Download B2.4 - The John Warner School

Learning objectives
Students should learn:
 that during aerobic
respiration, glucose and
oxygen are used to release
energy
 how carbon dioxide and
water are released as waste
products
 that most of the reactions in
aerobic respiration occur
inside mitochondria.
Course
Subject
Topic
Pages
Additional
science
Biology
B2 4.1 Aerobic respiration
Pages 46–47
Learning outcomes
Specification link-up
Kerboodle
Most students should be
able to:
The chemical reactions inside cells are controlled by enzymes.
[B2.6.1 a)]
During aerobic respiration (respiration that uses oxygen) chemical
reactions occur that:
 use glucose (a sugar) and oxygen
 release energy. [B2.6.1 b)]
Aerobic respiration takes place continuously in both plants and
animals. [B2.6.1 c)]
Most of the reactions in aerobic respiration take place inside
mitochondria. [B2.6.1 d)]
Aerobic respiration is summarised by the equation:
glucose + oxygen → carbon dioxide + water (+ energy) [B2.6.1 e)]
Energy that is released during respiration is used by the organism.
The energy may be used:
 to build larger molecules from smaller ones
 in animals, to enable muscles to contract
 in mammals and birds, to maintain a steady body temperature in
colder surroundings
 in plants, to build up sugars, nitrates and other nutrients into
amino acids which are then built up into proteins. [B2.6.1 f)]
Controlled Assessment: AS4.3 Collect primary and secondary data
[AS4.3.2 a)]; AS4.5 Analyse and interpret primary and secondary
data. [AS4.5.2 a)], [AS4.5.4 a)]
Chapter map:
Energy from
respiration
 describe the raw materials
and products of the
process of respiration
 describe where the
reactions take place in
cells
 explain why more active
cells, such as muscle
cells, have greater
numbers of mitochondria
than less active cells.
Some students should also
be able to:
 design experiments
independently to show
that oxygen is taken up
and carbon dioxide is
released during aerobic
respiration.
Teacher notes:
Energy from
respiration
Lesson structure
Support, Extend and Practical notes
Starters
Turning limewater cloudy – Draw crosses on the bottoms of test
tubes with a chinagaph pencil. Half-fill each tube with limewater. Give
each student a drinking straw (use bendy straws) and a tube of
limewater and tell them to blow gently through the straw into the
limewater until they can no longer see the cross on the bottom from the
top. Eye protection must be worn. Ask: ‘How long does it take? What is
happening?’ Go over the reaction and introduce respiration. (5 minutes)
Instant energy – Show glucose drink bottles, energy drinks and
energy bars. Read or show their labels and read as a class (search an
image bank for ‘energy drink label’). Support students by giving them
pre-printed lists of sugar content and energy and ask to put the
products in order of their highest sugar and energy content to the
lowest. Extend students by asking them to study the contents and
decide which would supply the most energy and which would supply
energy the fastest, giving reasons. (10 minutes)
Main
Provide a short, introductory PowerPoint presentation or exposition on
the need for energy and the process of aerobic respiration. Build up the
word equation, getting students to work out what the raw materials and
the products are. Introduce mitochondria and show a diagram and
electron micrograph images of mitochondria in cells. Provide the
students with a worksheet containing an outline of a mitochondrion
which they can complete.
As a follow-up to the starter ‘Turning limewater cloudy’, a more refined piece
of apparatus can be used to show that the air that is breathed in contains
less carbon dioxide than air breathed out (see ‘Practical support’).
Investigating respiration using a small mammal or plant (see ‘Practical
support’). All these experiments need controls, which should be
discussed with the students (this relates to ‘How Science Works’–
validity of experimental design). In most cases, with the bell jar
experiments, the removal of the living organism should be considered
as a control.
Plenaries
How small can you get it? – Have a competition to see who can fold an A4
sheet of paper into the smallest volume. Ask: ‘What is the best method?’
