Course
Subject
Topic
Pages
Biology
Biology
B3 1.1 Osmosis
Pages 214-215
Learning objectives
Learning outcomes
Specification link-up
Kerboodle
Students should learn:
 that water often moves
across boundaries by
osmosis and why it is
important
 that osmosis is the diffusion
of water through a partiallypermeable membrane from
a dilute to a more
concentrated solution
 that differences in
concentrations of solutes
inside and outside cells
cause water to move by
osmosis.
Most students should be able to:
 define osmosis
 distinguish between diffusion and
osmosis
 carry out an experiment to find
out about the process of osmosis
 explain the results of
experiments in terms of osmotic
movement of water.
Some students should also be
able to:
 explain the importance of
osmosis in plants and animals.
Dissolved substances move by diffusion and by
active transport. [B3.1.1 a)]
Water often moves across boundaries by
osmosis. Osmosis is the diffusion of water from
a dilute to a more concentrated solution through
a partially permeable membrane that allows the
passage of water molecules. [B3.1.1 b)]
Differences in the concentrations of the
solutions inside and outside a cell cause water
to move into or out of the cell by osmosis.
[B3.1.1 c)]
Controlled Assessment: B4.5 Analyse and
interpret primary and secondary data. [B4.5.4 a)]
Chapter map: Exchange
of materials
Data handling skills:
Osmosis in potatoes
Practical: Investigating
osmosis in beetroot
How science works:
Investigating osmosis in
beetroot
Support: Which way
does the flow go?
Bump up your grade:
Which way does the
flow go?
Lesson structure
Support, Extend and Practical notes
Starters
Bouncy Castle – Show a picture of a Bouncy Castle. Has anyone got younger
brothers or sisters who love these? How do they stay upright? Why don’t they
burst? What would happen if they were made out of elastic rubber like a thicker
version of balloons? Draw out the idea of a balance of air going in, air coming out
and pressure on a non-elastic skin providing support. Link with osmosis in plants
providing support for plant tissues. (5 minutes)
What happens to the chips – Show the students a bag of chips. Ask who is going
to the chip shop tonight. At what time? Explain that there is always a rush on at
about six o’clock, so the owners prepare the chips in advance and keep them in
water. Ask, ‘What effect does the water have on the chips?’ Support students by
giving them some suggestions from which to choose. Draw out some ideas from
the class. Extend students by asking them to suggest ways of testing these ideas.
(10 minutes)
Main
 Modelling osmosis in cells (see ‘Practical support’). The results from the model
cells can be used to illustrate the principles of osmosis. Ask students to
interpret each one in terms of the diffusion of water and sucrose molecules and
the effect of the partially-permeable membrane. Students may find it easier to
understand osmosis if it is explained in terms of the diffusion of water
molecules from where they are in high concentration (i.e. in a dilute solution) to
where there is a lower concentration (i.e. a more concentrated solution).
Diagrams help.
 Investigating osmosis in potato tissue (see ‘Practical support’).
 There are variations on the above which can be tried. Some students could
measure changes in dimensions (i.e. length or volume) and others could
measure changes in mass. Are the results similar? Which do they consider to
be the most accurate?
 Setting up an osmometer – A simple osmometer can be made using a length of
Visking tubing, tied securely at one end, filled with a concentrated sugar solution.
(For quick results use syrup or treacle only slightly diluted) and then a capillary tube
tied securely in the top. The whole apparatus is held in place by a clamp and stand
and lowered into a beaker of water. The level of sucrose in the capillary tube is
measured at the start and then again at regular intervals (5 minutes). A graph can be
plotted of the distance moved by the sucrose against time.
Plenaries
Follow up to ‘What happens to the chips?’ – If the demonstrations were set up at the
beginning of the experiment, they can be looked at. What has happened to the chips?
They can be measured, their texture assessed and the results discussed. Support
students by asking them whether their chosen suggestions were correct. Students can
be extended by asking them to calculate percentage change in dimensions. (5 minutes)
Bank account osmosis – who is most in the red? – Select three students. Tell one
they are overdrawn by £10. Tell another they are overdrawn by £20 and the third by £30.
Give them each 2p. Tell them that they have to give it to anyone who has less money
than they have (i.e. is more overdrawn than them). The money should go from the £10
overdrawn to the £20 overdrawn and finish up with the £30 overdrawn. Explain that it is
the same with osmosis. The coins represent water, which always goes to the most
negative of any pair of cells in contact. (10 minutes)
Support
Carry out a stop motion of a plant wilting and being re-hydrated
using Intel play microscopes (the kit pot plastic ones). Explain
using a football and a pump.
Extend
Get students to investigate the effect of partial drowning. What
effect would it have on the water balance in the body?
Practical support
Investigating osmosis
Equipment and materials required
Lengths of dialysis (Visking) tubing for each group of students,
Molar sucrose solution which can be diluted to the
concentrations required, beakers, string, small measuring
cylinders or pipettes to fill the tubes, glass tubes.
Details
Use the dialysis (Visking) tubing to make model cells. Lengths
of tubing, about 10 cm long, should be wetted thoroughly and
one end of each tied firmly with string. Fill the tubing bags with
a concentrated sugar solution (molar sucrose) and tie the open
ends firmly with string. These Visking tubing bags represent
cells and can be immersed in beakers of water, less
concentrated and more concentrated sugar solutions.
Investigating osmosis in potato tissue
Equipment and materials required
Fairly large potatoes, cork borers to make cylinders of tissue,
knives and tiles to cut chips, molar sucrose, boiling tubes and
racks, rulers and balances, tissues or paper towels to dry
potato discs or slices.
