7.5 GASEOUS EXCHANGE IN ANIMALS AND PLANTS. peanut Food has to be burnt to release energy. Does the food really burn in our body?

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?



BODY CELL

oxygen

food

RESPIRATION

B

C

A


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?


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


aluminium foil

hydrogencarbonate indicator

leaves

A B C D

1.Set up the apparatus as shown in the diagram on the right.


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? _______


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?


Experiment 7.15

• Step 1 : Tube B is a control experiment. Why?

• http://aero.spss.edu.hk/~ilau/I.S./chapter%207/


Gaseous exchange in animals

• Animals obtain energy in a process called _______________.

• Animals take in _________ and give out _______ during breathing.


Gaseous exchange Gaseous exchange in plantsin 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.


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.


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


aluminium foil

hydrogencarbonate indicator

leaves

A B C D

1.Set up the apparatus as shown in the diagram on the right.


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? _______


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


Expt. 7.18-video

• http://aero.spss.edu.hk/~ilau/I.S./chapter%207/


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 __________.


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 _________.


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


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


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


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.


• http://www.bbc.co.uk/schools/gcsebitesize/biology/greenplantsasorganisms/0photosynthesisrev6.shtml


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


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 _________.


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)

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7.5 GASEOUS EXCHANGE IN ANIMALS AND PLANTS. peanut Food has to be burnt to release energy. Does the food really burn in our body?