7.5 Gaseous exchange in animals and plants
7.5 Gaseous exchange
in animals and
plants
1
7.5 Gaseous exchange in animals and plants
Respiration
Unbreathed air
nitrogen (78%)
oxygen
(21%)
carbon dioxide
(0.03%)
2
7.5 Gaseous exchange in animals and plants
Respiration
Breathed air
oxygen (21%)
carbon dioxide
(0.03%)
nitrogen (78%)
3
7.5 Gaseous exchange in animals and plants
Respiration
Unbreathed air
Breathed air
less oxygen
more carbon dioxide
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7.5 Gaseous exchange in animals and plants
Respiration
break down
food
energy
oxygen
living cell
support body
activities
7.5 Gaseous exchange in animals and plants
Respiration
Word equation of respiration:
food
+ oxygen
carbon dioxide
+ water + energy
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7.5 Gaseous exchange in animals and plants
Gaseous exchange in animals
carbon dioxide in air
remove
carbon dioxide
from the body
oxygen in air
taken in
gaseous exchange (氣體交換)
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7.5 Gaseous exchange in animals and plants
7.15
Experiment
video
Gaseous exchange in mealworms
1 wire
soda
capillary colour
gauze lime
tube
marker
A
mealworm
B
7.5 Gaseous exchange in animals and plants
7.15
a In what way is tube B different from
tube A?
There is no mealworm in tube B.
A
B
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7.5 Gaseous exchange in animals and plants
7.15
b What is the purpose of setting up
tube B?
To eliminate the changes in the
set-ups caused by changes in
Aenvironmental factors, such as air
temperature and pressure.
B
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7.5 Gaseous exchange in animals and plants
7.15
2
Measure this distance
A
B
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7.5 Gaseous exchange in animals and plants
7.15
2
Tube
A
B
Distance between the colour marker
and the stopper (cm)
At the beginning
20 minutes later
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7.5 Gaseous exchange in animals and plants
7.15
Discussion
1 Which tube contains less gas at
the end of the experiment?
Tube A.
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7.5 Gaseous exchange in animals and plants
7.15
2 Try to explain the result in tube A.
The mealworms take in ________
oxygen
and give out ______________.
carbon dioxide
The ______________
carbon dioxide is absorbed
by soda lime.
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7.5 Gaseous exchange in animals and plants
15
7.15
The gas pressure inside tube A
decreases and
therefore ___________
lower
becomes ___________
than the
atmospheric pressure.
As a result, the colour marker
_____________________________
is pushed towards the boiling
tube.
7.5 Gaseous exchange in animals and plants
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.
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7.5 Gaseous exchange in animals and plants
The human respiratory system
Humans and most
animals have a
respiratory system
(呼吸系統) for
gaseous exchange.
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7.5 Gaseous exchange in animals and plants
7.16
Major parts of our respiratory
system
Identify the major parts of the
respiratory system.
Label the diagram.
3D model
7.5 Gaseous exchange in animals and plants
7.16
nasal cavity
trachea
bronchus
bronchiole
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7.5 Gaseous exchange in animals and plants
7.16
air sac
rib
intercostal
muscle
lung
diaphragm
7.5 Gaseous exchange in animals and plants
21
The human respiratory system
air
nostrils
nasal cavity
trachea
7.5 Gaseous exchange in animals and plants
22
The human respiratory system
air
bronchi
bronchioles
air sacs
7.5 Gaseous exchange in animals and plants
The human respiratory system
lungs are protected by the
rib cage (肋骨籃)
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7.5 Gaseous exchange in animals and plants
The human respiratory system
backbone
rib
chest bone
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7.5 Gaseous exchange in animals and plants
The human respiratory system
diaphragm
intercostal
muscles
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7.5 Gaseous exchange in animals and plants
Gaseous exchange in the air sac
3D animation
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7.5 Gaseous exchange in animals and plants
Gaseous exchange in the air sac
oxygen
direction of
blood flow
carbon
dioxide
air sac
capillary
7.5 Gaseous exchange in animals and plants
The breathing mechanism
Do you know
how breathing is
brought about?