Details
Chips or discs of potato tissue can be immersed in different
concentrations of salt or sugar solutions, left for a period of time
and then their change in mass or dimensions measured. Such
experiments offer opportunities for the introduction of ‘How
Science Works’ concepts and can be used as whole
investigations. The change in mass or length can be plotted
against the concentration of the solution and the solution which
results in the least change is considered to be equivalent to the
concentration of the cell sap of the potato.
Safety: Take care with sharp implements.
New AQA GCSE Science © Nelson Thornes Ltd 2011
Course
Subject
Topic
Pages
Biology
Biology
B3 1.2 Active transport
Pages 216-217
Learning objectives
Learning outcomes
Specification link-up
Kerboodle
Students should learn:
 that active transport is the
absorption of substances against a
concentration gradient
 that energy from respiration is
needed to carry out active
transport
 that active transport enables cells
to take up ions from very dilute
solutions
 that sugars and ions can pass
through cell membranes.
Most students should be able to:
 describe how active transport
occurs
 state examples of active transport
in plants and animals
 explain the importance of active
transport to plants and animals.
Some students should also be able
to:
 explain in detail how active
transport across a cell membrane
takes place.
Substances are sometimes absorbed
against a concentration gradient. This
requires the use of energy from
respiration. The process is called active
transport. Active transport enables cells
to absorb ions from very dilute solutions.
[B3.1.1 g)]
Animation: Active
transport
Lesson structure
Support, Extend and Practical notes
Starters
‘Hungry hippos’ game – Remind students of this game, where they have
to grab marbles from a central arena using hippo-shaped scoops. The
marbles caught end up in the traps. Use this as an analogy to describe taking
molecules from an area of low concentration to an area of high concentration.
(5 minutes)
Quick quiz – Give the students ten short questions on slips of paper, on
osmosis and diffusion to recap work done so far. Support students by
supplying them with the answers and getting them to match the answer
to the correct question. Extend students by giving them the answers and
getting them to write the questions. (10 minutes)
Main
 If easily available, show some animations on active transport. Note: It
is very difficult to explain how active transport works without referring
to carrier proteins and pumps in the membranes.
 Prepare a PowerPoint presentation on the need for certain mineral
ions for healthy growth, (nitrate, magnesium and phosphate) the
presence of these ions in the soil solution and the cell sap, and the
way that plants accumulate ions against the concentration gradient.
 A useful example of the need for energy in respiration is to describe a
hydroponics system, where solutions are aerated to provide oxygen
for the respiration of the roots.
 Show photographs of marine vertebrates and discuss the problems
of the salt in their diets and how they get rid of it. There is some
information on the internet, especially from the RSPB web site.
www.rspb.org.uk
 To get across the idea of energy being needed, use a revolving door
analogy. If something valuable is on the far side (students to decide
what it is!), then it is worthwhile keeping on giving the door a good
hard shove, even if you have got plenty inside already.
Plenaries
‘Where in the body? – Give the students a blank body diagram each and get
them to draw on where active transport will take place. Support students by
providing them with strips of paper or labels with the names of body parts on
them. Get them to place the labels for body parts where active transport takes
place on to their blank diagrams. Extend students by getting them to explain
why active transport occurs and what is being actively transported. Annotate
with reasons. Examine in pairs. (10 minutes)
Support
Use a short piece of hose-pipe with a perforated section where it passes
a large card labelled ‘kidney’. Pour a mixture of salt and sugar into the
tube. Catch the salt and sugar as it comes out and put it back into
another hole in the hose pipe that comes after the perforations. Explain
that we need to reabsorb some substances even when there are more of
them on the inside than on the outside and that this takes energy.
Extend
Get students to do internet research on the number of ATP molecules
produced during respiration of a glucose molecule. Relate this to the
energy required to take in a molecule of glucose by active transport. If
needed, set up a ‘Scavenger Hunt’ style series of URLs with the data
needed on them.
New AQA GCSE Science © Nelson Thornes Ltd 2011
Course
Subject
Topic
Pages
Biology
Biology
B3 1.3 The sports drink
dilemma
Pages 218-219
Learning objectives
Learning outcomes
Specification link-up
Kerboodle
Students should learn:
 that sweat containing water and
mineral ions is lost during exercise
and can affect the concentration of
the body fluids
 that water and mineral ions need to
be replaced to avoid dehydration
 that sports drinks are claimed by the
manufacturers to help the body
replace used energy and replace
water and mineral ions lost during
sweating
 there are cheaper and equally
effective alternatives to branded
sports drinks.
Most students should be able to:
 explain that the water and mineral ions
lost by sweating during exercise need
to be replaced to avoid dehydration
 describe the composition of sports
drinks
 describe how sports drinks restore the
concentration of the body fluids
 evaluate the claims made by the
manufacturers of sports drinks.
Some students should also be able to:
 assess the value of using sports drinks
or alternatives after different levels of
exercise.
Most soft drinks contain water, sugar
and ions. [B3.1.1 d)]
Sports drinks contain sugars to
replace the sugar used in energy
release during the activity. They also
contain water and ions to replace the
water and ions lost during sweating.
[B3.1.1 e)]
If water and ions are not replaced,
the ion / water balance of the body is
disturbed and the cells do not work
as efficiently. [B3.1.1 f)]
Evaluate the claims of
manufacturers about sports drinks.
[B3.1]
WebQuest: Sports
drinks
Lesson structure
Support, Extend and Practical notes
Starters
Sweating it out – Show a picture of a very sweaty face. Ask if students can remember the
last time they were so hot that sweat was running down their face. Take examples. Ask if
anyone has had sweat running into their eyes and what this feels like. Draw out that it is
irritating because of the salt in your sweat. Ask where the salt has come from and draw out
any consequences of losing salt from the body. (5 minutes)
Half time! – Show photographs or video of footballers or rugby players at half time taking drinks.
