2. Do you know how the holes are formed?
What is the gas involved in the formation of the holes?

3. What kind of organisms in the bread produces this gas?
How does this kind of organism produce this gas?

4. In bread-making, yeast is added to the dough (生麵團)
In bread-making, yeast is added to the dough (生麵團). It produces carbon dioxide gas in anaerobic respiration (缺氧呼吸).
The gas makes the dough rise and become spongy.

5. 1) By burning 2) By respiration
8.1 How is the energy stored in food released?
2 ways:
1) By burning
2) By respiration

6. 8.1 How is the energy stored in food released?
Releasing energy by burning
When a piece of food is burnt, it reacts with oxygen.
 Oxidation (氧化作用)
food
+ O2
water + CO2
chemical energy
heat & light energy
one single step

7. 8.1 How is the energy stored in food released?
Releasing energy by burning
If glucose is burnt completely, all the energy in it will be released.
food
+ O2
water + CO2
chemical energy
heat & light energy
one single step

8. Cell releases energy in food by
8.1 How is the energy stored in food released?
Releasing energy by
respiration
Organisms do not release energy from food by burning because ……
 burning releases a large amount of heat at one time
 kill the cell
Cell releases energy in food by
respiration (呼吸作用)

9. 8.1 How is the energy stored in food released?
Releasing energy by respiration
Respiration is
 a process which organisms release energy from food through the controlled oxidative breakdown of food.
 a series of gradual and controlled chemical reactions.

10. 8.1 How is the energy stored in food released?
Releasing energy by respiration
The word equation for respiration is
glucose + oxygen
energy + CO2 + water
enzymes
can be tested by red hydrogencarbonate indicator (碳酸氫鹽指示劑) and lime water (石灰水)

11. comparison between burning and respiration
8.1 How is the energy stored in food released?
comparison between burning and respiration
heat
heat
burning
light
respiration
ATP
CO2 O2
CO2
H2O
H2O O2
glucose
glucose (in the cell)
many-step reaction & controlled by enzymes
one-step reaction
fast
gradual

12. concentration of carbon dioxide colour of hydrogencarbonate indicator
8.1
Investigation of carbon dioxide production in a living mouse
Colour of red hydrogencarbonate indicator changes with the concentration of carbon dioxide in air.
concentration of carbon dioxide
colour of hydrogencarbonate indicator
> 0.03%
Yellow
- 0.03% (atmospheric concentration)
Red / orange
< 0.03%
Purple

13. 8.1
Investigation of carbon dioxide production in a living mouse
Production of CO2 in respiration 
Procedure:
1 Set up the apparatus as shown. Note the colours of the solutions in flasks A, B and C.
air in
to suction pump
bell jar
red hydrogencarbonate indicator
potassium hydroxide solution
red hydrogencarbonate indicator
living mouse

14. 8.1
Investigation of carbon dioxide production in a living mouse
Procedure:
2 Turn on the suction pump to draw a stream of air through the apparatus for 30 minutes.
air in
to suction pump
bell jar
red hydrogencarbonate indicator
potassium hydroxide solution
red hydrogencarbonate indicator
living mouse

15. 8.1
Investigation of carbon dioxide production in a living mouse
Procedure:
3 Record any colour changes in the flask.
air in
to suction pump
bell jar
red hydrogencarbonate indicator
potassium hydroxide solution
red hydrogencarbonate indicator
living mouse

