This is my original work

1. CONTD.

2. ANAEROBIC RESPIRATION IN ANIMALS AND
PLANTS
 Anaerobic respiration is the process by which food
substances are broken down in absence of oxygen.
 Takes place in cytoplasm.
 Unlike in aerobic respiration glucose is not completely
broken down to release carbon (IV) oxide, water and
energy.
 Incomplete breakdown of glucose lead to production
of less energy compared to aerobic respiration.
 End products include carbon (IV) oxide, energy and
either alcohol (in plants) or lactic acid (in animals).

3. Summary of the process
(chemical and word equations)
 In plants
 C6H12O6 2C2H5OH + 2CO2 + Energy (ATP)
Glucose Alcohol + Carbon (IV) + Energy
(ethanol) Oxide
 In animals
 C6H12O6 2C3H6O3 + Energy (ATP)
Glucose Lactic acid + Energy

4. Fate of the products
 The products such as carbon (IV) oxide, alcohol and
lactic are toxic if allowed to accumulate. They must be
eliminated immediately they are formed.
 Energy produced is used to drive life processes.
N.B: The anaerobic respiration leading to production of
alcohol is called fermentation.
 It occurs in when bacteria or yeast break down simple
sugars. Similarly some bacteria break down alcohol
into ethanoic acid in the same process while milk is
broken into lactic acid.

5. Anaerobic respiration in human
 Occurs during a strenuous exercise.
 Causes production of lactic acid which accumulates in
muscles. It is toxic and causes muscle crumps.
 It is transported to the liver by blood. Here, it is
oxidized to carbon (IV) oxide and water by enzyme
lactic dehydrogenase.
 Extra oxygen needed to break down lactic acid is called
oxygen debt.
 It is taken up during panting after the exercise.

6. FERMENTATION

7. The process is also known as alcoholic
fermentation or anaerobic respiration.
 The calcium hydroxide forms white precipitate as a result
reacting with carbon (IV) oxide. This is calcium carbonate.
 Carbon (IV) oxide is produced when yeast breaks down
glucose in absence of oxygen.
 During this process, effervescence (bubbles) is observed in
tube with glucose and yeast . This is due to production of a
gas i.e. carbon (IV) oxide during respiration.
 Yeast has this kind of respiration (word equation).
Glucose yeast Alcohol + Carbon (IV) + Energy
(ethanol) Oxide

8. Activity
 Suggest the optimum temperature under which the
reaction takes place.
 Explain what would happen if the experiment was
done under the following conditions. Give reasons for
you answers.
(i)Done at 1000c temperature.
(ii) Done at 50c temperature.

9. APPLICATION/IMPORTANCE OF ANAEROBIC
RESPIRATION.
 Useful in alcohol production e.g. wine making (from
fruits and stems) and beer making (from germinating
seeds).
 Applied in baking industry – yeast in dough make it
rise due to production of carbon (IV) oxide.
 It is also useful in processing of dairy products – milk
fermentation, cheese production, yoghurt making and
commercial acids such as vinegar and citric acid.
 Production of biogas is a function of fermentation
 Important in sewage treatment.

10. ‘OXYGEN DEBT’
 Refers to oxygen required to get rid of lactic acid
accumulated in the body tissues when they respire in
limited oxygen (anaerobically).
 Lactic acid might cause fatigue and result in muscle
crumps.
 Oxygen debt incurred is paid back quick and deep
breathing so as to increase oxygen supply during
recovery period e.g. panting.
 During recovery period, lactic acid is oxidized to
carbon (IV) oxide, water and energy (in presence of
oxygen), or taken to liver and converted to glycogen.

11. COMPARISON BETWEEN AEROBIC AND
ANAEROBIC RESPIRATION
AEROBIC ANAEROBIC
 Oxygen is necessary for it to
take place hence substrate
broken down completely.
 Substrate broken down
completely to carbon (IV)
oxide and water.
 Water molecules are
produced.
 Oxygen is not required
hence the substrate not
broken down completely.
 Substrate not broken down
completely resulting to
production of alcohol or
lactic acid.
 Water molecules are not
produced.

12. COMPARISON CONTINUED
AEROBIC ANAEROBIC
 End products (carbon (IV)
oxide) and water easily diffuse
before they accumulate in
body.
 Energy is released slowly over
short periods of time.
 More efficient as high
amounts of energy are
released. 2880KJ/MOLECULE
of sugar (38 ATP molecules)
 End products (alcohol and
lactic acid) are toxic to cells
and quickly accumulate in
body.
 Energy released faster over
short periods of time.
 Less efficient as low amounts
of energy are released.
210KJ/MOLECULE of sugar,
(2 ATP molecules)