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7.5 GASEOUS EXCHANGE IN ANIMALS AND PLANTS
peanut
Food has to be Food has to be burntburnt to to release energyrelease energy..
Food has to be Food has to be burntburnt to to release energyrelease energy..
Does the food really burn in our
body?
Does the food really burn in our
body?
7.5 GASEOUS EXCHANGE IN ANIMALS AND PLANTS
We can summarise the process of respiration in a sim
ple word equation.
We can summarise the process of respiration in a sim
ple word equation.
foodfood oxygenoxygencarbon carbon dioxidedioxide waterwater++ ++ ++ ENERGY
Where does the oxygen required for respiration is
obtained? How is it transported to the body cells?
Where does the oxygen required for respiration is
obtained? How is it transported to the body cells?
7.5 GASEOUS EXCHANGE IN ANIMALS AND PLANTS
Gaseous exchange in plants
XPERIMENT 7.18 (p.56)
Materials and apparatusboiling tubestest tube rackthreadhydrogencarbonate indicatoraluminium foil
41
about 50 cm
412
about 20 cm3
2
stopperstable lampgreen leaves
7.5 GASEOUS EXCHANGE IN ANIMALS AND PLANTS
aluminium foil
hydrogencarbonate indicator
leaves
A B C D
1.Set up the apparatus as shown in the diagram on the right.
7.5 GASEOUS EXCHANGE IN ANIMALS AND PLANTS
Boiling tube At the beginning After 1 hour
A
B
C
D
2.Leave the boiling tubes in bright light for about one hour. Then record the colour of the indicator.
Which tubes are used as the control? _______
7.5 GASEOUS EXCHANGE IN ANIMALS AND PLANTS
Gas AGas A
Gas BGas B
This exchange of oxygen and This exchange of oxygen and carbon dioxide is called carbon dioxide is called gaseous exchangegaseous exchange..
Experiment 7.15Experiment 7.15 Do you know?Do you know?
7.5 GASEOUS EXCHANGE IN ANIMALS AND PLANTS
Experiment 7.15
• Step 1 : Tube B is a control experiment. Why?
• http://aero.spss.edu.hk/~ilau/I.S./chapter%207/
7.5 GASEOUS EXCHANGE IN ANIMALS AND PLANTS
Gaseous exchange in animals
• Animals obtain energy in a process called _______________.
• Animals take in _________ and give out _______ during breathing.
7.5 GASEOUS EXCHANGE IN ANIMALS AND PLANTS
Eric likes plants very much. His house is fully decorated with green plants.
Activity 7 (e)
Feeling dizzy in a plant house
I like green plants very much. They make me healthy by providing me with a large amount of oxygen.
I like green plants very much. They make me healthy by providing me with a large amount of oxygen.
7.5 GASEOUS EXCHANGE IN ANIMALS AND PLANTS
One night, Eric slept in his house with all the windows closed. He felt dizzy in the next morning.
What is the possible reason that makes Eric feel dizzy? Discuss with your classmates to find it out.
7.5 GASEOUS EXCHANGE IN ANIMALS AND PLANTS
Gaseous exchange in plants
XPERIMENT 7.18
Materials and apparatusboiling tubestest tube rackthreadhydrogencarbonate indicatoraluminium foil
41
about 50 cm
412
about 20 cm3
2
stopperstable lampgreen leaves
7.5 GASEOUS EXCHANGE IN ANIMALS AND PLANTS
aluminium foil
hydrogencarbonate indicator
leaves
A B C D
1.Set up the apparatus as shown in the diagram on the right.
7.5 GASEOUS EXCHANGE IN ANIMALS AND PLANTS
Boiling tube At the beginning After 1 hour
A
B
C
D
2.Leave the boiling tubes in bright light for about one hour. Then record the colour of the indicator.
