Class:
(
Name:
22
Date:
Respiration
22.1 The basic concepts of respiration
A
)
What is respiration?
(Book 3, p. 22-3)
(Book 3, p. 22-3)
(1) ______________ (呼吸作用) is the process by which organisms release (2) ______________
from food through the controlled (3) _______________ breakdown of food.
(4) _______________ is the most common substrate for respiration.
During respiration, glucose is broken down into (5) _______________ _______________ and
(6) _______________ through a series of chemical reactions in a gradual manner. The
reactions are controlled by (7) _______________.
In each reaction, chemical energy is released. About 45% is stored in the energy carrier
(8) _______________, while the remaining 55% is lost as (9) ______________.
Overall equation of respiration:
glucose + oxygen
B
enzymes
(10) ____________ ____________ + water + energy (ATP)
What is the role of ATP in cellular metabolism?
(Book 3, p. 22-4)
During respiration, some of the energy released is used to form (11) _______________ by
combining a phosphate (P) with ADP. This process is called (12) _______________ (磷酸化).
ATP acts as an (13) _______________ _______________ in the cell in which it is made. It can
be readily broken down into ADP and phosphate with the release of a (14) _______________
(small / large) amount of energy. The ADP and phosphate released can be (15) ______________
to form more ATP during respiration.
ATP
energy from breakdown
of glucose in respiration
energy supplied
to cells
ADP + P
▲ Formation and breakdown of ATP
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Many metabolic activities in the cell are driven by energy carried by ATP. For example:
-
(16) _______________ _______________ in the uptake of food molecules in the
alimentary canal
C
-
(17) _______________ division
-
transmission of (18) _______________ _______________
-
(19) _______________ contraction
-
(20) _______________ of biomolecules, e.g. synthesis of proteins from amino acids.
What are the types of respiration? (Book 3, p. 22-5)
Respiration that requires oxygen is called (21) _______________ respiration (需氧呼吸).
Respiration that does not require oxygen is called (22) ______________ respiration (缺氧呼吸).
Compared with aerobic respiration, much (23) _______________ (more / less) ATP is formed in
anaerobic respiration and the products are (24) _______________ (the same / different).
22.2 The site of respiration
(Book 3, p. 22-6)
Both types of respiration start with the same step which occurs in the (1) _______________ of
a cell. For aerobic respiration, the remaining steps occur in the (2) _______________.
Structure of a mitochondrion:
(3) _______________
membrane
intermembrane
space
(4) _______________
(6) _______________
membrane (highly folded
____________ (線粒體基質)
and packed with
(contains enzymes)
(5) _______________)
(7) _______________ cells such as muscle cells, fat cells, liver cells and sperms contain a lot
of mitochondria.
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22.3 Aerobic respiration
(Book 3, p. 22-9)
Aerobic respiration takes place in the presence of (1) _______________. It occurs in three
main stages: (2) _______________ (糖酵解), (3) _______________ _______________
(克雷伯氏循環)
A
and (4) _______________ _______________ (氧化磷酸化).
Glycolysis (Book 3, p. 22-9)
Glycolysis occurs in the (5) _______________. It does not require (6) _______________. It
involves two main steps catalysed by enzymes in the (7) _______________.
1
Breakdown of glucose to triose phosphate
Glucose is first activated by (8) _______________, i.e. addition of phosphate groups. The
phosphate is provided by (9) _______________. During the process, (10) _______________
molecules of ATP are used and a glucose molecule is broken down into two molecules of
(11) _______________ _______________.
2
Oxidation of triose phosphate to pyruvate
Each triose phosphate molecule is (12) _______________ to a 3-C compound called
(13) _______________ (丙酮酸鹽). Two molecules of ATP are formed and triose phosphate
loses (14) _______________, i.e. becomes (15) _______________ (oxidized / reduced). The
hydrogen is accepted by a carrier molecule called (16) _______________ (nicotinamide
adenine dinucleotide 菸酰胺腺嘌呤二核苷酸). As a result, NAD is (17) _______________
(oxidized / reduced) to (18) _______________. NADH will act as a (19) _______________
donor (氫供體) in the final stage of respiration to form more ATP.
2 ATP
2 ADP + 2 P
glucose (6-C)
2 NAD
2 NADH
2 pyruvate (3-C)
2 triose phosphate (3-C)
4 ADP + 4 P
Breakdown of glucose
to triose phosphate
4 ATP
Oxidation of triose
phosphate to pyruvate
▲ An overview of glycolysis
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Bridging between glycolysis and Krebs cycle
The (20) _______________ formed in glycolysis then enters the (21) _______________
where the Krebs cycle occurs. It is first converted to a compound called
(22) ______________-______________ ______ (acetyl‑CoA 乙酰輔酶 A).