16. Investigation of carbon dioxide production in a living mouse

17. 8.1 Questions 1 Why is potassium hydroxide solution used in flask A?
Investigation of carbon dioxide production in a living mouse
Questions
1 Why is potassium hydroxide solution used in flask A?
ANS: 
To absorb carbon dioxide from the incoming air. One can deduce 推論 that any carbon dioxide detected in flask C is due to the mouse.
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18. 8.1
Investigation of carbon dioxide production in a living mouse
2 What are the functions of the red hydrogencarbonate indicator in flasks B and C?
ANS: 
Flask B: To test whether there is any carbon dioxide in the air entering the bell jar.
Flask C: To test whether there is any carbon dioxide in the air leaving the bell jar.
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19. 8.1 3 What can you tell from the result of flask B? ANS: 
Investigation of carbon dioxide production in a living mouse
3 What can you tell from the result of flask B?
ANS: 
Carbon dioxide is absent in the air entering the bell jar.
4 What can you tell from the result of flask C?
ANS: 
Carbon dioxide is released (= given out) by the mouse.
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20. 8.1 5 How would you set up a control for this practical? ANS: 
Investigation of carbon dioxide production in a living mouse
5 How would you set up a control for this practical?
ANS: 
Set up a similar apparatus (i.e. that is the same in all ways except one aspect / factor) without putting a mouse in the bell jar.
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21. Control experiment
To show that the result of an experiment is due to the factor under investigation and NOT any other factors
The three Cs : compare
change
constant
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22. Control experiment
To show that the result of an experiment is due to the factor under investigation and NOT any other factors
To show that the result of an experiment (the dependent variable) is due to the factor under investigation (the independent variable) and NOT any other factors (the controlled variables)
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23. Control experiment
To show that the result of an experiment is due to the factor under investigation and NOT any other factors
To show that the result of an experiment (the dependent variable) is due to the factor under investigation (the independent variable) and NOT any other factors (the controlled variables)
To compare
To change
To keep constant
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24. 8.1
Investigation of carbon dioxide production in a living mouse
6 What precautions should be taken if the mouse is replaced by a potted plant? Explain.
ANS: 
Wrap the pot with a plastic bag. Otherwise, carbon dioxide released by the m___________ in the soil will affect the results.
(To be continued.)
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25. 8.1 …… continued from previous page
Investigation of carbon dioxide production in a living mouse
…… continued from previous page
Cover the bell jar with a black cloth. Otherwise, the plant will absorb carbon dioxide for p__________ and this will affect the results of the respiration experiment.
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26.  8.1 X X Conclusion What conclusion can you draw from this practical?
Investigation of carbon dioxide production in a living mouse
Conclusion
What conclusion can you draw from this practical?
The mouse is living. X
ANS: 
The mouse carried out respiration. X 
The mouse produced carbon dioxide.
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27. 8.1 Conclusion What conclusion can you draw from this practical?
Investigation of carbon dioxide production in a living mouse
Conclusion
What conclusion can you draw from this practical?
ANS: 
A valid conclusion must be supported with a control and with reference to the experiment only
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28. boiled seeds (surface sterilized)
8.2
Investigation of carbon dioxide production in living germinating seeds
Procedure:
1 Set up the apparatus as shown. Leave the tubes for a few hours.
boiled seeds (surface sterilized)
soaked germinating seeds (surface sterilized)
moist cotton
wire gauze
lime water A B

29. boiled seeds (surface sterilized)
8.2
Investigation of carbon dioxide production in living germinating seeds
Procedure:
2 Record any colour changes in the lime water of tubes A and B.
boiled seeds (surface sterilized)
soaked germinating seeds (surface sterilized)
moist cotton
wire gauze
lime water A B

30. 8.2 Questions 1 What is the function of the moist cotton wool? ANS: 
Investigation of carbon dioxide production in living germinating seeds
Questions
1 What is the function of the moist cotton wool?
ANS: 
To provide the necessary amount of water for germination (種子發芽)
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31. 8.2 2 Why should the surface of the seeds be sterilized? ANS: 
Investigation of carbon dioxide production in living germinating seeds
2 Why should the surface of the seeds be sterilized?
ANS: 
To kill the micro-organisms on the surface of the seeds. Otherwise, carbon dioxide released by them during respiration will affect the results.
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32. 8.2 3 What is the reason for having a tube with boiled seeds? ANS: 
Investigation of carbon dioxide production in living germinating seeds
3 What is the reason for having a tube with boiled seeds?
ANS: 
As a control * (or control experiment) to show that only living seeds release carbon dioxide.
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33. 8.2 Conclusion What conclusion can you draw from this practical?
Investigation of carbon dioxide production in living germinating seeds
Conclusion
What conclusion can you draw from this practical?
ANS: 
The living seeds give out carbon dioxide.
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34. Brief Revision
1 ____ hydrogencarbonate indicator can be used to test for the presence of carbon dioxide.
Red
2 When the concentration of carbon dioxide is high (> 0.03%), its colour will change to ______ .
yellow
3 Besides hydrogencarbonate indicator, ____ _____ can also be used to test for the presence of carbon dioxide.
lime water