Relate to surface area (SA) and cristae in mitochondria. (5 minutes)
What do I need energy for? – Ask students to write down as many uses for
the energy released by respiration that they can think of. Build up a list on the
board. Support students by providing prompts once they have completed
their initial list. Extend students by ensuring their lists include references to
cell activities and animals other than humans. (10 minutes)
Support
Get students to make model mitochondria from date boxes or washing liquid capsule
boxes. They should line them with corrugated cardboard to represent the inner
membrane. Fill with used batteries to indicate their role as energy carriers and
display on a large poster.
Give them cards with the components of the word equation for aerobic respiration
and get them to assemble the equation.
Extend
Give students a sheet on the theories of Alan Templeton and Rebecca Cann with
regard to ‘Mitochondrial Eve’ and the origins of the human species. Ask them to
summarise points for and against each theory.
Practical support
Composition of inhaled and exhaled air
Equipment and materials required
Test tubes half-full of limewater in racks, test tubes with 2-hole bungs, delivery tubes
(one long, one short), rubber tubing, sterile mouth pieces, chinagraph pencil, drinking
straws (bendy ones if possible or tubing and clips, eye protection.
Details
Arrange two tubes of limewater, tubing and clips, so that air can be drawn in through
one tube containing limewater and breathed out through another tube containing
limewater. After a few breaths, it can clearly be seen that the limewater in the two
tubes differs in cloudiness.
Investigating respiration using a small mammal or plant
Equipment and materials required
Limewater, soda lime in U-tube, small mammals in a bell jar, potted plant,
earthworms, maggots or woodlice, black paper, tubing, air pump, 2 boiling tubes,
bungs, delivery tubes, boiling tube rack, eye protection.
Details
A small mammal, or other small living animals, can be placed under a bell jar on a glass
plate sealed with Vaseline. Emphasise to the students that the animal has fresh air drawn
across it all the time, just with the carbon dioxide removed. Air is drawn through the
apparatus, first passing through a U-tube of soda lime (to remove carbon dioxide and then
through a tube of limewater (to show that carbon dioxide has been removed before entering
the bell jar). After leaving the bell jar, the air is drawn through another tube of limewater to
show that carbon dioxide is given off. Any small mammal is usually quite active and a result
is achieved fairly quickly. Alternatively, other small animals, such as earthworms, woodlice
or maggots can be used in such a demonstration/investigation. It is possible to substitute a
potted plant for the small mammal and to show that carbon dioxide is given off during
respiration in plants. The pot and soil of the plant need to be enclosed in a polythene bag
and the bell jar needs to be covered in black paper to exclude light. The apparatus should
be left running for a couple of days. Ask: ‘Why is the plant pot covered up? Why is light
excluded?’
Safety: CLEAPSS Hazcard 18 Limewater – irritant. CLEAPSS Hazcard 91 Soda
lime – corrosive.
Text © Ruth Miller, Geoff Carr, Darren Forbes, Sam Holyman 2011
Course
Subject
Topic
Pages
Additional
science
Biology
B2 4.2 The effect of exercise
on the body
Pages 48–49
Learning objectives
Learning outcomes
Specification link-up
Kerboodle
Students should learn:
 that muscles need energy
from respiration in order to
contract
 that, during exercise, there
is an increase in the blood
flow to the muscles so
more glucose and oxygen
is supplied and carbon
dioxide removed
 that glycogen provides a
store of energy in the
muscles.
Most students should be
able to:
 describe how the body
responds to the demands
of exercise
 describe how glycogen is
used in the body.
Some students should also
be able to:
 interpret data on the use
of oxygen/ heart rate
increase during exercise.
 relate the responses of the
body to exercise and the
ability of the muscles to
contract efficiently.
Energy that is released during respiration is used by the
organism. The energy may be used:
 to build larger molecules from smaller ones
 in animals, to enable muscles to contract
 in mammals and birds, to maintain a steady body
temperature in colder surroundings
 in plants, to build up sugars, nitrates and other nutrients
into amino acids which are then built up into proteins.
