Scheme of work

Cambridge O Level
Biology
5090

Scheme of work Cambridge O Level Biology (5090)

Contents
Overview............................................................................................................................................................................................................................................................. 3
Unit 1: Cells and cell processes ...................................................................................................................................................................................................................... 6
Unit 2: Plant nutrition and transport ............................................................................................................................................................................................................. 13
Unit 3: Animal nutrition................................................................................................................................................................................................................................... 21
Unit 4: Human transport and respiration ...................................................................................................................................................................................................... 28
Unit 5: Coordination, response, movement and homeostasis ................................................................................................................................................................... 36
Unit 6: Drugs, microorganisms and biotechnology .................................................................................................................................................................................... 44
Unit 7: Organisms and the environment ....................................................................................................................................................................................................... 49
Unit 8: Continuity of life reproduction ....................................................................................................................................................................................................... 56
Unit 9: Continuity of life inheritance and evolution .................................................................................................................................................................................. 65

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Cambridge O Level Biology (5090)

Scheme of work Cambridge O Level Biology (5090)

Overview
Recommended prior knowledge
Since this syllabus involves a consideration of its topics, very largely from first principles, little prior knowledge is required. The course has been divided into nine units,
with each unit having a common thread and following the sequence presented in the syllabus. The order of topics as presented gives a logical order for teaching.
Teachers may however wish to alter the suggested sequence, particularly in regions where marked seasonal variations restrict the availability of specimens at certain
times of the year.
Outline
The units within this scheme of work are:
Unit

Topic

Content (syllabus reference)

Teaching time (%)

Unit 1

Cells and cell processes

1 Cell structure and organisation

2 Diffusion and osmosis
3 Enzymes

15 %

Unit 2

Plant nutrition and transport

4 Plant nutrition
6 Transport in flowering plants

15 %

Unit 3

Animal nutrition

5 Animal nutrition

15 %

Unit 4

Human transport and respiration

7 Transport in humans
8 Respiration

11 %

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Unit

Topic

Content (syllabus reference)

Teaching time (%)

Unit 5

Coordination, response,
movement and homeostasis

9
10
11
12

11 %

Unit 6

Drugs, microorganisms and

biotechnology

13 The use and abuse of drugs

14 Microorganisms and biotechnology

8%

Unit 7

Organisms and the environment

15 Relationships of organisms with one another and with the

environment

8%

Unit 8

Continuity of life reproduction

16 Development of organisms and continuity of life

9%

Unit 9

Continuity of life inheritance and

evolution

17 Inheritance

8%

Excretion
Homeostasis
Coordination and response
Support movement and locomotion

Opportunities for differentiation are indicated as challenging or extension activities; there is the potential for differentiation by resource, length, grouping, expected level
of outcome, and degree of support by teacher, throughout the scheme of work. Length of time allocated to a task is another possible area for differentiation
Teaching order
The units may be taught in order, 1 to 9. This is not essential, but the following recommendations apply.
(a) It is recommended that Unit 1 is taught as the first unit of the course.
(b) Other units that are suitable for teaching early in the course include Units 2, 3 and 4. Some of the ideas met in earlier units are revisited in later units.
(c) It is recommended that the teaching of some skills and concepts are ongoing across all units.
Teacher support
Teacher Support is a secure online resource bank and community forum for Cambridge teachers. Go to http://teachers.cie.org.uk for access to specimen and past
question papers, mark schemes and other resources. We also offer online and face-to-face training; details of forthcoming training opportunities are posted online.

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Cambridge O Level Biology (5090)

An editable version of this scheme of work is available on Teacher Support. Go to http://teachers.cie.org.uk. The scheme of work is in Word doc format and will open
in most word processors in most operating systems. If your word processor or operating system cannot open it, you can download Open Office for free at
www.openoffice.org
Resources
An up-to-date resource list for this syllabus can be found at www.cie.org.uk
Textbooks:
The textbooks referenced have been written to accommodate this Cambridge O Level Biology syllabus (though it is advisable to check textbook content with the syllabus
before each unit, since the text may also contain some material relevant to other Cambridge International Examinations syllabuses).
Textbooks endorsed by Cambridge International Examinations for use with the Cambridge O Level Biology syllabus (syllabus code 5090) include:
Burton, I. J
Jones, G & Jones, M
Jones, M
Hayward, D

The Cambridge Revision Guide GCE O Level Biology Cambridge University Press, UK (2000) ISBN: 9780521723756
Biology International Edition for IGCSE and O Level Cambridge University Press, UK (2002) ISBN: 9780521891172
O Level Biology Oxford University Press, Pakistan (2010) ISBN: 9780195799828
Teaching and Assessing Practical Skills in Science Cambridge University Press, UK (2003) Professional Development for Teachers series.
ISBN: 9780521753593

