7.5 Gaseous exchange in animals and plants 1
Gaseous exchange in animals and plants
7.7.55
7.5 Gaseous exchange in animals and plants 2
RespirationUnbreathed air
nitrogen (78%)
oxygen (21%) carbon dioxide
(0.03%)
7.5 Gaseous exchange in animals and plants 3
RespirationBreathed air
nitrogen (78%)oxygen (21%)
carbon dioxide (0.03%)
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RespirationBreathed airUnbreathed air
less oxygen
more carbon dioxide
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Respiration
living cell
oxygen
break down food energy
support body activities
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food + oxygen
carbon dioxide+ water + energy
Respiration
Word equation of respiration:
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Gaseous exchange in animals
gaseous exchange (氣體交換 )
oxygen in aircarbon dioxide in air
taken inremove carbon dioxide from the body
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Gaseous exchange in mealworms7.15 Experiment
video
1
mealworm
wire gauze
soda lime
capillary tube
colour marker
A
B
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7.15a In what way is tube B different from
tube A?
There is no mealworm in tube B.
A
B
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7.15b What is the purpose of setting up
tube B?
B
A
To eliminate the changes in the set-ups caused by changes in environmental factors, such as airtemperature and pressure.
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2
A
B
Measure this distance
7.15
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2
Tube
Distance between the colour marker
and the stopper (cm)
At the beginning 20 minutes later
A
B
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Discussion
1 Which tube contains less gas at the end of the experiment?
Tube A.
7.15
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The mealworms take in ________and give out ______________. The ______________ is absorbed by soda lime.
oxygen
2 Try to explain the result in tube A.
carbon dioxidecarbon dioxide
7.15
7.5 Gaseous exchange in animals and plants
The gas pressure inside tube A therefore ___________ and becomes ___________ than the atmospheric pressure.
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decreaseslower
7.15
As a result, the colour marker _____________________________is pushed towards the boiling
tube.
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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. Thisaffects the experimental results.
7.15
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The human respiratory system
Humans and most animals have a respiratory system (呼吸系統 ) for gaseous exchange.
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Major parts of our respiratory system
7.16 3D model
Identify the major parts of the respiratory system.
Label the diagram.
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nasal cavity
trachea
bronchus
bronchiole
7.16
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air sac
intercostal muscle
rib
lung
diaphragm
7.16
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The human respiratory system
nostrilsair
nasal cavity
trachea
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The human respiratory system
bronchiair
bronchioles
air sacs
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The human respiratory system
lungs are protected by the rib cage (肋骨籃 )
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The human respiratory system
backbone
rib chest bone
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The human respiratory system
diaphragm
intercostal muscles
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Gaseous exchange in the air sac
3D animation
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Gaseous exchange in the air sac
oxygen
carbon dioxide
direction of blood flow
capillary
air sac
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The breathing mechanism
Do you know how breathing is brought about?
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7.4Feeling your breath
Take a deep breath.
Feel the movement of your ribs.
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7.4
They move upwards and outwards.
a Which way do your ribs move when you breathe in?
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7.4b Which way do your ribs move when
you breathe out?
They move downwards and inwards.
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The breathing mechanismMovements are brought by the actions of …
intercostal muscles
diaphragm
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a Breathing in
intercostal muscles
diaphragm
lungrib
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a Breathing in
1a Intercostal muscles contract.
Ribs move upwards and outwards. 1b Diaphragm
flattens.
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a Breathing in
Gas pressure inside it decreases.
2 Volume of chest cavity
increases.
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a Breathing in
3 Air is drawn in.
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b Breathing out
1a Intercostal muscles relax.
Ribs move downwards and inwards.
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b Breathing out
1b Diaphragm returns to dome shape.
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b Breathing out
Gas pressure inside it increases.
2 Volume of chest cavity decreases.
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b Breathing out
3 Air is forced out.
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Using a model to show the action of the intercostal muscles during breathing
7.17 Animation
rib cage model (肋骨籃模型 )
rubber bandA
BC
B1
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A
BC
B
Each part represents…
ribs
chest bonebackbone
intercostal muscles
17.17
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2
F
G
D
H
E
Position X
I
measure this length
7.17
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3
L
MJN
KO
measure this length
Position Y
7.17
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4 Which rubber band, HI or NO, is shorter in length?
NO. H
I
N
O
7.17
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5 In which case, position X or Y, are the intercostal muscles contracting?
Position X Position Y
7.17
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6 Which parallelogram, DEFG or JKLM, is larger in area?
F
G
D
E
L
MJ
K
7.17
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7 In which case, position X or Y, is the chest volume greater?
Position X Position Y
7.17
7.5 Gaseous exchange in animals and plants
8 When the model is set from position X to position Y, the rubber band becomes ___________. This represents the intercostal muscles are ___________.
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shortened
contracting
7.17
7.5 Gaseous exchange in animals and plants
The ribs, move __________ and the chest volume __________. This is similar to the situation when we are breathing __________.
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in
7.17
upwardsincreases
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Using a model to show the action of the diaphragm during breathing
7.18 Animation
balloon-bell jar model
(氣球及鐘形罩模型 )
1 glass tube
Y-piece
balloons
rubber sheet
7.5 Gaseous exchange in animals and plants
Each part represents…
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1
trachea
bronchi
lungs
diaphragm
7.18
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27.18
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27.18
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3 What happens to the balloons when the rubber sheet is pulled down?
The balloons become _______.bigger
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7.5 Gaseous exchange in animals and plants
When the rubber sheet is pulled down, the volume of the bell jar __________ and the gas pressure inside the bell jar becomes __________.
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increases
lower
3
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7.5 Gaseous exchange in animals and plants
Therefore air flows ________ the balloons. This is similar to the situation when we are breathing ________.