[B2.6.1 f)]
During exercise a number of changes take place:
 the heart rate increases
 the rate and depth of breathing increases
 the arteries supplying the muscles dilate. [B2.6.1 g)]
These changes increase the blood flow to the muscles and
so increase the supply of sugar and oxygen and increase the
rate of removal of carbon dioxide. [B2.6.1 h)]
Muscles store glucose as glycogen, which can then be
converted back to glucose for use during exercise. [B2.6.1 i)]
Interpret the data relating to the effects of exercise on the
human body. [B2.6]
Controlled Assessment: AS4.1 Plan practical ways to
develop and test candidates’ own scientific ideas [AS4.1.1 a)
b, c)]; AS4.3 Collect primary and secondary data [AS4.3.2 a)
b)]; AS4.4 Select and process primary and secondary data
[AS4.4.1 a) b)], [AS4.4.2 a) b) c)]; AS4.5 Analyse and
interpret primary and secondary data. [AS4.5.4 a) c) d)]
Video: Exercise
Support:
Respiration
How Science
Works: The
effect of exercise
on the body
Bump up your
grade: Glucoseenriched drinks
Practical:
Measuring pulse
rate before and
after exercise
Lesson structure
Support, Extend and Practical notes
Starters
Cardiac muscle contraction – Show an MPEG file or a video clip of contracting heart
muscle. Discuss what the energy source for this movement will be and the reaction
involved. Support students by prompting and extend students by asking how the energy
source gets to the muscle and what happens to the waste products. (5 minutes)
Exercise … how much do you get? – Show a clip from an old exercise video such
as Mr Motivator, with some good 1980s clothes to have a laugh at. Also, show some
footage of modern gym clubs. Carry out a quick survey to find out the health and
exercise activities of the class members and their families. (10 minutes)
Main
Investigate the effect of exercise on heart rate (see ‘Practical support’). There are
many variations on this investigation that can be carried out:
 the intensity of the exercise can be varied
 the increase in breathing rate (number of breaths per minutes) can be
investigated either separately from the pulse rate or in conjunction with it
 in addition to the performance of individuals, comparisons could be made
between members of the class who exercise regularly and those who do not.
This investigation can be used for teaching/assessing ‘How Science Works’:
hypotheses can be formulated and predictions made, measurements taken and
results tabulated, graphs produced and conclusions drawn, finishing with an
evaluation. This can deliver the complete range of investigative requirements from
which to choose a skill or skills to develop.
Digital pulse monitors can be used and it is possible to use data loggers and get live
read-out graphs that can be displayed through a projector.
Plenaries
Animal starch – Glycogen has been referred to as ‘animal starch’. Ask students to
compile two lists: one headed ‘similarities to starch’ and the other headed
‘differences from starch’. Stress that it is not starch and that animals do not store
starch. Support students by giving them a number of straightforward statements
about the two molecules which they have to sort into the correct list. Extend students
by encouraging them to include differences in structure, location and use. They could
continue the task for homework. (5 minutes)
‘Unfit’ club – Imagine an ‘Unfit’ club, where the membership rules included the
banning of exercise. Write down instructions for the club’s Unfitness Enforcers,
giving a list of telltale signs that would indicate the person being investigated has
been exercising. Use imagination and illustration, being careful regarding the size
sensitivity of some students. (10 minutes)
Support
Create and use jigsaw sheets of the human body and the
changes which happen due to exercise. Blank jigsaw sheets
can be bought or you can make your own. Support students
by offering clues if necessary.
Extend
Tell students that a young woman has been found dead in a
field. No one knows her identity. Students could write a letter
of advice from a pathologist telling the police what they can
find out about her exercise habits and lifestyle from her
corpse, to aid with her identification.