During the conversion, a (23) _______________ atom is removed from pyruvate and
released as (24) _______________ _______________. The remaining 2-C compound loses
(25) _______________ which is accepted by NAD to form (26) _______________. It then
combines with coenzyme A to form (27) _______________-_______________. Enzymes in
the (28) _______________ _______________ catalyse the conversion.
NAD NADH
pyruvate (3-C)
acetyl-CoA (2-C)
CO2
coenzyme A
For each molecule of glucose that undergoes glycolysis, (29) _______________ molecules of
acetyl-CoA are formed. Coenzyme A acts as a (30) _______________ molecule which carries
the acetyl group into the Krebs cycle.
B
Krebs cycle
(Book 3, p. 22-11)
The Krebs cycle occurs in the (31) _______________ _______________. It involves two main
steps catalysed by specific (32) _______________ in the matrix.
1
Combination of acetyl-CoA with 4-C compound
Acetyl-CoA (2-C) combines with a 4-C compound already present in the mitochondrial
matrix to form a (33) _______________ compound. In this way, coenzyme A is
(34) _______________ continually for carrying other acetyl groups formed from pyruvate into
the Krebs cycle.
CoA
acetyl-CoA (2-C) + 4-C compound
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2
Regeneration of 4-C compound
The 6-C compound is then (35) _______________ step by step to regenerate the original
4-C compound. During the process, (36) _______________ carbon atoms are removed and
released as (37) _______________ _______________. The 6-C compound also loses
(38) _______________, which is accepted by NAD to form (39) _______________.
Another carrier molecule called (40) ______________ (flavin adenine dinucleotide 黃素腺嘌呤
二核苷酸) also
accepts hydrogen to form (41) _______________. In addition, one molecule of
(42) _______________ is formed.
3 NAD 3 NADH
2 CO2
6-C compound
4-C compound
ADP + P ATP
FAD FADH
acetyl-CoA (2-C)
(converted from one of the
two molecules of pyruvate
formed in glycolysis)
coenzyme A
Combination of
acetyl-CoA with
4-C compound
4-C compound
Krebs cycle
6-C compound
Regeneration of
4-C compound
FADH
2 CO2
FAD
3 NAD
3 NADH
ATP
ADP + P
▲ An overview of the Krebs cycle
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C
Oxidative phosphorylation
(Book 3, p. 22-13)
The final stage of aerobic respiration occurs on the (43) _______________ (outer / inner)
membrane of the mitochondrion. It is called oxidative phosphorylation because the energy
for forming ATP by (44) _______________ comes from (45) _______________ of NADH and
FADH.
NADH
FADH
oxidation
oxidation
NAD +
H
+
+
e
FAD
H
+
+
e
+
–
–
releasing ATP through a
series of redox reactions
accepted by O2
H2O
▲ Oxidation of NADH and FADH and the fate of hydrogen ions and
electrons released
NADH and FADH formed in glycolysis and the Krebs cycle lose their (46) _______________
and are (47) _______________ to NAD and FAD respectively. NAD and FAD are
regenerated. They can accept (48) _______________ in glycolysis and the Krebs cycle again.
The hydrogen atoms split into (49) _______________ ions and (50) _______________.
The electrons take part in a series of (51) _______________ reactions catalysed by enzymes
embedded in the (52) _______________ (outer / inner) membrane of mitochondria. Energy is
released to form (53) _______________ in the reactions.
The hydrogen ions and electrons are eventually transferred to the final electron acceptor,
(54) _______________, to form (55) _______________.
Note: Oxidation of each NADH forms 3 ATP. Oxidation of each FADH forms 2 ATP.
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D
1
Overview of aerobic respiration
(Book 3, p. 22-14)
Energy yield in aerobic respiration
The total number of ATP formed per glucose molecule:
Number of carrier molecules
formed
Stage
Number of ATP formed
2 ATP
Glycolysis
Conversion of pyruvate
2
2 NADH
2×3=
6
2 NADH
2×3=
6
to acetyl-CoA
2 ATP
Krebs cycle
2
6 NADH
6 × 3 = 18
2 FADH
2×2=
Total number of ATP formed from the complete breakdown
4
(56) _______________
of one glucose molecule
2
Overall equation of aerobic respiration
(57) _______________ oxygen molecules are required to break down a glucose molecule
completely. (58) _______________ carbon dioxide and (59) _______________ water
molecules are released in the process, and (60) _______________ ATP is yielded.