35. Places where respiration occurs in living cells
takes place in cytoplasm and mitochondria all the time
 known as “cellular respiration”

36. Places where respiration occurs in living cells
A_____ cells, e.g. muscle cells, liver cells and sperm (精子), contain a lot of mitochondria.
A sperm

37. Energy transferred to ATP and lost as heat
ATP (adenosine triphosphate 腺苷三磷酸)
 an energy carrier
Some energy released from respiration will lost as heat.

38. ATP Energy transferred to ATP and lost as heat
ATP carries a readily usable form of energy which is used for:
muscle contraction
active transport
transmitting nerve impulses (神經脈衝)
producing new materials
supporting many other biological processes

39. ATP Energy transferred to ATP and lost as heat
In some organisms, energy can be used for
 producing light (e.g. fireflies (螢火蟲))
 generating electricity (e.g. electric eels (鰻))

40. Heat Energy transferred to ATP and lost as heat
Some of the energy in food is lost as heat.
Heat
Homoitherms (恆溫動物) like birds and mammals 
make use of heat to maintain a constant body temperature.

41. coloured liquid in U-shaped capillary tube
8.3
Investigation of heat production in a living mouse
Procedure:
1 Set up the differential air thermometer as shown.
graph paper
clip
arm A
arm B
thin-walled test tube
living mouse
cotton wool
coloured liquid in U-shaped capillary tube

42. coloured liquid in U-shaped capillary tube
8.3
Investigation of heat production in a living mouse
Procedure:
2 Open the clips on both sides of the thermometer. Wait until the coloured liquid levels in arms A and B become the same.
graph paper
clip
arm A
arm B
thin-walled test tube
living mouse
cotton wool
coloured liquid in U-shaped capillary tube

43. coloured liquid in U-shaped capillary tube
8.3
Investigation of heat production in a living mouse
Procedure:
3 Close the clips. Record any changes in the liquid levels as time passes.
graph paper
clip
arm A
arm B
thin-walled test tube
living mouse
cotton wool
coloured liquid in U-shaped capillary tube