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7.5 Gaseous exchange in animals and plants
7.4
Feeling your breath
Take a deep breath.
Feel the movement of
your ribs.
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7.5 Gaseous exchange in animals and plants
7.4
a Which way do your ribs move when
you breathe in?
They move upwards
and outwards.
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7.5 Gaseous exchange in animals and plants
7.4
b Which way do your ribs move when
you breathe out?
They move downwards
and inwards.
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7.5 Gaseous exchange in animals and plants
The breathing mechanism
Movements are brought by the
actions of …
intercostal
muscles
diaphragm
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7.5 Gaseous exchange in animals and plants
a
Breathing in
rib
intercostal
muscles
diaphragm
lung
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7.5 Gaseous exchange in animals and plants
a
Breathing in
1a Intercostal muscles contract.
Ribs move
upwards and
outwards.
1b Diaphragm
flattens.
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7.5 Gaseous exchange in animals and plants
a
Breathing in
Gas pressure
inside it
decreases.
2 Volume of
chest cavity
increases.
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7.5 Gaseous exchange in animals and plants
a
Breathing in
3 Air is drawn in.
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7.5 Gaseous exchange in animals and plants
b
Breathing out
1a Intercostal muscles relax.
Ribs move
downwards
and inwards.
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7.5 Gaseous exchange in animals and plants
b
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Breathing out
1b Diaphragm
returns to
dome shape.
7.5 Gaseous exchange in animals and plants
b
39
Breathing out
2 Volume of
chest cavity
decreases.
Gas pressure
inside it
increases.
7.5 Gaseous exchange in animals and plants
b
Breathing out
3 Air is forced
out.
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7.5 Gaseous exchange in animals and plants
7.17
Animation
Using a model to show the action of
the intercostal muscles during
breathing
B
A
1
rib cage model
rubber band
C
B
(肋骨籃模型)
7.5 Gaseous exchange in animals and plants
7.17
1 Each part represents…
ribs
B
C
chest bone
B
A
intercostal
muscles
backbone
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7.5 Gaseous exchange in animals and plants
7.17
2
Position X
H
measure
this
length
F
D
E
G
I
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7.5 Gaseous exchange in animals and plants
7.17
3
Position Y
N
J
M
L
K
O
measure
this length
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7.5 Gaseous exchange in animals and plants
7.17
4 Which rubber band, HI or NO, is
shorter in length?
NO.
N
H
O
I
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7.5 Gaseous exchange in animals and plants
46
7.17
5 In which case, position X or Y, are
the intercostal muscles contracting?
Position Y
Position X
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7.5 Gaseous exchange in animals and plants
7.17
6 Which parallelogram, DEFG or
JKLM, is larger in area?
G
J
M
F
K
L
D
E
7.5 Gaseous exchange in animals and plants
48
7.17
7 In which case, position X or Y, is the
chest volume greater?
Position X
Position Y
7.5 Gaseous exchange in animals and plants
7.17
8 When the model is set from
position X to position Y, the rubber
shortened This
band becomes ___________.
represents the intercostal muscles
contracting
are ___________.
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7.5 Gaseous exchange in animals and plants
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7.17
upwards and the
The ribs, move __________
increases This is
chest volume __________.
similar to the situation when we are
breathing __________.
in
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7.5 Gaseous exchange in animals and plants
7.18
Animation
Using a model to show the action of
the diaphragm during breathing
1 glass tube
balloon-bell
Y-piece
jar model
balloons
(氣球及鐘形罩模型)
rubber sheet
7.5 Gaseous exchange in animals and plants
7.18
1 Each part represents…
trachea
bronchi
lungs
diaphragm
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7.5 Gaseous exchange in animals and plants
7.18
2
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7.5 Gaseous exchange in animals and plants
7.18
2
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7.5 Gaseous exchange in animals and plants
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7.18
3 What happens to the balloons when
the rubber sheet is pulled down?
bigger
The balloons become _______.