C6H12O6 +
glucose
3
6 O2
oxygen
6 CO2 + 6 H2O + 38 ATP
carbon dioxide water
energy
Importance of oxygen in aerobic respiration
Oxygen is only used in (61) _______________ _______________. It acts as the final
(62) _______________ acceptor.
If there is no oxygen, electrons released from NADH and FADH cannot take part in the series
of redox reactions in (63) _______________ _______________. NAD and FAD cannot be
regenerated. As a result, the (64) _______________ _______________ can no longer operate
and only (65) _______________ can continue. The number of ATP formed will be greatly
(66) _______________.
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cytoplasm
Glycolysis
glucose
2 ATP
2 NADH
2 pyruvate
2 NADH
mitochondrial matrix
2 CO2
2 acetyl-CoA
Krebs cycle
6 NADH
2 ATP
4 CO2
inner
membrane of
mitochondria
2 FADH
34
ATP
Oxidative phosphorylation
H2O
O2
▲ Summary of aerobic respiration
E
Investigation of aerobic respiration in organisms
(Book 3, p. 22-17)
Carbon dioxide is a product of aerobic respiration. We can use (67) _____________________
_______________ (碳酸氫鹽指示劑) or (68) _______________ _______________ (石灰水) to
test for its production by organisms.
About 55% of energy released by respiration is lost as (69) _______________. An increase in
air (70) _______________ of the surroundings of an organism can be taken as a sign of
respiration.
Go to
Practical 22.1
Investigation of carbon dioxide production in germinating seeds
(Book 3, p. 22-17; Practical Workbook for SBA 3 • 4, p. 22-1)
Practical 22.2
Investigation of carbon dioxide production in a living mouse
(Book 3, p. 22-18; Practical Workbook for SBA 3 • 4, p. 22-4)
Practical 22.3
Investigation of heat production in germinating seeds
(Book 3, p. 22-19; Practical Workbook for SBA 3 • 4, p. 22-7)
Practical 22.4
Investigation of heat production in a living mouse
(Book 3, p. 22-20; Practical Workbook for SBA 3 • 4, p. 22-10)
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22.4 Anaerobic respiration
(Book 3, p. 22-22)
Anaerobic respiration does not require (1) _______________. The reactions of anaerobic
respiration occur in the (2) _______________ only.
Like aerobic respiration, it starts with (3) _______________ in which glucose is oxidized to
pyruvate. Without oxygen, pyruvate cannot proceed to the Krebs cycle and oxidative
phosphorylation. Instead, it follows different pathways and different products are formed.
A
Formation of ethanol and carbon dioxide in yeast (Book 3, p. 22-22)
Yeast is a unicellular (4) _______________. It respires anaerobically when the oxygen supply
is insufficient. In the process, pyruvate is reduced to an alcohol called (5) _______________.
(6) _______________ _______________ is released and (7) _______________ is regenerated
to pick up hydrogen in glycolysis again.
2 NAD
2 NADH
glucose (6-C)
2 NADH 2 NAD
2 pyruvate (3-C)
2ADP + 2 P 2 ATP
2 ethanol (2-C)
2 CO2
glycolysis
The breakdown of glucose into ethanol and carbon dioxide through anaerobic pathway is
called (8) _______________ _______________ (酒精發酵).
glucose
energy (2 ATP)
+ 2 ethanol
+ 2 carbon dioxide
During alcoholic fermentation, glucose is partially broken down to form (9) _____________
and (10) _______________ _______________.
Compared with aerobic respiration, alcoholic fermentation of one glucose molecule produces
only (11) _______________ molecules of ATP through glycolysis. A large amount of
(12) _______________ energy is still trapped inside the ethanol formed. Therefore, much
(13) _______________ (more / less) energy is released from anaerobic respiration.
Cells of certain plants can also carry out alcoholic fermentation if oxygen is in short supply.
For example, seeds and the root cells of some plants carry out alcoholic fermentation in
(14) _______________-_______________ soil.
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B
Formation of lactic acid in skeletal muscles
(Book 3, p. 22-24)
Skeletal muscle cells normally obtain energy through aerobic respiration. However, they also
carry out anaerobic respiration when there is a sudden increase in (15) _______________
need. This happens during strenuous exercise.
When a skeletal muscle cell respires anaerobically, glucose is first oxidized to
(16) _______________ in glycolysis. In the absence of oxygen, pyruvate accepts hydrogen
from NADH and is reduced to (17) _______________ _______________ (乳酸).
In this way, NAD is regenerated and can be used in glycolysis again. The lactic acid is released
into the (18) _______________.