Get them to calculate the percentage changes in the
parameters measured in the table in the Student Book and to
comment on the significance of these changes.
Practical support
Testing fitness
Equipment and materials required
The practical activities suggested in this spread do not require
complex apparatus. The pulse and breathing rate investigations
simply require stopwatches or stop-clocks. If a spirometer is used,
then follow the instructions supplied with it.
Details
This is best carried out in pairs, so that students can record
each other’s pulse rates. Before starting, the students should
decide on the level and period of exercise. The simplest
investigation could concentrate on one level of exercise, such
as walking on the spot for a set time. The resting pulse rate in
beats per minute should be determined (count beats in 15
seconds and then multiply by 4). Show the students how to
do this either using the radial artery on their wrists, using the
carotid artery in the neck or a pulse rate monitor. Ideally, this
should be done three times and a mean taken. The student
then undertakes the exercise and the pulse rate recorded
immediately and at set intervals, such as every minute
afterwards, until the rate returns to normal. A graph can be
plotted of heart/pulse rate against time. The students
exchange roles.
Safety: Students should exercise sensibly.
Text © Ruth Miller, Geoff Carr, Darren Forbes, Sam Holyman 2011
Course
Subject
Topic
Pages
Additional science
Biology
B2 4.3 Anaerobic respiration
Pages 50–53
Learning objectives
Learning outcomes
Specification link-up
Kerboodle
Students should learn:
 that during long periods of
vigorous activity, muscles
respire anaerobically in
order to obtain energy
 that less energy is
released by anaerobic
respiration than aerobic
respiration
[HT only]
 that during anaerobic
respiration, incomplete
breakdown of glucose
results in the formation of
lactic acid and the building
up of an oxygen debt.
[HT only]
Most students should be
able to:
 explain why muscles
respire anaerobically
during vigorous exercise
 explain why less energy is
released by anaerobic
respiration [HT only]
 describe the oxygen debt
and how it is repaid.
[HT only]
Some students should also
be able to:
 interpret data relating to
the effects of exercise on
the human body [HT only]
 explain the principle of
oxygen debt and why
speed of recovery from
exercise is a measure of
physical fitness. [HT only]
During exercise, if insufficient oxygen is reaching the
muscles, they use anaerobic respiration to obtain
energy. [B2.6.2 a)]
Anaerobic respiration is the incomplete breakdown of
glucose and produces lactic acid. [B2.6.2 b)]
As the breakdown of glucose is incomplete, much less
energy is released than during aerobic respiration.
Anaerobic respiration results in an oxygen debt that has
to be repaid in order to oxidise lactic acid to carbon
dioxide and water. [B2.6.2 c)] [HT only]
If muscles are subjected to long periods of vigorous activity,
they become fatigued, i.e. they stop contracting efficiently.
One cause of muscle fatigue is the build up of lactic acid in
the muscles. Blood flowing through the muscles removes the
lactic acid. [B2.6.2 d)]
Controlled Assessment: AS4.1 Plan practical ways to
develop and test candidates’
own scientific ideas [SA4.1.1 a) b) c)]; AS4.3 Collect
primary and secondary data
[AS4.3.2 a) b)]; AS4.4 Select and process primary and
secondary data. [AS4.4.1 a) b)], [AS4.4.2 a) b) c)]
How Science Works:
How quickly do
muscles fatigue?