Get the students to discuss with a friend what they would recommend the coach to put in the
drinks bottles and why. Support students by handing out some clue cards to assist in forming and
recording their opinions. Extend students by asking them how they would go about finding out the
correct quantities of ingredients to put into the drinks. (10 minutes)
Main
 When analysing sports drinks, give the students a photocopied range of labels from
different drinks, some of them should be sports drinks and some of them normal soft
drinks (non-branded) as being beneficial for sports and some fruit juices. Get the
students to analyse the contents of the drinks, drawing up some comparative bar
charts so as to visualise the differences easily. Have different groups report their
findings and discuss among the class.
 Take a sports drink and heat it slowly for a long time so as to evaporate off the water
from it. Take the solid left and place a weighed sample of it in a deflagrating spoon.
Use it to heat a sample of water. Students can record the increase in temperature and
relate this to the energy content. If available, video footage of the use of a bomb
calorimeter would help here to get across the idea that the energy content can be
calculated.
 Get the students to look in close detail at advertisements for sports drinks. Draw out the
claims that are being made and look to see if there is any evidence given to back these up.
This activity can be extended by getting the students to carry out internet searches for sports
drinks advertisements. They can investigate the claims found within them, becoming aware of
the importance of key ‘get-out’ phrases such as ‘up to…’ Compare the constituents of sports
drinks with those of a can of cola or other soft drink.
 Discuss the morality of using performance-enhancing substances in sport. In particular,
discuss where the students think the line should be drawn with sports drinks. As a
discussion prompt, get them to imagine that a sports drink has been developed which
actually does significantly increase performance. What would the moral and ethical
issues be in response to this?
Plenaries
Sauna safety – Show a picture of a sauna and or steam bath. Ask the students to imagine
a scenario where a person takes repeated prolonged saunas in order to lose weight after
each session (use jockeys and boxers as examples). Write them a note to warn them of
the dangers they face and give guidance on how to avoid the dangers of dehydration and
salt loss. Support students by giving them a list of key terms and phrases to choose from.
Extend students by asking them to research the safe levels to which the human body can
be dehydrated. (5 minutes)
DIY sports drink – Using the information in the Student Book, come up with a
recommendation memo to junior athletes as to what they could effectively use as sports
drink, and support this with reasons. Students should make it clear and informative, but
fun. (10 minutes)
Support
Give students a set of yes/no tick lists for a
comparative pair of drinks, one of which is a sports
drink and one a standard soft drink. Read through the
labels/adverts for these, displaying them clearly and,
stopping at appropriate points, prompt responses from
the students in order to finish up with a set of
comparison sheets.
Extend
Get students to use the internet, to find out the
standards of proof which would be needed and
accepted in order to back up and legitimise any claim of
enhanced performance due to the use of a sports drink.
New AQA GCSE Science © Nelson Thornes Ltd 2011
Course
Subject
Topic
Pages
Biology
Biology
B3 1.4 Exchanging materials
– the lungs
Pages 220-221
Learning objectives
Learning outcomes
Specification link-up
Kerboodle
Students should learn:
 that many organ systems are
specialised for exchanging
materials
 that exchange surfaces in
humans and other organisms
are adapted to maximise
effectiveness
 that the lungs are especially
adapted for the exchange of
gases
 that the alveoli provide a large
surface area over which gases
can readily diffuse into and out
of the blood.
Most students should be able to:
 describe the features of
exchange surfaces that make
them effective
 describe the function of the
alveoli
 explain how the alveoli are
adapted for the efficient
exchange of gases.
 Some students should also be
able to:
 evaluate the importance of
adaptations which give
increased surface area to the
effectiveness of gas exchange.
Many organ systems are specialised for
exchanging materials. The effectiveness of an
exchange surface is increased by:
– having a large surface area.
– being thin, to provide a short diffusion path.
– (in animals) having an efficient blood supply.
– (in animals, for gaseous exchange) being
ventilated. [B3.1.1 h)]
Gas and solute exchange surfaces in humans and
other organisms are adapted to maximise
effectiveness. [B3.1.1 i)]
The size and complexity of an organism increases
the difficulty of exchanging materials. [B3.1.1 j)]
In humans:
– the surface area of the lungs is increased by the
alveoli. [B3.1.1 k)]
Bump up your
grade: In or out?
Lesson structure
Support, Extend and Practical notes
Looking at blood vessels – Students to get a partner to look closely as
they pull down their own lower lip as far as they comfortably can (care
with body fluids). Get them to observe the blood vessels that lie just
below the skin. Ask: ‘Can you see two different colours? Which and
why?’ They then reciprocate with the partner. (Safety: wash hands
before and after.) (5 minutes)
Exchange surfaces – Show a series of pictures of a variety of living
organisms (suggest protoctistans, seaweeds, worms, molluscs, etc., need
some obvious ones and some more obscure) and ask the students to write
down where gas exchange takes place. Support students by giving them a list
of locations (body surface, gills, lungs etc.) as prompts. Extend students by
giving them more of the obscure examples and getting them to give more
details of how the exchanges take place. (10 minutes)
Main
 Prepare and show the students a PowerPoint presentation of the
processes involved in gas exchange. This should include details from
a wide variety of animals. If the ‘Exchange surfaces’ Starter is used,
this could be a follow-up. It may be helpful to create a worksheet of
questions for students to answer after watching the presentation.
 Demonstrate what is meant by a concentration gradient (see
Demonstration support’).
