They move downwards and inwards.

32. The breathing mechanism32
The breathing mechanism
Movements are brought by the actions of …
intercostal muscles
diaphragm

33. 33
a Breathing in
rib
lung
intercostal muscles
diaphragm

34. a Breathing in 1a Intercostal muscles contract.34
a Breathing in
1a Intercostal muscles contract.
Ribs move upwards and outwards.
1b Diaphragm flattens.

35. a Breathing in Gas pressure inside it decreases.35
a Breathing in
Gas pressure inside it decreases.
2 Volume of chest cavity increases.

36. 36
a Breathing in
3 Air is drawn in.

37. b Breathing out 1a Intercostal muscles relax.37
b Breathing out
1a Intercostal muscles relax.
Ribs move downwards and inwards.

38. 38
b Breathing out
1b Diaphragm returns to dome shape.

39. b Breathing out 2 Volume of chest cavity decreases.39
b Breathing out
2 Volume of chest cavity decreases.
Gas pressure inside it increases.

40. 40
b Breathing out
3 Air is forced out.

41. 7.17
Animation
Using a model to show the action of the intercostal muscles during breathing B 1 A
rubber band
rib cage model (肋骨籃模型) C B

42. 7.17 1 Each part represents… ribs intercostal muscles chest bone42
7.17 1
Each part represents…
ribs B A
intercostal muscles C B
chest bone
backbone

43. 43
7.17 2
Position X H G
measure this length D F E I

44. 44
7.17 3
Position Y N J M
measure this length K L O

45. 7.17 4 Which rubber band, HI or NO, is shorter in length? NO. N H O I45
7.17
4 Which rubber band, HI or NO, is shorter in length?
NO. N H O I

46. 46
7.17
5 In which case, position X or Y, are the intercostal muscles contracting?
Position X
Position Y

47. 7.17 6 Which parallelogram, DEFG or JKLM, is larger in area? G J M D F47
7.17
6 Which parallelogram, DEFG or JKLM, is larger in area? G J M D F K L E

48. 7.17 7 In which case, position X or Y, is the chest volume greater?48
7.17
7 In which case, position X or Y, is the chest volume greater?
Position X
Position Y

49. 49
7.17
8 When the model is set from position X to position Y, the rubber band becomes ___________. This represents the intercostal muscles are ___________.
shortened
contracting

50. 50
7.17
The ribs, move __________ and the chest volume __________. This is similar to the situation when we are breathing __________.
upwards
increases in

51. balloon-bell jar model
7.18
Animation
Using a model to show the action of the diaphragm during breathing 1
glass tube
balloon-bell jar model
(氣球及鐘形罩模型)
Y-piece
balloons
rubber sheet

52. 52
7.18
Each part represents… 1
trachea
bronchi
lungs
diaphragm

53. 7.18 2

54. 54
7.18 2

55. 7.18
3 What happens to the balloons when the rubber sheet is pulled down?
The balloons become _______.
bigger

56. 56
7.18
When the rubber sheet is pulled down, the volume of the bell jar __________ and the gas pressure inside the bell jar becomes __________. 3
increases
lower

57. 57
7.18 3
Therefore air flows ________ the balloons. This is similar to the situation when we are breathing ________.
into in

58. 7.18
4 What happens to the balloons when the rubber sheet is pushed up?
The balloons become ________.
smaller

59. 59
7.18 4
When the rubber sheet is pushed up, _____________________________ _______________________________________________________________________________________
the volume of the bell jar decreases and the gas pressure inside the bell jar becomes higher. Therefore air flows out of the balloons.

60. 7.18 4 This is similar to the situation when we are _____________.60
7.18 4
This is similar to the situation when we are _____________.
breathing out

61. Gaseous exchange in animals
In humans, gaseous exchange takes place in the ________.
air sacs

62. Gaseous exchange in animals62
Gaseous exchange in animals
In humans, breathing is brought about by the actions of the
_________________ between the ribs, and the ___________ that is located below the rib cage.
intercostal muscles
diaphragm

63. 5 1 When we breathe in, the intercostal muscles _________. contract
The ribs move _________ and __________.
upwards
outwards
At the same time, the diaphragm becomes _________.
flattened

64. 64 5
These movements cause the volume of the chest cavity to _________ and therefore the gas pressure inside it ___________. Air is then drawn into the lungs. 1
increase
decreases

65. diaphragm is dome-shaped5
Well done!
2 Which photo, A or B, was taken when the man was breathing out? Why? A B
rib
lung
diaphragm is dome-shaped
heart
diaphragm

66. Gaseous exchange in plants
Photosynthesis
Green plants
give out
oxygen
carbon dioxide
take in

67. Gaseous exchange in plants67
Gaseous exchange in plants
Respiration
Green plants
give out
take in
oxygen
carbon dioxide
give out
take in

68. Gaseous exchange in plants68
Gaseous exchange in plants
In a day…
Green plants
oxygen and carbon dioxide:
uptake or release?

