1. CHAPTER 7 :
RESPIRATION
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2. 2

3.  State that all living processes require energy
 Identify the main substrate for producing energy
 State the two types of respiration
 Explain what cell respiration is
 Explain the energy production from glucose during the
process of aerobic respiration
 State the conditions leading to anaerobic respiration in
cells
 Explain the process of anaerobic respiration in human
muscles
 Write the chemical equations for aerobic & anaerobic
respiration
 Compare & contrast aerobic respiration with anaerobic
respiration
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4.  All organisms require energy to carry out all
living processes  growth (cell division),
reproduction (meiosis), response (transmitting
impulses), movement (contraction of muscle),
breathing, digestion & excretion (synthesis of
proteins, hormones, lipids & enzymes)
 RESPIRATION : the metabolic process in
which organic molecules broken down to
simpler products with the release of
chemical energy for other living processes.
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5.  Occurs in two stage :
 External respiration – a mechanical process that
maintains a continuous exchange of gases between the
respiratory surfaces of an organisms & its environment
 Internal respiration (cellular respiration) – the
biochemical process in which energy is made available to
all living cells
 The main substrate : glucose (obtain from digestion of
carbohydrates & photosynthesis)
 Occurs in mitochondria & cytoplasm of cells
 Involves a series of reactions controlled by enzymes
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6. TYPES OF RESPIRATION
 AEROBICRESPIRATION
 ANAEROBIC RESPIRATION
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7. AEROBIC RESPIRATION
 The breaking down of glucose in the
presence of oxygen to release chemical
energy
 Oxygen is required to oxidise the glucose
to produce CO2, H2O & energy
 The glucose is completely oxidised to
release all the chemical energy in the
glucose
 Occurs in mitochondria & cytoplasm of
cells
 Slowly occurs & in stages controlled by
enzymes.
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8.  The energy is released in stages & in small
amounts
 Some chemical energy released in changed to
heat energy while the rest of the chemical
energy released is stored in a form of ATP, a
carrier of chemical energy
 ATP can e regenerated by combining inorganic
phosphate (P) to ADP using the chemical energy
obtained from the oxidation of food
 ATP ↔ ADP + P + energy
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9.  When body cells need energy, ATP
molecules will be hydrolysed to yield
energy, a molecule energy & an inorganic
phosphate
 Energy from ATP can be used to carry out
biological process
Glucose + oxygen  carbon dioxide + water + energy
C6H12O6 + 6O2  6CO2 + 6H20 + 38 ATP (2898 kJ)
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10. A N A E R O B IC
R E S P IR A T IO N
 A type of cell respiration which occurs in
the absence of oxygen to release energy
 Glucose is not completely broken down 
not all energy in glucose is released
 Some of the energy in glucose is stored in
the product of anaerobic respiration  2
ATP is released
 Occurs in cytoplasm
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11. ANAEROBIC RESPIRATION IN HUMAN
MUSCLES
 Occurs during vigorous exercise @ vigorous activities
(100m sprint).
 Oxygen need to be transported fast enough to the
muscles for rapid cell respiration. Will enable the
release of sufficient energy for the vigorous muscle
activity.
 The breathing rate & heart rate are increased to
supply more oxygen quickly to the muscles for rapid
muscular contraction
 Still insufficient  have to carry out anaerobic
respiration to release energy
C6H12O6 2C3 H6O3 + 2 ATP (150 kJ)
Glucose Lactic acid Energy
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12.  Lactic acid accumulates in the muscles
causing muscular ache (cramp)
 An OXYGEN DEBT incurred because the
maximum rate of oxygen used is less than
the oxygen supplied
 Oxygen is pay off by rapid breathing
continues after the vigorous activity to
obtain sufficient oxygen
 The oxygen will break down the lactic acid
to carbon dioxide, water & energy
oxygen
Lactic acid carbon dioxide + water + energy
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13. ANAEROBIC RESPIRATION IN YEAST
 Yeast carries out both aerobic & anaerobic respiration
 Anaerobic respiration in yeast cells called
fermentation.
 Yeast secretes the enzyme zymase which hydrolyses
glucose in the absence of oxygen to form ethanol,
carbon dioxide & energy
C6H12O6 2C2H5OH + 2CO2 + 210 kJ
Glucose Ethanol carbon dioxide energy
 The enzyme zymase secreted by the yeast speeds up
the fermentation process
 The product of fermentation as CO2 is used as a raising
agent in aking bread while ethanol is used to produce
alcoholic drinks such as wine.
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14. COMPARISON BETWEEN AEROBIC
RESPIRATION & ANAEROBIC RESPIRATION
AEROBIC RESPIRATION ANAEROBIC
RESPIRATION
Presence of oxygen Absence of oxygen
Large amount of energy (38 Less energy (2 ATP @ 150
ATP @ 2898 kJ) kJ/210 kJ
Produce CO2 & water Produce lactic acid or ethanol
Completely broken down of Glucose not completely broken
glucose down
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