 To take a closer look at alveoli – either, mount some lung tissue from
the sheep or pig’s lungs looked at earlier, or show students prepared
slides of lung tissue. Get them to comment on the blood supply and
the proximity of the capillaries to the air sacs. If there are red blood
cells on the slides, then it is possible to emphasise the thin nature of
the alveolar wall and the short diffusion paths for the gases.
Plenaries
‘Like a fish out of water!’ – Ask a student to describe what this phrase
means to them. Discuss with the class. Show a video of a fish floundering
around on land or ask any student who goes fishing to describe what
happens and why. (5 minutes)
O2 in, CO2 out – Give students cards to hold (or pin on badges on hats)
that represent the parts of the respiratory system. Let one student
represent ‘oxygen’ and get them to pass down the system and eventually
into the blood and to the cells, where they join with a student labelled
‘carbon’. They both come back up and out as ‘CO2’. Get the students
involved so that they describe what is happening at each stage. Support
students by walking them through the process. Extend students by
asking them to work collectively to write information cards for what
happens at each stage. (10 minutes)
Support
Reinforce the main vocabulary via the use of flash cards with the word
on the front and the definition on the back.
Get the students to work in pairs to test each other.
Extend
Ask students to research oxygen transmissibility in contact lenses. Which
factors are important? Are there similarities/differences between the
conditions in the lungs and in the eyes?
Demonstration support
Concentration gradients
Equipment and materials required
Visking tubing, potassium manganate(vii) solution, large beakers.
Details
Demonstrate what is meant by a concentration gradient by using two
pieces of Visking tubing, one filled with relatively concentrated potassium
manganate(vii) solution and the other one with a visibly more dilute
solution. Place both of them simultaneously into large beakers of water
either on top of an OHP projector (care not to spill on the electrics!) or
use a Flexicam or similar. Get the students to observe the different rates
of diffusion by noting the different rates at which the purple colour
spreads into the surrounding water. Ask the students what they think
would happen to the rate when the difference between the
concentrations inside and outside the tubing became smaller and ask
how they could prevent this? Draw parallels with what happens at gas
exchange surfaces.
Safety: Potassium manganate(vii) – CLEAPSS Hazcard 81
oxidising/harmful. Will stain skin.
New AQA GCSE Science © Nelson Thornes Ltd 2011
Course
Subject
Topic
Pages
Biology
Biology
B3 1.5 Ventilating the lungs
Pages 222-223
Learning objectives
Learning outcomes
Specification link-up
Kerboodle
Students should learn:
 that the lungs are located in
the thorax, protected by the
ribcage and separated from
the abdomen by the
diaphragm
 that air is taken into the body so
that oxygen from the air can
diffuse into the bloodstream and
carbon dioxide can diffuse out
 that the movement of air into
and out of the lungs is called
ventilation and is achieved by
movements of the ribcage and
the diaphragm.
Most students should be able to:
 describe the structure of the
lungs and the breathing
process
 explain how movements of the
ribcage and the diaphragm
bring about changes in volume
and pressure in the thorax.
Some students should also be
able to:
 distinguish between the effects
of the two sets of intercostal
muscles
The lungs are in the upper part of the body (thorax),
protected by the ribcage and separated from the
lower part of the body (abdomen) by the diaphragm.
[B3.1.2 a)]
The breathing system takes air into and out of the
body so that oxygen from the air can diffuse into the
bloodstream and carbon dioxide can diffuse out of
the bloodstream into the air. [B3.1.2 b)]
To make air move into the lungs the ribcage moves
out and up and the diaphragm becomes flatter.
These changes are reversed to make air move out
of the lungs. The movement of air into and out of the
lungs is known as ventilation. [B3.1.2 c)]
Evaluate the development and use of artificial aids to
breathing, including the use of artificial ventilators. [B3.1]
Controlled Assessment: B4.3 Collect primary and
secondary data. [B4.3.1 a)]
Animation:
Ventilation and
gaseous
exchange
Lesson structure
Support, Extend and Practical notes
Starters
How did that happen? Ask the students to take a deep breath, hold it, then let it out. Get
them to write down then discuss their understanding of the mechanisms of ventilation.
Support students by prompting. Extend students by encouraging them to provide a more
detailed scientific response. (5 minutes)
Coughing your lungs out – What if someone did actually cough their lungs inside out? What
would it look like when the structures were inverted? Ask the students to describe the structures
they would see. (10 minutes)
Main
 Using a bell jar, a sheet of rubber and two balloons, it is possible to make a working
model of the thorax. The bell jar represents the thorax; the sheet of rubber is tied firmly
around the base and represents the diaphragm; the two balloons, representing the lungs,
are attached to the two branches of a Y-shaped glass tube, which is inserted through the
cork at the top of the bell jar. When the ‘diaphragm’ is pulled downwards, the ‘lungs’
should inflate. Get the students to describe and explain what is happening. Ask: ‘In what
ways does this differ from a human thorax?’
 Use a syringe with your finger on top to demonstrate how increasing the volume of a
container decreases the pressure within it and that if it is open to the atmosphere then air
will be drawn in due to being at a higher pressure on the outside than on the inside.
Draw a parallel with vacuum cleaners.
 Obtain the lungs and trachea of a sheep or pig from a local butcher (find one where they
slaughter their own or can get them for you when given notice). Create a worksheet for
students so that they can fill in details of colour, texture, size and what happens when air
is introduced into the trachea via a hose. When attaching a hose (or bellows) to the
trachea, make sure the joint is airtight. Safety: Wash hands. Do not use your mouth to
blow into the lungs. Use a cycle pump or foot pump to inflate the lungs. Keep the lungs in
a large plastic bag to contain aerosols. CLEAPSS leaflet P5S64.