7.5 Gaseous exchange in animals and plants
7.18
3 When the rubber sheet is pulled
down, the volume of the bell jar
increases and the gas pressure
__________
inside the bell jar becomes
lower
__________.
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7.5 Gaseous exchange in animals and plants
7.18
3 Therefore air flows ________
the
into
balloons. This is similar to the
situation when we are breathing
in
________.
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7.5 Gaseous exchange in animals and plants
58
7.18
4 What happens to the balloons when
the rubber sheet is pushed up?
smaller
The balloons become ________.
7.5 Gaseous exchange in animals and plants
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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.
_____________________________
7.5 Gaseous exchange in animals and plants
7.18
4 This is similar to the situation when
breathing out
we are _____________.
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7.5 Gaseous exchange in animals and plants
Gaseous exchange in animals
In humans, gaseous exchange
air sacs
takes place in the ________.
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7.5 Gaseous exchange in animals and plants
Gaseous exchange in animals
In humans, breathing is brought
about by the actions of the
intercostal muscles between the
_________________
ribs, and the ___________
diaphragm that is
located below the rib cage.
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7.5 Gaseous exchange in animals and plants
5
1 When we breathe in, the intercostal
contract
muscles _________.
The ribs move _________
upwards and
__________.
outwards
At the same time, the diaphragm
becomes _________.
flattened
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7.5 Gaseous exchange in animals and plants
5
1 These movements cause the
volume of the chest cavity to
increase and therefore the gas
_________
decreases
pressure inside it ___________.
Air is then drawn into the lungs.
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7.5 Gaseous exchange in animals and plants
5
2 Which photo, A or B, was taken
when the man was breathing out?
Why?
A
rib
lung
heart
diaphragm
B
diaphragm
is domeshaped
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7.5 Gaseous exchange in animals and plants
Gaseous exchange in plants
Photosynthesis
Green plants
give out
oxygen
carbon dioxide
take in
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7.5 Gaseous exchange in animals and plants
Gaseous exchange in plants
Respiration
Green plants
give
takeout
in
oxygen
carbon dioxide
give
take out
in
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7.5 Gaseous exchange in animals and plants
Gaseous exchange in plants
In a day…
Green plants
oxygen and carbon dioxide:
uptake or release?
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7.5 Gaseous exchange in animals and plants
Gaseous exchange in plants
Depends on the rates
of photosynthesis
and respiration
Green plants
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7.5 Gaseous exchange in animals and plants
7.19
Experiment
video
When do green plants take in and
give out carbon dioxide?
hydrogencarbonate
indicator
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7.5 Gaseous exchange in animals and plants
7.19
Concentration
of
carbon dioxide
Colour of
hydrogencarbonate
indicator
> 0.03%
~ 0.03%
(normal
level in air)
< 0.03%
Yellow
Red
Purple
7.5 Gaseous exchange in animals and plants
72
7.19
1
green leaves
aluminium foil
A
B
C
D
each tube contains
3 cm3 of
hydrogencarbonate
indicator
7.5 Gaseous exchange in animals and plants
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
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7.5 Gaseous exchange in animals and plants
7.19
b What is the purpose of setting up
tube D?
A
B
C
To make sure that
the result in tube
C is caused by the
presence of the
green
leaf.
D
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7.5 Gaseous exchange in animals and plants
7.19
2
leave for one hour
A
B
C
D
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7.5 Gaseous exchange in animals and plants
7.19
2 represent in
the daytime
A
B
C
represent
at night
D
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7.5 Gaseous exchange in animals and plants
7.19
3
Tube
A
B
C
D
Colour of the
hydrogencarbonate indicator
At the beginning
After one hour
Red
Red
Red
Red
Purple
Red
Yellow
Red
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7.5 Gaseous exchange in animals and plants
7.19
4a Compare the results in tube A and
tube B. What does the difference
show?
Tube A
Tube B
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7.5 Gaseous exchange in animals and plants
7.19
4a Compare the results in tube A and
tube B. What does the difference
show?