2 NAD
2 NADH
glucose (6-C)
2 NADH 2 NAD
2 pyruvate (3-C)
2 lactic acid (3-C)
2 ADP + 2 P 2 ATP
glycolysis
The breakdown of glucose into lactic acid through anaerobic pathway is called
(19) _______________ _______________ _______________ (乳酸發酵).
glucose
energy (2 ATP)
+ 2 lactic acid
Lactic acid fermentation produces only (20) _______________
molecules of ATP through glycolysis. However, the reactions are
(21) _______________. During strenuous exercise, anaerobic
respiration is important for providing (22) _______________
energy in a very short time, so that muscles can contract more
powerfully and at a higher rate.
▲ Bicycle sprinting is
mainly an anaerobic
event
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After doing strenuous exercise, we keep breathing fast and deeply for a period of time in order
to take in extra (23) _______________. The extra oxygen is used to break down the
(24) _______________ _______________ into carbon dioxide and water, or to convert the
lactic acid to (25) _______________ in the liver. This additional amount of oxygen required to
rate of oxygen uptake
remove all the lactic acid is called the (26) _______________ _______________ (氧債).
oxygen debt
rest
exercise
recovery
rest
time
▲ Changes in the rate of oxygen uptake during and after exercise
C
Industrial application of anaerobic respiration
(Book 3, p. 22-26)
Alcoholic fermentation in yeast is used in:
-
brewing (27) _______________ and (28) _______________
-
raising (29) _______________ (麵糰) in bread-making
-
producing ethanol as (30) _______________ (生物燃料).
Lactic acid fermentation in bacteria is used in:
-
making (31) _______________
-
making (32) _______________.
Go to
Practical 22.5
Design an investigation of alcoholic fermentation in yeast
(Book 3, p. 22-23; Practical Workbook for SBA 3 • 4, p. 22-13)
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22.5 Comparison of aerobic and anaerobic respiration
(Book 3, p. 22-29)
s
Aerobic respiration
Anaerobic respiration
Release energy from the (1) _______________ breakdown of organic
substances
Similarities
Transfer energy to the energy carrier (2) _______________, and some energy
is lost as (3) _______________
Consist of a number of reactions controlled by (4) _______________
Differences
Occurs in cytoplasm and
Occurs only in
(5) _______________
(6) _______________
Oxygen is (7) _______________
Oxygen is (8) _______________
(required / not required)
(required / not required)
Organic substances are completely
Organic substances are partially
broken down into carbon dioxide
broken down to form
and (9) _______________
(10) _______________ acid or
(11) _______________ and carbon
dioxide
A (12) _______________ (smaller /
A much (13) _______________
larger) amount of energy is released
(smaller / larger) amount of energy
(38 ATP per glucose)
is released (2 ATP per glucose)
22.6 Relationship between respiration and
photosynthesis (Book 3, p. 22-30)
1
Exchange of molecules
During photosynthesis, carbon dioxide and water in the surroundings are converted to
(1) _______________ compounds which store light energy from the sun. Some of the carbon
dioxide and water is formed from (2) _______________. During respiration, the organic
compounds formed in photosynthesis are broken down to release energy for
(3) _______________ formation.
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▲ Exchange of molecules between photosynthesis and respiration
2
Flow of energy
The exchange of molecules between photosynthesis and respiration bridges the flow of
(4) _______________ from the surroundings to organisms. This also allows the flow of
energy in (5) _______________.
oxygen
glucose
sun
energy
Photosynthetic
organisms convert
photosynthesis
respiration
(6) _______________
energy to
carbon dioxide water
(7) _______________
Through respiration,
organisms break down
organic food to release
the stored energy as
(8) _______________.
energy stored in organic
food.
▲ How photosynthesis and respiration bridge the flow of energy from the surroundings to organisms
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In both photosynthesis and respiration, ATP acts as the (9) _______________ carrier.
-
In (10) _______________ (photosynthesis / respiration), ATP transfers light energy
captured by chlorophyll to make organic compounds in the (11) _______________ cycle.
-
In (12) _______________ (photosynthesis / respiration), ATP transfers the energy
released by the oxidative breakdown of organic compounds to drive cellular metabolism.
in photosynthesis
ATP
ATP
energy stored
in organic
compounds
light energy
captured by
chlorophyll
energy that
drives cellular
metabolism
ADP + P
ADP + P
in respiration
▲ Role of ATP in photosynthesis and respiration
Similarities and differences between respiration and photosynthesis:
s
Site of
occurrence
Type of
metabolism
Photosynthesis
All living cells (cytoplasm and
(13) _______________-containing
mitochondria)
cells
(14) _______________; breaks
(15) _______________; builds up
down organic food by oxidation to
organic food by reduction to store
release energy
energy
(16) _______________ energy in
(17) _______________ energy is
organic food is converted to ATP
converted to chemical energy in
and heat
organic food
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cont.
