Brown's Biology AQA GCSE Additional Science-BIOLOGY 2
B2.6 Aerobic and anaerobic respiration
for GCSE Additional Science or GCSE Biology
REVISION NOTES GUIDE SUMMARY: What do you need to know
for the examinations? What do you need to able to do in the exams? In AQA GCSE Science
A examinations HT means for higher tier students only.
Sorry, but I don't have much time to answer questions, but if you see any
apparent errors or wish to comment, please
email me. All my notes, learning
objectives, comments for exam revision are based on the official AQA GCSE Science A Key Stage 4
AQA GCSE Science BIOLOGY 2 Unit
B2.6 Aerobic and anaerobic respiration
Know and understand that respiration in cells can take place aerobically or anaerobically.
Know and understand that the energy
released in respiration is used in a variety of ways.
Know that the human body needs to react to the increased demand for energy during
You should be able to use your
skills, knowledge and understanding to interpret the data relating to the effects of exercise
on the human body.
AQA GCSE Science BIOLOGY Unit B2.6.1 Aerobic respiration
a) Know and understand the chemical reactions inside
cells are controlled by enzymes.
b) Know and understand during aerobic respiration
(respiration that uses oxygen) chemical reactions occur that:
c) Know and understand that aerobic respiration
takes place continuously in both plants and animals.
d) Know that most of the reactions in
aerobic respiration take place inside the mitochondria of cells.
e) Know that aerobic respiration
is summarised by the equation:
f) Know and understand that energy that is released
during respiration is used by the organism.
g) Know and understand that during exercise a number of
changes take place in your body:
the more you use your muscles,
the more oxygen you need for respiration
the heart rate increases, the
more so, the more vigorous the exercise, and even more oxygen and glucose
the rate and depth of
breathing increases, to increase oxygen intake.
h) Know and understand that these changes increase
the blood flow to the muscles and so increase the supply of sugar and oxygen
for energy from respiration and also increase the rate of removal of carbon dioxide
- the waste product.
i) Know and understand that muscles store glucose
as glycogen, which can then be converted back to glucose for use during
Glycogen is produced, stored and
then released for conversion to glucose on a supply and demand basis.
If there is surplus glucose and
physical activity is low, more glycogen is produced.
The more you physically
exercise, the greater the glucose demand, if this exceeds what is available
in the blood stream, then the glycogen reserves are called upon to fill the
AQA GCSE Science BIOLOGY Unit B2.6.2 Anaerobic respiration
a) Know and understand during exercise, if
insufficient oxygen is reaching the muscles they use anaerobic respiration
to obtain energy.
b) Know and understand anaerobic respiration
is the incomplete breakdown of glucose and produces lactic acid.
glucose ==> lactic acid +
This is not as efficient in
energy release as the complete aerobic respiration of glucose described in
the previous section, but it does enable you to keep your muscles going for
Anaerobic respiration produces a
build up of lactic acid in the muscles which can be painful e.g. you suffer
However, anaerobic respiration
has the advantage of enabling the body to keep going for a limited time,
even if your a bit short of oxygen!
c) HT only: Know and
understand that as the breakdown of glucose
is incomplete, much less energy is released than during aerobic respiration.
HT only: Know and
understand anaerobic respiration results in an oxygen debt that has to be repaid in
order to oxidise lactic acid to carbon dioxide and water.
The heart, lungs and limb
muscles begin struggle to keep up with what you want your body to do
you can keep your muscles going longer using anaerobic respiration, at least up to a point
of total fatigue (like just about staggering over the line at the end of a
However, even when you stop
doing a vigorous exercise, you continue to breathe quite deeply to repay
this oxygen debt and oxidise the lactic acid to the harmless waste products
of carbon dioxide and water.
As long as your body detects
higher than normal levels of carbon dioxide or lactic acid your breathing
rate and pulse rate will stay higher than normal until their levels are
reduced to normal, i.e. when all the excess lactic acid has been oxidised to
carbon dioxide and water.
d) Know and understand
that if muscles are subjected to
long periods of vigorous activity they become fatigued, ie they stop
Know that one cause of muscle fatigue is the build-up of
lactic acid in the muscles.
Know that blood flowing through the muscles removes the
lactic acid and oxygen is used up to oxidise it to carbon dioxide and water.
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