44. 8.3
Investigation of heat production in a living mouse
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45. 8.3 Questions 1 What is the function of the cotton wool? ANS: 
Investigation of heat production in a living mouse
Questions
1 What is the function of the cotton wool?
ANS: 
To prevent heat loss from the chambers.
或 to trap heat inside the chambers.
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46. 8.3 2 Why are the two clips opened at the start of the practical?
Investigation of heat production in a living mouse
2 Why are the two clips opened at the start of the practical?
ANS: 
To equalize the air pressure on both sides of the U-shaped capillary tube. This ensures that both liquid levels are the SAME (= atmospheric pressure) at the start of the practical.
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47. 8.3
Investigation of heat production in a living mouse
3 Explain the results.
● Heat is produced by the mouse and it warms up the air in the thin-walled test tube. ● The air in the test tube expands and results in an increase in air pressure. ● This pushes the air out of the test tube and hence forces the liquid level in arm B downwards.
(To be continued.)
ANS: 
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48. 8.3 …… continued from previous page
Investigation of heat production in a living mouse
…… continued from previous page
Since there is no temperature change in the control (the side without the mouse), the falling of the liquid level in arm B leads to a rise of the liquid level in arm A.
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49. 8.3
Investigation of heat production in a living mouse
4 Can the practical be carried out for a long time? Why?
ANS: 
No. It is because the mouse will use up all the oxygen inside the chamber and die.
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50. 8.3
Investigation of heat production in a living mouse
5 Which capillary tube, one with a wide bore (闊口徑) or a narrow bore, is more suitable for this practical? Why?
ANS: 
A capillary tube with a narrow bore is more suitable for this practical because small change can be obviously recorded.
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51. 8.3
Investigation of heat production in a living mouse
6 How will the results differ if the mouse is replaced by a frog of the same size?
ANS: 
The change in liquid level is smaller. The frog, being a poikilotherm, has a lower metabolic rate and less heat is released from its body.
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52. 8.3 Conclusion What conclusion can you draw from this practical?
Investigation of heat production in a living mouse
Conclusion
What conclusion can you draw from this practical?
ANS: 
Heat is produced by the living mouse.
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53. 8.4 Try to design an experiment to test your hypothesis. Experiment
Design an investigation of heat production in living germinating seeds
From Practical 8.3, we know that a living mouse produces heat when it carries out respiration. Is there any heat production in geminating seeds as well?
Try to design an experiment to test your hypothesis.
Experiment

54. Aerobic respiration 8.2 What are the types of respiration?
 requires oxygen
 takes place in cytoplasm and mitochondria
 glucose is completely broken down into carbon dioxide and water
 a large amount of energy can be transferred to ATP molecules

55. Anaerobic respiration
8.2 What are the types of respiration?
Anaerobic respiration
Anaerobic respiration (缺氧呼吸)
 can happen without oxygen
 it takes place only in cytoplasm but not in mitochondria
 glucose is only partly broken down
 much less energy is released

56. 8.5
Demonstration of anaerobic respiration in germinating seeds
Procedure:
1 Put the seeds into a boiling tube and then a piece wire gauze. Fill the tube with paraffin oil.
boiling tube
wire gauze
soaked germinating seeds (surface sterilized)

57. 8.5
Demonstration of anaerobic respiration in germinating seeds
Procedure:
2 Invert the tube and insert it into a container of paraffin oil. Do not trap any air between the seeds and the oil.
paraffin oil

58. 8.5
Demonstration of anaerobic respiration in germinating seeds
Procedure:
3 Leave the tube for a few hours and record the change in oil level. Collect the gas as shown.
push the plunger to collect the gas
syringe
gas collected
plastic tube

59. 8.5
Demonstration of anaerobic respiration in germinating seeds
Procedure:
4 Bubble the gas through red hydrogencarbonate indicator as shown.
push the plunger to collect the gas
gas collected
red hydrogencarbonate indicator

60. alcoholic fermentation (酒精發酵)
8.2 What are the types of respiration?
Anaerobic respiration
Alcoholic fermentation in yeast
Glucose is broken down anaerobically into ethanol (乙醇) and carbon dioxide.
glucose
energy (in ATP) + ethanol + CO2
enzymes
alcoholic fermentation (酒精發酵)

61. 8.6 Design an investigation of alcoholic fermentation in yeast
A king stored grapes in a jar. One day, he opened the jar and a strange smell came out. He labelled the jar ‘poison’ and put it aside. A servant drank the ‘poison’ by mistake. She found it tasty.
The ‘poison’ was actually made by alcoholic fermentation carried out by yeast growing naturally on grape skins.
Try to design and perform an experiment to recreate the same process.

62. Anaerobic respiration
1) Beer production
Yeast is added to malt (麥芽).
 yeast respires without oxygen
 turns the sugar in malt into alcohol
 add hops (蛇麻草) to give beer a pleasant bitter taste

63. Anaerobic respiration
2) Wine production
Wine is made from grape juice.
1) Grapes contain a lot of sugars.

64. Anaerobic respiration
2) Wine production
2) The grapes are crushed.

65. Anaerobic respiration
2) Wine production
grape juice
3) Crushed grapes are processed and filtered.

66. Anaerobic respiration
2) Wine production
4) Grape juice is fermented by yeast to produce alcohol and carbon dioxide.

67. Anaerobic respiration
2) Wine production
5) Fermented grape juice is put into barrels and kept to develop a good flavour.