Which tubes are used as the control? _______
7.5 GASEOUS EXCHANGE IN ANIMALS AND PLANTS
The table below shows the colours of hydrogencarbonate indicator in the presence of different concentrations of carbon dioxide.
Concentration of carbon dioxide
> 0.03%= 0.03%
(normal air)< 0.03%
Colour of the indicator
yellow Orange red purple
7.5 GASEOUS EXCHANGE IN ANIMALS AND PLANTS
Expt. 7.18-video
• http://aero.spss.edu.hk/~ilau/I.S./chapter%207/
7.5 GASEOUS EXCHANGE IN ANIMALS AND PLANTS
Explain the results in tube A.
The leaf in tube A carries out both photosynthesis and respiration. The rate of _____________ is higher than that of __________. As _____________ needs carbon dioxide, the concentration of carbon dioxide in tube A is __________. The indicator turns __________.
7.5 GASEOUS EXCHANGE IN ANIMALS AND PLANTS
Explain the results in tube B.
As light is blocked by the aluminium foil, the leaf in tube B does not carry out ____________. It only carries out ____________, ____________ is given out and its concentration ___________ (increases / decreases). Then, the indicator turns _________.
7.5 GASEOUS EXCHANGE IN ANIMALS AND PLANTS
Green plants can carry outGreen plants can carry outphotosynthesisphotosynthesis : take in : take in carbon dioxide and carbon dioxide and produce oxygenproduce oxygen..
Do green plants reallyDo green plants reallyrelease oxygenrelease oxygen ALL the timeALL the time
Do green plants reallyDo green plants reallyrelease oxygenrelease oxygen ALL the timeALL the time
Activity 7(e)Activity 7(e) Experiment 7.18Experiment 7.18
7.5 GASEOUS EXCHANGE IN ANIMALS AND PLANTS
In day time, green plants carry out In day time, green plants carry out photosynthesisphotosynthesis..
photosynthephotosynthesissis
carbon
dioxide
carbon
dioxide
carbon dioxide
carbon dioxidecarbon
dioxidecarbon
dioxide
oxygen
oxygenoxygenoxygen
oxygen
oxygen
7.5 GASEOUS EXCHANGE IN ANIMALS AND PLANTS
Remember that green green plants plants respirerespire BOTH day BOTH day
and night.and night.
Remember that green green plants plants respirerespire BOTH day BOTH day
and night.and night.
oxygen
oxygenoxygenoxygen
carbon
dioxide
carbon
dioxidecarbon
dioxidecarbon
dioxide
respirationrespiration
7.5 GASEOUS EXCHANGE IN ANIMALS AND PLANTS
At night, photosynthesis stops(wAt night, photosynthesis stops(why?) and hy?) and only respirationonly respiration occurs. occurs.
respiratiorespirationn
oxygen
oxygenoxygenoxygen
oxygen
oxygen
carbon
dioxide
carbon
dioxide
carbon dioxide
carbon dioxidecarbon
dioxidecarbon
dioxideGaseous exchange in
green plants in the day
time is ________from
that at night.
Gaseous exchange in
green plants in the day
time is ________from
that at night.
7.5 GASEOUS EXCHANGE IN ANIMALS AND PLANTS
• http://www.bbc.co.uk/schools/gcsebitesize/biology/greenplantsasorganisms/0photosynthesisrev6.shtml
7.5 GASEOUS EXCHANGE IN ANIMALS AND PLANTS
Under bright sunlight At night
photosynthesis > respiration
carbon dioxidein air
carbon dioxide
oxygen
oxygen
respiration
oxygencarbon dioxide
Rate of photosynthesis
Rate of photosynthesis
Net uptake: Gas A
Net release: Gas B
Net uptake: Gas A
Net release: Gas B
7.5 GASEOUS EXCHANGE IN ANIMALS AND PLANTS
What have you learnt in this lesson?
• Under bright sunlight, there is a net uptake of _______and a net release of _________ by green plants.
• At night, green plants only release _______ and take in _________.