The
green
Tube
A leaf takes
Tube in
B carbon
dioxide from the air in the
presence of light.
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7.5 Gaseous exchange in animals and plants
7.19
b Compare the results in tube C and
tube D. What does the difference
show?
Tube C
Tube D
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7.5 Gaseous exchange in animals and plants
7.19
b Compare the results in tube C and
tube D. What does the difference
show?
TheTube
greenCleaf gives
out
Tube
D carbon
dioxide in the dark.
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7.5 Gaseous exchange in animals and plants
Gaseous exchange in plants
In the daytime
net release
of oxygen
net uptake of
carbon dioxide
rate of
photosynthesis
higher
than
rate of
respiration
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7.5 Gaseous exchange in animals and plants
Gaseous exchange in plants
At night
photosynthesis
stops
respiration
continues
net release of
carbon dioxide
net uptake
of oxygen
7.5 Gaseous exchange in animals and plants
Gaseous exchange in plants
In the daytime, there is a net
release of oxygen and a net
uptake of carbon dioxide in green
plants.
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7.5 Gaseous exchange in animals and plants
Gaseous exchange in plants
At night, green plants take in
oxygen and give out carbon
dioxide.
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7.5 Gaseous exchange in animals and plants
86
The balance of oxygen and
carbon dioxide in nature
oxygen in air
photosynthesis
of green plants
releases
oxygen
taken up
during
taken up
during respiration of
animals and
releases plants
carbon
dioxide
carbon dioxide in air
7.5 Gaseous exchange in animals and plants
The balance of oxygen and
carbon dioxide in nature
Living things carry out
respiration.
Green plants carry out
photosynthesis.
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7.5 Gaseous exchange in animals and plants
The balance of oxygen and
carbon dioxide in nature
The two processes help keep a
balance of oxygen and carbon
dioxide in nature.
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7.5 Gaseous exchange in animals and plants
The effect of the increasing
amount of carbon dioxide in the
atmosphere on us
Animation
Sun
atmosphere
Earth
7.5 Gaseous exchange in animals and plants
The greenhouse effect
1 Sunlight passes through the
atmosphere and reaches the Earth.
1
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7.5 Gaseous exchange in animals and plants
The greenhouse effect
2 Heat energy is reflected back from
the Earth’s surface.
2
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7.5 Gaseous exchange in animals and plants
The greenhouse effect
3a Some heat energy is lost to space.
3a
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7.5 Gaseous exchange in animals and plants
The greenhouse effect
3b Some heat energy is absorbed by
some gases in the atmosphere,
leading to greenhouse effect.
3b
7.5 Gaseous exchange in animals and plants
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.
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7.5 Gaseous exchange in animals and plants
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
7.5 Gaseous exchange in animals and plants
amount of carbon dioxide in
the atmosphere increases
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7.5 Gaseous exchange in animals and plants
amount of carbon dioxide in
the atmosphere increases
traps more heat and
enhances greenhouse effect
average temperatures of the
Earth keep increasing
97
7.5 Gaseous exchange in animals and plants
amount of carbon dioxide in
the atmosphere increases
traps more heat and
global
warming
(全球增温)
enhances greenhouse effect
average temperatures of the
Earth keep increasing
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7.5 Gaseous exchange in animals and plants
Global warming
speeds up the
melting of ice at
polar regions
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7.5 Gaseous exchange in animals and plants
Global warming
speeds up the
melting of ice at
polar regions
living things at
polar regions
may lose their
habitats
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7.5 Gaseous exchange in animals and plants
Global warming
speeds up the
melting of ice at
polar regions
sea level rises
flooding of lowlying areas
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7.5 Gaseous exchange in animals and plants
Global warming
causes climate
changes
more frequent
droughts and
storms
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7.5 Gaseous exchange in animals and plants
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.
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7.5 Gaseous exchange in animals and plants
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.
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7.5 Gaseous exchange in animals and plants
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.
105
7.5 Gaseous exchange in animals and plants
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
C
Climate change
D
Flooding of low-lying areas
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