68. Anaerobic respiration
2) Wine production
6) The wine is put into bottles and tightly corked to prevent further oxidation.

69. Anaerobic respiration
3) Bread-making
Bread-making makes use of carbon dioxide.
1) The ingredients above are mixed to form a dough.

70. Anaerobic respiration
3) Bread-making
2) The dough is pressed and stretched to the shape of a loaf.

71. Anaerobic respiration
3) Bread-making
3) The dough is covered and put in a warm place.

72. Anaerobic respiration
3) Bread-making
4) The carbon dioxide produced by the alcoholic fermentation of yeast makes the dough spongy.

73. Anaerobic respiration
3) Bread-making
5) The spongy dough is baked in an oven. The dough rises more when the carbon dioxide expands at higher temperature. The alcohol evaporates.

74. Anaerobic respiration
3) Bread-making
6) The bread is ready to serve.

75. Anaerobic respiration
8.2 What are the types of respiration?
Anaerobic respiration
Lactic acid production in muscles
In humans, some skeletal muscles can respire anaerobically and contract even when oxygen is insufficient.
 to provide additional energy in a very short time

76. Anaerobic respiration
8.2 What are the types of respiration?
Anaerobic respiration
Lactic acid production in muscles
 lactic acid is produced
glucose
energy (in ATP) + lactic acid
enzymes
 results in muscle fatigue (肌肉疲勞) and cause pain

77. Anaerobic respiration
8.2 What are the types of respiration?
Anaerobic respiration
Lactic acid production in muscles
 After doing strenuous exercise, one has to breathe deeply for a period of time to take in extra oxygen.

78. Anaerobic respiration
8.2 What are the types of respiration?
Anaerobic respiration
Lactic acid production in muscles
 to break down the lactic acid into carbon dioxide and water or convert it to glucose

79. Anaerobic respiration
8.2 What are the types of respiration?
Anaerobic respiration
Lactic acid production in muscles
 This extra amount is called the oxygen debt (氧債).

80. 8.3 What is the importance of anaerobic respiration during exercise?
Extension
8.3 What is the importance of anaerobic respiration during exercise?

81. 8.2 Degree of dependence on anaerobic respiration of different sports
 Try to find out which system is the major energy source for different sports.
Go to Activity Book 1, p.144

82. Brief Revision
1 Yeast undergoes anaerobic respiration to produce energy, ______ ______ and _______ .
carbon dioxide
ethanol
2 In muscles, anaerobic respiration will produce energy and _____ ____ .
lactic acid
3 Accumulation of lactic acid in the muscles will result in ______ ______ and cause pain.
muscle fatigue

83. Brief Revision
4 In order to break down the lactic acid in the muscles, one has to take in extra oxygen. This extra amount is called ______ _____.
oxygen debt
5 In cytoplasm, only anaerobic respiration can take place. True or false?
False. Both anaerobic and some reactions in aerobic respirations can take place in cytoplasm.

84. Brief Revision
6 Aerobic and anaerobic respirations can take place at the same time in the muscles. True or false?
True. Anaerobic respiration can give extra energy at the same time when needed.

85. Summary concept diagram
Respiration
can be is
releases
a series of
reactions
chemicals
energy in food
anaerobic
respiration
aerobic
respiration
take place in
does not require
requires
transferred to
lost as
ATP
heat
oxygen
cytoplasm
mitochondria

86. Back to summary concept diagram
anaerobic
respiration
examples are
alcoholic
fermentation
in yeast
lactic acid
production
in muscles
used in
leads to
oxygen debt
and fatigue
beer
production
wine
production
bread-making
Back to summary concept diagram