 Following the exercise above, show the students some (uncooked) spare ribs – a rack of
ribs if possible. Observe the muscles and the cartilage and link with how they are
arranged in the thorax. This introduces the idea that there are muscles controlling the
movements of the ribcage. Show them the internal intercostal and the external
intercostal muscles.
 You may wish to carry out an analysis of inhaled and exhaled air (see ‘Practical support’).
Plenaries
Breathing through your chest – Show the students a suitable picture of a chest wound
such as a stab. Relate a true anecdote of a student who was climbing spiked railings and fell
on them, piercing his ribcage but not his lungs. When he looked at the wound it was frothing
and as he tried to breathe in, air was going into the wound. When he tried to breathe out air
was bubbling out of it. Ask the students to explain why this would happen. Relate that the
student solved the problem by holding a credit card to the wound tightly until medical help
arrived. Ask why this would work. (5 minutes))
Air flow – Get students to build up a flow chart of how air passes into the respiratory system
and out again, naming the structures and processes involved. This will be useful as a
revision aid. Support students by providing them with the stages which they should put in the
correct order. Extend students by asking them to annotate their flow charts with the pressure
and volume changes and include more details. (10 minutes)
Support
Get students to make a large cut-out and-stick model
of the thorax.
Extend
Ask students to produce an ‘I’ll guess that organ’
competition using minimal clues to guess the part of
the respiratory system chosen. Spelling clues such
as initial letters not allowed. Get them to write the
clues down and count the letters. The winner
produces the smallest successful clue.
Practical support
Comparing air breathed out and air breathed in
Equipment and materials required
Two boiling tubes, two 2-hole bungs, two short
delivery tubes (90° bend), two long delivery tubes
(90° bend), one boiling tube rack, limewater, CO2
indicator, eye protection.
Details
For the experiment illustrated in the Student Book,
you will need sets of apparatus made up as shown. If
students are using this apparatus, they should be
supervised. As an alternative to limewater,
hydrogencarbonate indicator could be used. It will be
cherry red when in equilibrium with atmospheric air,
but turns yellow as carbon dioxide is bubbled through
it. A more sophisticated experiment using a J-tube to
analyse the oxygen and carbon dioxide content of
inhaled and exhaled air was described in lesson B2
5.1, ‘Controlling internal conditions’. If it was not done
earlier, it would fit in well here. If it was done, then
students could be reminded of the experiment and
the results compared with the table given in the
Student Book.
Safety: Eye protection. CLEAPSS Hazcard 18
Limewater – irritant. CLEAPSS Recipe Card 34
Hydrogencarbonate indicator.
New AQA GCSE Science © Nelson Thornes Ltd 2011
Course
Subject
Topic
Pages
Biology
Biology
B3 1.6 Artificial breathing
aids
Pages 224-225
Learning objectives
Learning outcomes
Specification link-up
Students should learn:
 what happens if the surface
area of the gas exchange
surface in the lungs is reduced
or you can’t use your muscles
to ventilate your lungs
 whether a machine can
breathe for you
 how effective artificial lungs
are.
Most students should be able to:
 explain what happens if the surface area of
the gas exchange surface in the lungs is
reduced or you can’t use your muscles to
ventilate your lungs
 describe how a machine can breathe for you
 evaluate, in a simple way, the relative benefits
of different types of artificial lung.
Some students should also be able to:
 explain and evaluate the above in more detail.
Evaluate the development and
use of artificial aids to breathing,
including the use of artificial
ventilators. [B3.1]
Kerboodle
Lesson structure
Support, Extend and Practical notes
Starters
Smoking monkey – Show the students a picture of a smoking monkey toy
from the last century. Ask them to speculate how the toy could make the model
monkey draw air into itself. Ask: Would it be possible to make a machine that
would do the breathing for you? How might it work? Discuss. Support students
by providing prompts. Extend students by encouraging them to provide
reasoned and informative responses. (5 minutes)
Whales and Spaceships – In the Bible, a man called Jonah is
swallowed by a whale and lives inside it for three days and three nights
before emerging unharmed. Suppose that Jonah held his breath while
the whale dived to the bottom of the sea? Ask: What would happen to
Jonah’s ribcage? Suppose that Jonah on emerging from the whale, had
been picked up by a passing spaceship and dumped out above the
atmosphere. Again he holds his breath. What would happen now, with no
pressure at all on his ribcage? Get the students to write down and share
responses. Link in to methods of artificial breathing. (10 minutes)
Main
 Use exposition, video and internet images to illustrate the narrative of
the Student Book and discuss each of the points as they arise. If an
interactive whiteboard is available, use this to assemble ideas for use
in a further activity to construct a mindmap.
 Get the students to make a concise set of notes on the topic in bullet
point form.
 You might take advantage of a practical opportunity here by
measuring lung volume (see ‘Practical support’). If the results from a
number of volunteers are collected, the variations in lung volume can
be discussed. Are these variations related to size? Level of fitness?
How much variation is there within the group?
 Using the information in the text (students could be extended by
carrying out their own research), either in small groups or individually,
produce a mindmap showing the different types of artificial breathing
apparatus, their functions and relative advantages and
disadvantages. If this is done in groups, photocopy the end product
and give one to each member.
Plenaries
Mindmap share – Pass the mindmap produced earlier on in the lesson
around other students. Get them to add various extra pieces to it if they
see any omissions. (5 minutes)
Lung programming role-play – Split the class into groups of three. One
person should play the role of a computer programmer, another a doctor
and the third a patient with defective breathing. Discuss the requirements
of a computer programme which would respond to the patient’s needs for
breathing at different rates at different times. (Discourage any
conversations which stray into inappropriate territory.) Support students
by giving them suggested activities to work out. Extend students by
encouraging them to be creative in their suggestions. (10 minutes.)
