7.5 GASEOUS EXCHANGE IN ANIMALS AND PLANTS
Does the food really
burn in our body?
peanut
Food has to be burnt
to release energy.
7.5 GASEOUS EXCHANGE IN ANIMALS AND PLANTS
7.5 GASEOUS EXCHANGE IN ANIMALS AND PLANTS
BODY CELL
A
B
food
RESPIRATION
oxygen
7.5 GASEOUS EXCHANGE IN ANIMALS AND PLANTS
C
We can summarise the
process of respiration in a
simple word equation.
food + oxygen
carbon
+ water +
dioxide
ENERGY
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
XPERIMENT 7.18
(p.56)
Gaseous exchange in plants
Materials and apparatus
stoppers
4
boiling tubes
4
table lamp
1
test tube rack
1
green leaves
2
thread
about 50 cm
about 20 cm3
hydrogencarbonate indicator
2
aluminium foil
7.5 GASEOUS EXCHANGE IN ANIMALS AND PLANTS
1. Set up the apparatus as shown in the diagram
on the right.
aluminium foil
leaves
A
B
C
D
hydrogencarbonate indicator
7.5 GASEOUS EXCHANGE IN ANIMALS AND PLANTS
2. Leave the boiling tubes in bright light for
about one hour. Then record the colour of the
indicator.
Boiling tube
At the beginning
After 1 hour
A
B
C
D
Which tubes are used as the control? _______
7.5 GASEOUS EXCHANGE IN ANIMALS AND PLANTS
This exchange of oxygen and
carbon dioxide is called
gaseous exchange.
Experiment 7.15
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
Gaseous exchange
in plants
7.5 GASEOUS EXCHANGE IN ANIMALS AND PLANTS
Activity 7 (e)
Feeling dizzy in a plant house
Eric likes plants very much. His house is fully
decorated with green plants.
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
XPERIMENT 7.18
Gaseous exchange in plants
Materials and apparatus
stoppers
4
boiling tubes
4
table lamp
1
test tube rack
1
green leaves
2
thread
about 50 cm
about 20 cm3
hydrogencarbonate indicator
2
aluminium foil
7.5 GASEOUS EXCHANGE IN ANIMALS AND PLANTS
1. Set up the apparatus as shown in the diagram
on the right.
aluminium foil
leaves
A
B
C
D
hydrogencarbonate indicator
7.5 GASEOUS EXCHANGE IN ANIMALS AND PLANTS
2. Leave the boiling tubes in bright light for
about one hour. Then record the colour of the
indicator.
Boiling tube
At the beginning
After 1 hour
A
B
C
D
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
Colour of the
indicator
= 0.03%
> 0.03%
< 0.03%
(normal air)
yellow
7.5 GASEOUS EXCHANGE IN ANIMALS AND PLANTS
Orange red
purple
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 out
photosynthesis : take in
carbon dioxide and
produce oxygen.
Do green plants really
release oxygen
ALL the time
Activity 7(e)
Experiment 7.18
7.5 GASEOUS EXCHANGE IN ANIMALS AND PLANTS
In day time, green plants carry out
photosynthesis.
photosynthesis
7.5 GASEOUS EXCHANGE IN ANIMALS AND PLANTS
Remember that green plants
respire BOTH day and night.
respiration
7.5 GASEOUS EXCHANGE IN ANIMALS AND PLANTS
At night, photosynthesis
stops(why?) and only respiration
occurs.
respiration
7.5 GASEOUS EXCHANGE IN ANIMALS AND PLANTS
• http://www.bbc.co.uk/schools/gcsebitesize/
biology/greenplantsasorganisms/0photosy
nthesisrev6.shtml
7.5 GASEOUS EXCHANGE IN ANIMALS AND PLANTS
oxygen
carbon dioxide
in air
oxygen
carbon
dioxide
oxygen
respiration
photosynthesis > respiration
carbon dioxide
Net uptake: Gas A
Net uptake: Gas A
Net release: Gas B
Net release: Gas B
Under bright sunlight
At night
Rate of
photosynthesis
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 _________.
7.5 GASEOUS EXCHANGE IN ANIMALS AND PLANTS
Homework
w/b 2A
• P.11(part A 1, 2,4,5)
• P.13(1)
• P.15(B)
• P.17(1-5, 7)
• P.18-19(1-5)
• P.20(7)
• P.21-23(1,3,4)
• P.24(6)
7.5 GASEOUS EXCHANGE IN ANIMALS AND PLANTS