Extension: The
cyanide deadline
Interactive activity:
Energy from
respiration
Podcast: Energy
from respiration
Test yourself: Energy
from respiration
On your marks:
Energy from
respiration
Examination-style
questions: Energy
from respiration
Answers to
examination-style
questions: Energy
from respiration
Lesson structure
Support, Extend and Practical notes
Starters
Wile E. Coyote and Road Runner – Show the students a video clip of Wile E. Coyote and
Road Runner at the start of the episode ‘Lickety Splat’ – the first minute or so where Wile E.
runs very hard and gets out of breath. This can be found on the internet. Draw out a thumbnail
sketch of the graph you would expect of his breathing rate against time, labelling what is
happening in each section. (5 minutes)
Sprinting! – Show a video of a 100 m sprint (from the Olympics or the World Championships),
where the athletes are shown immediately before and afterwards. Get students to observe the
behaviour of the athletes. Comment on breathing, whether they collapse, etc. Support students
by asking questions such as: ‘Are they breathing deeply? Can they talk?’ Extend students by
getting them to make their observations without prompting and expecting more detailed
comments and reasons. (10 minutes)
Main
Take the opportunity of clearing up the mistaken idea that it is lactic acid building up in muscles which
makes them sore – this is not so! Lactate is actually used as a fuel by the mitochondria and makes no
contribution to soreness/stiffness afterwards. Explain to extension level students that the actual reason
for the acidification during exercise is the build up of H+ ions which are released during the break down
of ATP to ADP + Pi. They are produced so fast, they overcome the body’s buffering mechanism and
cause painful burning sensations.
Practical on making lactic acid (see ‘Practical support’ for full details).
There are variations on this investigation that can be discussed and students could be asked to
design a standard test that everyone could do, and this could be used to determine whether
muscle fatigue varied from person to person. For example, the same action could be carried
out for a set time and a set recovery time allowed. Students could find out if they could
continue longer doing that, rather than carrying out the investigation as first suggested.
If the variation in breathing rate with activity was not used in the previous spread, it could be
investigated here. (This relates to ‘How Science Works’.) Again, it would be sensible for students to
work in pairs, so that the record keeping is done by the partner, and then the roles can be reversed. In
this case, it could be appropriate to vary the intensity of the exercise, starting with walking on the spot,
then running on the spot and so on. Carry out the exercise for a set time and record breathing rates
until they return to normal, before starting on a more vigorous exercise.
Plenaries
The long distance runner – Show video footage of a long-distance race, at the beginning,
during and at the end. Students to observe the behaviour of the athletes and compare with the
sprint shown as a starter. Ask: ‘Do the athletes seem so out of breath? Or are they breathing
as deeply?’ Discuss why there are differences in behaviour. (5 minutes)
Energy yields – Anaerobic respiration in yeast cells produces alcohol. Show students that
there is energy locked up in alcohol by igniting some in controlled conditions (could use it in a
spirit lamp or similar). Link to the energy still in lactic acid. Get students to compare the energy
yields of aerobic and anaerobic respiration. Support students by giving them the figures which
they could represent in a simple way. Extend students by comparing the structures of glucose,
lactic acid, alcohol and carbon dioxide, in terms of the numbers of C, H and O atoms in the
molecules. (10 minutes)
Support
Make cards with the relevant words and symbols
for students to compose equations for aerobic and
anaerobic respiration.
Extend
Ask students to research the differences between
the different energy systems used by muscles. Get
them to find out the differences in the training
programmes of sprinters and marathon runners.
Practical support
Making lactic acid
Equipment and materials required
Stopwatches, stop-clocks or a spirometer.
Details
Students should work in pairs and devise a simple
repetitive action, such as stepping up and down on
to a low bench, lifting a book from the bench to
shoulder height or raising one arm and clenching
and unclenching the fist twice a second. One
student should perform the action as many times
as they can before tiring, while the other student
keeps a record of the number of actions and the
time. A period of recovery time is allowed – the
student to decide when they are ready to resume
the activity, but record the time. Ask: ‘Can they do
the same number of actions before tiring again?
Are they performing the action at the same speed
as before? Why does the student slow down?’
Safety: No student should feel under pressure to
take part in any of the activities, particularly if they
have any medical condition. If a spirometer is used,
follow the instructions given in CLEAPSS
Handbook CD-ROM section 14.5.
Text © Ruth Miller, Geoff Carr, Darren Forbes, Sam Holyman 2011