Support
Give students slips of paper with the key words and ask them to
complete the sentences in the first summary question.
Extend
Get students to research the system of breathing used during a heartlung transplant operation.
Practical support
Measuring lung volume.
Equipment and materials required
5 litre translucent plastic bottle, water, glass trough, rubber tubing.
Details
Explain that for a positive pressure ventilation system, it is very important
that the volume of air introduced does not exceed the volume of the
lungs themselves or there will be trouble! Have an empty, clean 5 litre
translucent plastic bottle, clearly marked every half litre from the bottom
to the neck. Markings should be upside down so as to be readable when
the bottle is inverted. Fill the bottle with water and invert it over water in a
glass trough with 1 cm or more depth in the bottom. Ensure that the
capacity of the trough more than exceeds that of the bottle plus the water
in the bottom of the trough. Place the end of a rubber tube under the
neck of the bottle (a beehive shelf may help). Ask a volunteer to take a
deep breath and then exhale slowly and completely. Read off the volume
of air in the bottle and refill it for the next volunteer.
Safety: Use replaceable mouthpieces or wash the tube in sanitising fluid
then rinse before reuse.
New AQA GCSE Science © Nelson Thornes Ltd 2011
Course
Subject
Topic
Pages
Biology
Biology
B3 1.7 Exchange in the gut
Pages 226-227
Learning objectives
Learning outcomes
Specification link-up
Students should learn:
 that the villi increase the
surface area of the small
intestine
 that the villi have an extensive
network of capillaries to absorb
the products of digestion
 that the products of digestion
are absorbed by diffusion and
active transport.
Most students should be able to:
 describe the adaptations of the small
intestine that increases the efficiency
of absorption
 describe the structure of a villus.
Some students should also be able to:
 explain in detail how food is moved
from the gut into the blood by active
transport as well as diffusion.
In humans: …
– the surface area of the small intestine
is increased by villi. [B3.1.1 k)]
The villi provide a large surface area,
with an extensive network of capillaries,
to absorb the products of digestion by
diffusion and active transport. [B3.1.1 l)]
Kerboodle
Lesson structure
Support, Extend and Practical notes
Starters
Getting through the gut wall – Make block models with the names of some large food
molecules, such as starch and proteins, out of similar building bricks. Use stickers on the
front of the block models to spell the name of the big molecule. Use smaller stickers on the
backs of the individual bricks with the name(s) of the individual smaller molecules which go
to make up the big molecule. Use plastic knives, representing enzymes to cut them up. A
mixture of the large molecules and the smaller ones is placed into a Christmas tree net, or
similar large mesh bag. Ask: ‘Which ones go through?’ (5 minutes)
Efficient absorption – Spill some water on purpose next to a student (avoiding them and
any of their possessions). Give them a piece of cloth with poor absorbent qualities (e.g. a
piece of nylon) and ask them to clean it up. Do the same next to another student, but give
them a fluffy towel to dry it up with. Draw out in discussion as to why the towel is so much
better than the nylon. Support students by giving them some clues and prompts. Extend
students by getting them to explain what is happening in terms of SA (surface area) and
permeability. Link this to the digestive system. (10 minutes)
Main
 There are some good scanning electron micrographs, but other prepared sections may
be difficult to interpret, unless accompanied by a diagram.
 Allow time for students to view sections of a small intestine for themselves and to note
the capillary network. It is possible to present the small intestine as having two important
functions: it provides a large SA (surface area) for the completion of digestion, as well as
for the absorption of the products of digestion.
 Provide diagrams or use the Student Book to help the students identify the structures in
both the ileum and the villi.
 There are several websites where it is possible to download endoscope pictures of the
small intestine. A video sequence could be shown to students separately. Search the
Internet for ‘video endoscopy’.
 The importance of the digestion of large, insoluble molecules into smaller, soluble ones
can be demonstrated by using Visking, or dialysis tubing to model the gut.
 These experiments have already been described in B2 4.4 ‘Enzymes in digestion’.
Several different experiments were described and it could be appropriate here to set up
any that were not done.
 Students could be asked to design an experiment to show the need for the digestion of
large molecules, such as starch, into smaller insoluble sugars that could pass through
the gut wall. They could then use their previous knowledge to help them.
Plenaries
How big are your intestines? – Go to the gym or a large outdoor space and mark out an
area of 2000 m2, or tell the students the equivalent area in football pitches if it is not feasible
to find a large space. Describe this as being the SA (surface area) of your intestines when
fully spread out. Ask: ‘How can this be?’ Back in the lab, give each group of students a ball of
string and a small matchbox. Run a competition to see which group can get the longest piece
of string inside the matchbox. Link this with the length of the small intestine in the abdominal
cavity. (5 minutes)
A bacon sandwich: my story – Describe the fate of a bacon sandwich from eating it to the
defecation of the remains. Draw out what happens to all the parts, the bread, the butter and
the bacon. Support students by using writing frames and being given support material if
needed. Extend students by getting them to include details of exactly where the breakdown
and absorption takes place. This could be started in class and students finish it off for
homework. (10 minutes)
Support
Get students to make a model ileum by sticking
towelling to the inside of a wide-bore, flexible, plastic
pipe (or pink rain jacket sleeve) and then invert it.
Place wicks into the model and lead them to the
pipes, symbolising the blood supply.
Extend
Get students to use geometry to work out the surface
area to volume ratio of a 10 cm length of smooth
tube, one with a hundred villi per cm2 and one with
one hundred microvilli per villus. Each villus is 2 mm
in length and 0.2 mm in diameter. Each microvillus is
100 microns in length and 10 microns in diameter.