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in
3
7.18
into
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4 What happens to the balloons when the rubber sheet is pushed up?The balloons become ________.smaller
7.18
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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.
7.18
7.5 Gaseous exchange in animals and plants
This is similar to the situation when we are _____________.
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4breathing out
7.18
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In humans, gaseous exchange takes place in the ________.
Gaseous exchange in animals
air sacs
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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 musclesdiaphragm
7.5 Gaseous exchange in animals and plants
At the same time, the diaphragm becomes _________.
1 When we breathe in, the intercostal muscles _________.
The ribs move _________ and __________.
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55
upwards
contract
outwards
flattened
7.5 Gaseous exchange in animals and plants
These movements cause the volume of the chest cavity to
_________ and therefore the gaspressure inside it ___________. Air is then drawn into the lungs.
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551
increasedecreases
7.5 Gaseous exchange in animals and plants
lung
2 Which photo, A or B, was taken when the man was breathing out? Why?
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55
A B
rib
heart
diaphragm
diaphragm is dome-shaped
Well done!
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Gaseous exchange in plantsGreen plants
oxygen
carbon dioxide
Photosynthesis
take in
give out
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Gaseous exchange in plantsGreen plantsRespiration
oxygen
carbon dioxide
take in
give outtake in
give out
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Gaseous exchange in plantsGreen plants
oxygen and carbon dioxide: uptake or release?
In a day…
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Gaseous exchange in plantsGreen plantsDepends on the rates
of photosynthesis and respiration
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When do green plants take in and give out carbon dioxide?
7.19 Experiment video
hydrogencarbonate indicator
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7.19
Concentration ofcarbon dioxide
> 0.03%~ 0.03%(normal
level in air)< 0.03%
Colour ofhydrogen-carbonateindicator
Yellow Red Purple
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7.191
green leaves
aluminium foil
each tube contains 3 cm3 of hydrogencarbonate indicatorA B C D
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a What is the purpose of setting up tube B?
A B C D
To make sure that the result in tube A is caused by the presence of the green leaf.
7.19
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b What is the purpose of setting up tube D?
A B C D
To make sure that the result in tube C is caused by the presence of the green leaf.
7.19
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2
A B C D
leave for one hour
7.19
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2
A B C D
represent in the daytime
represent at night
7.19
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Tube
Colour of the hydrogencarbonate indicator
At the beginning After one hour
A Red
B Red
C Red
D Red
3
Purple
Red
Yellow
Red
7.19
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4a Compare the results in tube A and tube B. What does the difference show?
Tube A Tube B
7.19
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4a Compare the results in tube A and tube B. What does the difference show?
Tube A Tube BThe green leaf takes in carbon dioxide from the air in the presence of light.
7.19
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b Compare the results in tube C and tube D. What does the difference
show?
Tube C Tube D
7.19
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b Compare the results in tube C and tube D. What does the difference
show?
Tube C Tube DThe green leaf gives out carbon dioxide in the dark.
7.19
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Gaseous exchange in plants
In the daytimerate of
photosynthesis
rate of respiration
higher than
net uptake of carbon dioxide
net release of oxygen
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Gaseous exchange in plants
At night
photosynthesis stops
respiration continues
net release of carbon dioxide
net uptake of oxygen
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In the daytime, there is a net release of oxygen and a netuptake of carbon dioxide in green plants.
Gaseous exchange in plants
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Gaseous exchange in plants
At night, green plants take in oxygen and give out carbon dioxide.
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The balance of oxygen and carbon dioxide in nature
oxygen in air
carbon dioxide in air
photosynthesis of green plants
respiration of animals and plantstaken up
during
releases oxygen
releases carbon dioxide
taken up during
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Living things carry out respiration. Green plants carry out photosynthesis.
The balance of oxygen and carbon dioxide in nature
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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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The effect of the increasing amount of carbon dioxide in the atmosphere on us
atmosphereEarth
Sun
Animation
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The greenhouse effect
1 Sunlight passes through the atmosphere and reaches the Earth.
1
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The greenhouse effect
2 Heat energy is reflected back from the Earth’s surface.
2
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The greenhouse effect
3a Some heat energy is lost to space.
3a
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The greenhouse effect3b Some heat energy is absorbed by
some gases in the atmosphere, leading to greenhouse effect.
3b
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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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The effect of the increasing amount of carbon dioxide in the atmosphere on us
amount of carbon dioxide absorbed during photosynthesis drops
large areas of forests are cleared
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amount of carbon dioxide in the atmosphere increases
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amount of carbon dioxide in the atmosphere increases
traps more heat and enhances greenhouse effect
average temperatures of the Earth keep increasing
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amount of carbon dioxide in the atmosphere increases
traps more heat and enhances greenhouse effect
average temperatures of the Earth keep increasing
global warming (全球增温 )
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Global warming
speeds up the melting of ice at polar regions
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Global warming
speeds up the melting of ice at polar regions
living things at polar regions may lose their habitats
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Global warming
speeds up the melting of ice at polar regions
sea level rises
flooding of low-lying areas
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Global warming
causes climate changes
more frequent droughts and storms
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The increasing amount of carbon dioxide in the atmosphere enhances the greenhouse effect.
The effect of the increasing amount of carbon dioxide in the atmosphere on us
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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.
7.5 Gaseous exchange in animals and plants
1 Which of the following leads to global warming?
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A The atmospheric temperature rises continuously.
D The amount of carbon dioxide in the atmosphere increases.
C The amount of carbon dioxide in the atmosphere decreases.
B The amount of oxygen in the atmosphere decreases.
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A An increase in the amount of oxygen in the atmosphere
D Flooding of low-lying areas
C Climate change
B Melting of ice capsExcellent!
2 Which of the following is not likely to be caused by global warming?