Energy
transformation
Respiration
s
Respiration
Photosynthesis
Activation process and
products formed
Both involve an activation step
Activation of glucose by
Activation of
phosphorylation using ATP
(19) ______________ by light
The activated glucose is broken
absorption
down in a controlled manner in
Electrons are excited to a high
(18) ______________ for forming
energy level
ATP and NADH
Cyclic process and products formed
Calvin cycle
Carbon dioxide is removed from
Carbon dioxide is fixed into the
(20) _______________
cycle by a (21) _______________
NADH, FADH and ATP are
compound
formed
NADPH and ATP are used to
form (22) _______________
_______________, which
subsequently forms glucose
ATP is also used to regenerate
the 5-C compound
Both involve electron transport
Energy released is used to form (23) _______________
Electron transport and formation of ATP
Reactions involved in energy transformation
Krebs cycle
Electrons in NADH and FADH
Electrons from chlorophyll are
are finally accepted by
finally accepted by
(24) _______________
(26) _______________ to form
NADPH
ATP is formed by oxidative
ATP is formed by
phosphorylation, i.e. oxidation of
(27) _______________
NADH and FADH drives ATP
formation by phosphorylation
(NADPH and ATP are used to drive
the reactions in the Calvin cycle)
ATP is also formed in glycolysis
and Krebs cycle by
(25) _______________
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Answers
Ch 22 Respiration
22.1
1
Respiration
2
energy
3
oxidative
4
Glucose
5
carbon dioxide
6
water
7
enzymes
8
ATP
9
heat
10
carbon dioxide
11
ATP
12
phosphorylation
13
energy carrier
14
small
15
reused
16
active transport
17
cell
18
nerve impulses
19
muscle
20
synthesis
21
aerobic
22
anaerobic
23
less
24
different
2
mitochondria
3
outer
4
inner
5
enzymes
7
Active
22.2
1
cytoplasm
6
mitochondrial matrix
22.3
1
oxygen
2
glycolysis
3
Krebs cycle
4
oxidative phosphorylation
5
cytoplasm
6
oxygen
7
cytoplasm
8
phosphorylation
9
ATP
10
two
11
triose phosphate
12
oxidized
13
pyruvate
14
hydrogen
15
oxidized
16
NAD
17
reduced
18
NADH
19
hydrogen
20
pyruvate
21
mitochondrion
22
acetyl-coenzyme A
23
carbon
24
carbon dioxide
25
hydrogen
26
NADH
27
acetyl-CoA
28
mitochondrial matrix
29
two
30
carrier
31
mitochondrial matrix
32
enzymes
33
6-C
34
regenerated
35
oxidized
36
two
37
carbon dioxide
38
hydrogen
39
NADH
40
FAD
41
FADH
42
ATP
43
inner
44
phosphorylation
45
oxidation
46
hydrogen
47
oxidized
48
hydrogen
49
hydrogen
50
electrons
51
redox
52
inner
53
ATP
54
oxygen
55
water
56
38
57
Six
58
Six
59
six
60
38
61
oxidative phosphorylation
62
electron
63
oxidative phosphorylation
64
Krebs cycle
65
glycolysis
66
reduced
67
hydrogencarbonate indicator
68
lime water
69
heat
70
temperature
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22.4
1
oxygen
2
cytoplasm
3
glycolysis
4
5
ethanol
6
Carbon dioxide
7
NAD
8
alcoholic fermentation
9
ethanol
10
carbon dioxide
11
two
12
chemical energy
13
less
14
water-logged
15
energy
16
pyruvate
17
lactic acid
18
blood
19
lactic acid fermentation
20
two
21
simple
22
additional
23
oxygen
24
lactic acid
25
glycogen
26
oxygen debt
27
beer / wine
28
wine / beer
29
dough
30
biofuel
31
yoghurt
32
cheese
fungus
22.5
1
oxidative
2
ATP
3
heat
4
enzymes
5
mitochondria
6
cytoplasm
7
required
8
not required
9
water
10
lactic
11
ethanol
12
larger
13
smaller
22.6
1
organic
2
respiration
3
ATP
4
energy
5
ecosystems
6
light
7
chemical
8
ATP
9
energy
10
photosynthesis
11
Calvin
12
respiration
13
Chloroplast
14
Catabolism
15
Anabolism
16
Chemical
17
Light
18
glycolysis
19
chlorophyll
20
pyruvate
21
5-C
22
triose phosphate
23
ATP
24
oxygen
25
phosphorylation
26
NADP
27
photophosphorylation
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