For ease of calculation, they can assume perfect
cylinders. They then use the formula πr2D for surface
area, where π = 3.14, t 5 radius of villus or
microvillus and D 5 length of villus or microvillus.
New AQA GCSE Science © Nelson Thornes Ltd 2011
Course
Subject
Topic
Pages
Biology
Biology
B3 1.8 Exchange in plants
Pages 228-229
Learning objectives
Learning outcomes
Specification link-up
Kerboodle
Students should learn:
 that carbon dioxide enters the
leaf cells by diffusion through
stomata
 that most of the water and
mineral ions are absorbed by
root hair cells
 that the root hairs increase the
surface area of the roots and
the flattened shape and
internal air spaces increase
the surface area of the leaves.
Most students should be able to:
 describe how leaves are adapted for
gaseous exchange
 describe how roots are adapted for
the efficient uptake of water and
mineral ions.
Some students should also be able to:
 explain why plants do not need
carbon dioxide from the air
continuously
 apply the principles of exchange
surfaces to exchange mechanisms
in plants.
In plants:
– carbon dioxide enters leaves by diffusion
– most of the water and mineral ions are
absorbed by roots. [B3.1.3 a)]
The surface area of the roots is increased
by root hairs and the surface area of
leaves is increased by the flattened shape
and internal air spaces. [B3.1.3 b)]
Plants have stomata to obtain carbon
dioxide from the atmosphere and to
remove oxygen produced in respiration.
[B3.1.3 c)]
Maths skills:
Calculating leaf
surface area
Support: Stomata
Lesson structure
Support, Extend and Practical notes
Starters
Revising leaf structure – Give each student a blank diagram of the external structure of
a leaf, and a diagram of a transverse section through a leaf with the different tissues
drawn in but not labelled. Support students by giving them a list of the names of the parts
with which to label the diagrams. Extend students by asking them to add the functions as
annotations to the labels. (5 minutes)
Round leaves versus flat leaves – Give each student a cube of modelling clay and measure
its volume and then to make a round thick leaf shape with it. Measure the SA (surface area) by
placing on graph paper and drawing round it. Then ask them to flatten the leaf and make it as
thin as possible. Measure the new SA and work out the SA:V of both leaves. Relate this
increase in SA to the greater efficiency of gas exchange. (10 minutes)
Main
 Observe the stomata using nail varnish (see ‘Practical support’). Having made ‘peels’
of the lower epidermis of the leaf, the students could investigate the upper epidermis,
comparing the numbers of stomata on each side. Ask: ‘Are they the same? Which
surface has the greater number?’
 The density of the stomata can be determined. The area of the leaf can be found by
drawing around it on graph paper and counting the number of squares. Using a
calibrated eye piece graticule in the eyepiece of the microscope, the number of
stomata in a field of view of known area can be counted and hence the total number
of stomata on the leaf or the number per cm2 can be calculated.
 Give each student a leaf (could be the one they will use to make a nail varnish peel)
and project a transverse section through a leaf showing all the cells. You will need a
good section that shows a distinct palisade layer and a definitely spongy mesophyll
with large air spaces. Get the students to write down all the features that they think
are adaptations enabling efficient gaseous exchange, both externally and internally.
Gather the information together and make a list on the board.
 Look at stomata on some fresh leaves (privet is good).
 Use binocular microscopes to observe the root hairs on young cress seedlings. If
cress seeds are sown on damp filter paper in Petri dishes, they will germinate and
the roots will grow in a few days. Provided that the atmosphere in the dish is kept
moist, it should be possible to see the root hairs with a microscope. Use prepared
slides of longitudinal sections through young roots to show root hairs and, if possible,
carry out measurements. Find out how far the root hair region extends. Ask: ‘Can
you see young root hairs developing or older root hairs breaking down?’
Plenaries
Transplant – Get students to explain why it is important to keep a ball of soil around
seedlings or bedding plants when you plant them out. Ask: ‘Why do young trees come
from the nursery with their roots in a ball of soil?’ (5 minutes)
What was your journey like? – In small groups, students should write a conversation
between a water molecule, a carbon dioxide molecule and a mineral ion as they meet in
a leaf. They should describe their journeys to get there (as people go on about roads and
journeys as small talk at parties) and ponder their fate. Support students by giving them
support material and using writing frames. Extend students by encouraging them to
include more detail and consideration of concentration gradients. (10 minutes)
Support
Use a modification of the Starter ‘Round leaves versus
flat leaves’. Give each student a block of modelling clay
and see who can make the largest, thinnest leaf. Give
them a jumbled sentence to complete on why a large
surface area is an adaptation.
Extend
Get students to investigate the root systems of plants
growing in different environments to see how they are
adapted for the efficient uptake of water and mineral ions.
They can compare root systems of some desert plants
and dune plants with typical flowering plants.
Practical support
Looking at stomata
Equipment and materials required
Fresh privet leaves, clear nail varnish, paintbrushes,
forceps, microscope slides and cover slips, microscopes.
Details
Apply a thin layer of clear nail varnish to the lower
surface of the leaf. Allow the nail varnish to dry and then
carefully peel it off using forceps. Place the ‘peel’ in a
drop of water on a microscope slide and cover it with a
cover slip. Look at the slide using the low power of the
microscope. The stomata should be visible, but use the
high power of the microscope to see the more detailed
structure, including the guard cells.
Safety: Nail varnish is flammable and the vapour is
harmful.
New AQA GCSE Science © Nelson Thornes Ltd 2011
Course
Subject
Topic
Pages
Biology
Biology
B3 1.9 Transpiration
Pages 230-231
Learning objectives
Learning outcomes
Specification link-up
Kerboodle
Students should learn:
 that water is lost through the
leaf by evaporation through
the stomata on the leaves of
a plant
 that the rate of transpiration
is more rapid in hot, dry and
windy conditions
 that when plants lose water
faster than it is replaced, the
stomata can close to prevent
further wilting.