69. Gaseous exchange in plants69
Gaseous exchange in plants
Depends on the rates of photosynthesis and respiration
Green plants

70. 7.19 When do green plants take in and give out carbon dioxide?70
7.19
Experiment video
When do green plants take in and give out carbon dioxide?
hydrogencarbonate indicator

71. 7.19 Concentration of carbon dioxide > 0.03% ~ 0.03%
(normal level in air)
< 0.03%
Colour of
hydrogen-carbonate
indicator
Yellow
Red
Purple

72. 7.19 1 green leaves aluminium foil
each tube contains 3 cm3 of hydrogencarbonate indicator A B C D

73. 7.19 a What is the purpose of setting up tube B?73
7.19
a What is the purpose of setting up tube B?
To make sure that the result in tube A is caused by the presence of the green leaf. A B C D

74. 7.19 b What is the purpose of setting up tube D?74
7.19
b What is the purpose of setting up tube D?
To make sure that the result in tube C is caused by the presence of the green leaf. A B C D

75. 75
7.19 2
leave for one hour A B C D

76. 76
7.19 2
represent in the daytime
represent at night A B C D

77. hydrogencarbonate indicator
7.19 3
Tube
Colour of the
hydrogencarbonate indicator
At the beginning
After one hour A
Red B C D
Purple
Red
Yellow
Red

78. 7.19
4a Compare the results in tube A and tube B. What does the difference show?
Tube A
Tube B

79. 79
7.19
4a Compare the results in tube A and tube B. What does the difference show?
The green leaf takes in carbon dioxide from the air in the presence of light.
Tube A
Tube B

80. 7.19
b Compare the results in tube C and tube D. What does the difference show?
Tube C
Tube D

81. 81
7.19
b Compare the results in tube C and tube D. What does the difference show?
The green leaf gives out carbon dioxide in the dark.
Tube C
Tube D

82. rate of photosynthesis82
Gaseous exchange in plants
In the daytime
rate of photosynthesis
net release of oxygen
higher than
rate of respiration
net uptake of carbon dioxide

83. Gaseous exchange in plants83
Gaseous exchange in plants
At night
photosynthesis stops
net release of carbon dioxide
respiration continues
net uptake of oxygen

84. Gaseous exchange in plants
In the daytime, there is a net release of oxygen and a net
uptake of carbon dioxide in green plants.

85. Gaseous exchange in plants85
Gaseous exchange in plants
At night, green plants take in oxygen and give out carbon dioxide.

86. The balance of oxygen and carbon dioxide in nature86
The balance of oxygen and carbon dioxide in nature
oxygen in air
releases oxygen
taken up during
respiration of
animals and plants
photosynthesis of green plants
releases carbon dioxide
taken up during
carbon dioxide in air

87. The balance of oxygen and carbon dioxide in nature
Living things carry out respiration. Green plants carry out photosynthesis.

88. The balance of oxygen and carbon dioxide in nature88
The balance of oxygen and carbon dioxide in nature
The two processes help keep a balance of oxygen and carbon dioxide in nature.

89. 89
The effect of the increasing amount of carbon dioxide in the atmosphere on us
Animation
Sun
atmosphere
Earth

90. The greenhouse effect
1 Sunlight passes through the atmosphere and reaches the Earth. 1

91. 2 Heat energy is reflected back from the Earth’s surface.91
The greenhouse effect
2 Heat energy is reflected back from the Earth’s surface. 2

92. 3a Some heat energy is lost to space.92
The greenhouse effect
3a Some heat energy is lost to space. 3a

93. The greenhouse effect 3b93
The greenhouse effect
3b Some heat energy is absorbed by some gases in the atmosphere, leading to greenhouse effect. 3b

94. The effect of the increasing amount of carbon dioxide in the atmosphere on us
The burning of fossil fuels releases a lot of carbon dioxide.

95. The effect of the increasing amount of carbon dioxide in the atmosphere on us
large areas of forests are cleared
amount of carbon dioxide absorbed during photosynthesis drops

96. amount of carbon dioxide in the atmosphere increases

97. amount of carbon dioxide in the atmosphere increases97
amount of carbon dioxide in the atmosphere increases
traps more heat and enhances greenhouse effect
average temperatures of the Earth keep increasing

98. 98
amount of carbon dioxide in the atmosphere increases
global warming (全球增温)
traps more heat and enhances greenhouse effect
average temperatures of the Earth keep increasing

99. Global warming
speeds up the melting of ice at polar regions

100. speeds up the melting of ice at polar regions
100
Global warming
speeds up the melting of ice at polar regions
living things at polar regions may lose their habitats

101. speeds up the melting of ice at polar regions
101
Global warming
speeds up the melting of ice at polar regions
sea level rises
flooding of low-lying areas

102. causes climate changes
102
Global warming
causes climate changes
more frequent droughts and storms

103. The effect of the increasing amount of carbon dioxide in the atmosphere on us
The increasing amount of carbon dioxide in the atmosphere enhances the greenhouse effect.

104. 104
The effect of the increasing amount of carbon dioxide in the atmosphere on us
The global temperatures continue to rise. This is known as global warming.

105. 6 1 Which of the following leads to global warming?
A The atmospheric temperature rises continuously.
B The amount of oxygen in the atmosphere decreases.
C The amount of carbon dioxide in the atmosphere decreases.
D The amount of carbon dioxide in the atmosphere increases.

106. 6
2 Which of the following is not likely to be caused by global warming?
A An increase in the amount of oxygen in the atmosphere
B Melting of ice caps
Excellent!
C Climate change
D Flooding of low-lying areas