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Aerobic and Anaerobic
Respiration
Intermediate 2 Biology
Unit 1: Living Cells
Learning Objectives
Name the type of energy stored in food.
Describe the energy change when food is burned.
State the units used in measuring energy content of food.
Define the term respiration.
Name the food molecule that is the main source of energy in cells.
Energy Facts
Energy facts
Cannot be created or destroyed
Can be converted from one form to
another
Takes a variety of forms
Measured in kilojoules
Energy
Food is a store of chemical energy.
When food is burned, chemical energy
is converted into heat and light
energy.
Energy in Living Organisms
Work
Synthesis of complex substances
Active transport e.g. sodium-potassium pump
Movement
Bioluminescence
Maintenance of body temperature
Production of electricity
Maintenance, repair and division
Respiration
The chemical process by which energy
is released from cells is called
respiration.
The main source of energy for
respiration in cells is glucose.
This process is controlled by a series of
enzymes.
Progress questions
Fireflies can produce light in a process
called bioluminescence. Outline the
energy transformations that occur in
fireflies as they use energy from their
food to produce luminescence.
Comment on the statement below.
Respiration produces energy to form ATP.
Learning Objectives
Give the full name of ATP and draw a simplified diagram of its structure.
Name the molecule from which ATP is formed in cells and draw a simplified version of its structure.
Explain where the energy for the formation of ATP in cells comes from.
Explain what the energy from the breakdown of ATP is used for.
Structure of ATP
Adenosine triphosphate (ATP)
Adenosine
Three phosphate groups
Diagram of ATP
ATP
a high energy molecule
continually being hydrolysed and
resynthesised.
Formation and breakdown of
ATP
The combining of ADP + Pi to make ATP is an energy requiring process.
The breakdown of ATP to ADP + Pi is an energy releasing process.
The energy required for the formation of ATP from ADP + Pi comes from the respiration of glucose.
Transfer of chemical energy by ATP
Role of ATP
ATP is the energy source for: Muscle contraction
Cell division
Building up (synthesis) of proteins
Transmission of nerve impulses
If ATP is added to muscle tissue, it causes the muscle fibres to contract. The overall effect is that the muscle tissue shortens in length.
Think!!
Explain why ATP is known as the
universal energy currency.
Learning Objectives
Describe aerobic respiration (using the
words glucose, pyruvic acid, glycolysis,
carbon dioxide and water).
Chemistry of Respiration
Respiration is the process by which
chemical energy is released during the
breakdown of glucose
It occurs in every living cell
Involves the regeneration of ATP
Regeneration of ATP
A Pi Pi
Pi
Adenosine DiPhosphate (ADP)
+ Inorganic Phosphate (Pi)
A Pi Pi Pi
Adenosine TriPhosphate (ATP)
High
energy
bond
Takes in energy
Gives out energy
Glycolysis
Splitting of
glucose into
two molecules
of pyruvic acid
Results in the
production of
2ATP molecules
Glycolysis
C C C
C C C
1 Glucose
C C C
C C C
2 Pyruvic Acid
2 ADP + 2Pi 2 ATP
Aerobic breakdown of pyruvic
acid
Pyruvic acid is broken down in a series of enzyme controlled steps.
Each pathway leads to formation of Water
Carbon dioxide
18 molecules of ATP
As this takes place twice for each molecule of glucose the total gain of ATP is 36
Aerobic breakdown of pyruvic
acid
Investigating the activity of
enzymes in aerobic respiration
Investigating the activity of
enzymes in aerobic respiration During respiration, glucose is broken down,
hydrogen is released at various stages
This removal of hydrogen is controlled by an enzyme
Yeast contains stored food which can be used as a respiratory substrate
Resazurin dye changes colour when it gains hydrogen)
blue pink colourless
(no hydrogen) (lots of hydrogen)
Investigating the activity of enzymes in
aerobic respiration
Set up the three test tubes as shown
below. 10ml glucose
10ml yeast
5 ml dye
Investigating the activity of enzymes in
aerobic respiration
Shake tubes vigorously for 20 seconds, and place in a water bath set at 37oC.
Leave for a few minutes
Draw a diagram of your results
Can you explain your results.
Investigating the activity of
dehydrogenase enzyme in yeast
Tube A
Colour change from blue via pink to
colourless.
Hydrogen has been rapidly released and
has reduced the dye.
For this to happen enzymes present in
yeast cells must have acted on the
glucose, the respiratory substrate, and
oxidised it.
Investigating the activity of
dehydrogenase enzyme in yeast
Tube B Change from blue pink colourless
Reaction is slower since no glucose was added.
enzymes could only act on any small amount of respiratory substrate already present in the yeast cells.
Tube C Boiling has killed the yeast and denatured the
enzymes.
AEROBIC RESPIRATION
EXPERIMENTS
Energy content of food
Release of heat energy during
respiration
Respirometer do living things produce carbon dioxide?
Respirometer
Measuring the rate of respiration
Respirometer
A respirometer measures the rate of
respiration
Sodium hydroxide is a chemical that
absorbs carbon dioxide
Oxygen taken in by the animal causes
a decrease in volume in the enclosed
gas, the coloured liquid rises up the
tube.
Learning Objectives
Describe anaerobic respiration as the breakdown of glucose to pyruvic acid by glycolysis.
State that anaerobic respiration in animals is reversible and results in the production of lactic acid.
Describe the effect of lactic acid on muscle cells and subsequent repayment of the oxygen debt.
State that anaerobic respiration in plants is irreversible and results in the production of ethanol and carbon dioxide
Anaerobic Respiration
Partial breakdown of glucose in the
absence of oxygen
Glycolysis occurs as normal
2ATP are produced
Pyruvic acid then gets converted into
Lactic acid in animals
Carbon dioxide and ethanol in plants and
yeast (this is irreversible)
Anaerobic Respiration in
Animals
Anaerobic Respiration in animals
In muscles cells, lactic acid is formed during anaerobic respiration
A build up of lactic acid reduces the efficiency of muscles leading to muscle fatigue
Oxygen debt is the oxygen that needs to be repaid during
a rest period
Lactic acid is converted to pyruvic acid and respired aerobically
Anaerobic respiration in plants
and yeast
Anaerobic Respiration in plants
and yeast
When oxygen is absent plants and
yeast respire anaerobically
Carbon dioxide is lost from each molecule
of pyruvic acid
Ethanol is formed
This is irreversible
Learning Objectives
Describe an experiment, including a
labelled diagram of the apparatus, to
investigate anaerobic respiration in
yeast and say what happens.
Comparing aerobic and
anaerobic respiration
Aerobic
respiration
Anaerobic
respiration
Need for
oxygen
Energy yield
Degree of
breakdown of
glucose
End products
Comparing aerobic and
anaerobic respiration
Aerobic
respiration
Anaerobic
respiration
Need for
oxygen
Oxygen
required
Oxygen
absent
Energy yield 38 ATP 2 ATP
Degree of
breakdown of
glucose
complete partial
End products Carbon dioxide and water
Animals lactic acid
Plants ethanol and
CO2