Most students should be able to:
 explain why transpiration occurs
 describe the effect of
environmental conditions on
transpiration
 explain how water loss may be
controlled.
Some students should also be
able to:
 explain how to compromise
between the need for carbon
dioxide and water loss.
Plants mainly lose water vapour from
their leaves. Most of the loss of water
vapour takes place through the stomata.
– evaporation is more rapid in hot, dry
and windy conditions
– if plants lose water faster than it is
replaced by the roots, the stomata can
close to prevent wilting. [B3.1.3 d)]
The size of stomata is controlled by
guard cells, which surround them.
[B3.1.3 e)]
Controlled Assessment: B4.1 Plan
practical ways to develop and test their
own scientific ideas. [B4.1.1 a) b)]; B4.3
Collect primary and secondary data.
[B4.3.1 a), B4.3.2 b) c)]
How science works: What
factors affect how quickly a
plant takes up water?
Animation: Transpiration
Interactive activity: Exchange
of materials
Revision podcast: Exchange of
materials
Test yourself: Exchange of
materials
On your marks: Exchange of
materials
Examination-style questions:
Exchange of materials
Answers to examination-style
questions: Exchange of
materials
Teacher notes: Exchange of
materials
Lesson structure
Support, Extend and Practical notes
Starters
What has been happening to our plant? – Using the potted plant set up at the end of the
previous topic, look at the results (observe the cobalt chloride paper if used or check the
weight of the plant with its pot covered in the plastic bag) and ask students to write a
sentence explaining what has caused the changes. Support students by prompting. Extend
students by encouraging them to provide a detailed explanation. (5 minutes)
How does water get to the top of trees? – Ask the question then work in groups, with
students to write down their ideas on large sheets of paper. Share results. (10 minutes)
Main
 You can model transpiration by placing a wick through a drinking straw and clip the
wick to a small piece of card with blotting paper attached to it, to imitate a leaf. Place
the imitation leaf into a boiling tube containing dyed water. The water will travel up the
wick and evaporate from the blotting paper.
 To cover investigative aspects of ‘How Science Works’, the variables, such as leaf
size, temperature and wind speed, can be altered and the rate of transpiration can be
ascertained by weight loss under these different conditions.
 This exercise lends itself to group work. One group could investigate leaf size, another,
the effects of temperature, and so on. They need to report back at the end of the
practical session.
 Potometers measure the rate of water uptake, which is linked with the rate at which
water evaporates from the leaf surface. The best plant material to use is a woody twig,
which can be firmly attached to the tubing. It is important that there are no bubbles in
the system and that the whole apparatus is watertight.
 Once set up, it needs to be left to allow the plant to settle down after the handling.
Introduction of air bubble enables measurements of the water uptake to be made.
Either the distance travelled by the bubble in a set time or the time taken for the bubble
to travel a set distance can be measured.
 Discuss reliability and precision of measurements (‘How Science Works’). Repetitions
are necessary to calculate a mean rate under each set of conditions.
 This exercise can be used to develop many ‘How Science Works’ concepts:
predictions can be made, hypotheses formulated, measurements taken and the results
plotted. It provides a good opportunity to concentrate on developing areas of relative
weakness with individuals in the group.
Plenaries
Sequencing session – Make cards of the stages in the process of transpiration from
water uptake in the soil to evaporation from the leaf cells. Get students to put these into the
correct order. This makes an excellent summary for a revision card. (5 minutes)
Graph interpretation – Give students a graph of the transpiration rate of a plant over 24
hours. Break it into sections labelled with letters. The students have to explain why the rate
changes at different times of day. Support students by providing them with the reasons for
the changes and they have to link these to the letters on the graph. Extend students by
encouraging them to think of as many different reasons as they can for each section, as
there could be different explanations for some sections. Check all explanations at the end
of the session. (10 minutes)
Support
Use pre-printed tables and graphs with the axes
already drawn to carry out a mass–loss experiment
with two plants, one exposed to moving warm air e.g.
from a hair dryer. This can be done on a large scale
using two spring balances at the front or individually
(with assistance if available). Remember to cover the
pots of the plants with polythene bags, or to make sure
there is no water evaporating from anywhere except
the aerial parts of the plants.
Extend
Get students to consider:
– What would limit the height to which water can travel
up a tree trunk?
– How would you estimate the leaf SA (surface area) of
a whole tree?
– How could you investigate the effect of humidity on
the transpiration rate?
Practical support
Evidence for transpiration
Equipment and materials required
One potometer per group, preferably set up with the
shoot inserted, electric fan to create air movements,
bench lamps to provide light hair dryer to provide
warmer temperature (but it will create air movement as
well), petroleum jelly to block stomata.
Details
It is important that there are no bubbles in the system and
that the whole apparatus is watertight. Once set up, it
needs to be left to allow the plant to settle down after the
handling. Introduction of an air bubble enables
measurements of the water uptake to be made. Either the
distance travelled by the bubble in a set time or the time
taken for the bubble to travel a set distance can be
measured. The electric fan will increase the air
movements, the bench lamps will allow the effect of light
to be investigated and the hair dryer allows the effect of
temperature to be investigated. The effect of changing
the leaf area can also be investigated, either by removing
some of the leaves or by blocking the stomata with
petroleum jelly. It is possible to calculate the uptake per unit
area by measuring the total area of the leaves.
Safety: Take care with electrical equipment.
New AQA GCSE Science © Nelson Thornes Ltd 2011