Websites:
The suggested references are intended to provide support for learners and teachers following the course. Some resources directly support the suggested teaching
activities whilst others provide more general reference, background and extension material. All resources have been checked to ensure their relevance and academic
level is suitable for the Cambridge O Level Biology syllabus. All references are to specific web pages rather than to the general site URL and may be followed directly
from the electronic scheme of work or typed directly into the address bar of any web browser. A number of animation and video resources rely on the correct plug-in
software being installed on the users computer (e.g. QuickTime and Flash) all of which are freely available for download via the internet.
Cambridge International Examinations is not responsible for the accuracy or content of information contained in the listed websites. The inclusion of a link to an external
website should not be understood to be an endorsement of that website or the sites owners (or their products/services).
The particular website pages in the learning resource column were selected when the scheme of work was produced. Other aspects of the sites were not checked and
only the particular resources are suggested.
CD-ROMs:
GCE O Level Examinations Past Papers with Answer Guides Biology Foundation Book Cambridge University Press, India (2006) A CD and book of past examination
papers produced by Cambridge International Examinations ISBN: 9788175961784 available at
www.cambridgeindia.org/showbookdetails.asp?ISBN=9788175961784&category_id=SB
BIOSCOPE (2004) A CD of prepared microscope slides produced by Cambridge International Examinations, Cambridge-Hitachi, UK ISBN: 9781845650261

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Cambridge O Level Biology (5090)

Scheme of work Cambridge O Level Biology (5090)

Unit 1: Cells and cell processes
Recommended prior knowledge
Since this is a logical place to begin the course, no prior knowledge is essential. Nevertheless, it would be helpful if learners were already familiar with the use of a
microscope and with standard, safe laboratory technique. They might also know the basic principles of diagram drawing sharp HB pencil, drawings as large as can be
fitted into the available space (with room for labels, in upper case, in pencil with ruled label lines). A simple understanding of chemical molecules and chemical reactions,
the kinetic theory, solutions and pH would also be helpful.
Context
Cells are the building blocks of living organisms and basic physiological processes in which they are involved have relevance throughout the syllabus.
Outline
Structural features common to and different in plant and animal cells are considered. Specific examples show how the basic cell structure may be modified for different
functions. The involvement of cells in the processes of diffusion, osmosis and active transport is explained as is the importance and mode of action of enzymes.
Learning objectives

Suggested teaching activities

Learning resources
5090 past question papers are available at:
http://teachers.cie.org.uk
PowerPoint presentation: Cells and tissues
www.biology-resources.com/

Candidates should be able to:

1(a)

Examine under the microscope an

animal cell (e.g. from fresh liver) and a
plant cell (e.g. from Elodea, moss,
onion epidermis, or any suitable,
locally available material), using an
appropriate temporary staining
technique, such as iodine or methylene
blue

Use pre-prepared microscope slides to examine, compare and identify

structures in (i) epidermal cells peeled from the inner surface of an onion
bulb and stained with iodine solution; (ii) locally available plants with
leaves which display mesophyll cells adhering to the peeled-off
epidermis in order to show the presence of chloroplasts; (iii) freshwater
filamentous algae, Elodea or moss that can be mounted in a drop of
water on a slide and viewed under a microscope.
A more challenging activity is for learners to prepare their own slides of
the type described above and to prepare slides of fresh liver cells or
human cheek cells stained with methylene blue. Ask learners to
compare the structures seen in each of the slides they have prepared.

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Cambridge O Level Biology (5090)

Plant and animal cell structure diagrams

and explanations:
www.s-cool.co.uk/gcse/biology/
Illustrations of cells:
www.cellsalive.com/
Cell structure:
www.exploratorium.edu/

Learning objectives
1(b)

Draw diagrams to represent

observations of the plant and animal
cells examined above

1(c)

Identify from fresh preparations or on

diagrams or photomicrographs, the cell
membrane, nucleus and cytoplasm in
an animal cell

Suggested teaching activities

Video clip cell structure:

www.bbc.co.uk/learningzone/

Use slides prepared during practical work above to identify the

structures visible. Present learners with diagrams and photomicrographs
of a range of cell types to allow them to identify the named structures.
A more challenging activity is to use diagrams and photomicrographs
showing these structures within different types of cells with which
learners are unfamiliar.

1(d)

Identify from diagrams or

photomicrographs, the cellulose cell
wall, cell membrane, sap vacuole,
cytoplasm, nucleus and chloroplasts in
a plant cell

Learning resources

Textbooks:
Jones, M Unit 1 Cell structure
Burton, I J Topic 1 Cell structure and
organisation
Jones, G & Jones, M 1 Cells

Use slides prepared during practical work above to identify the

structures visible. Present learners with diagrams and photomicrographs
of a range of cell types to allow them to identify the same structures (and
those previously not visible).
A more challenging activity is to use diagrams and photomicrographs
showing these structures within different types of cells with which
learners are unfamiliar.

1(e)

Compare the visible differences in

structure of the animal and the plant
cells examined

Use the slides prepared and diagrams presented above to construct a

table of the similarities and differences between plant and animal cell
structure.
A more challenging activity is for learners to make models of a plant
cell and/or an animal cell to gain an idea of the orientation of the main
structures. Extend the task by asking learners to consider the limitations
of their models in comparison to actual cellular components.

1(f)

State the function of the cell

membrane in controlling the passage
of substances into and out of the cell

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Explain why the passage of substances must be controlled. Extend the

discussion by inviting learners to suggest chemicals that might pass in
either direction through the membrane (and some that may not pass
through). Extend further by asking learners to suggest reasons why such
substances may/may not enter the cell i.e. reasons that they are
needed within the cell or because they might harm the cell.

Cambridge O Level Biology (5090)

5090 5090 past paper question:

Jun 2011 Paper 21 Q8

Learning objectives

Suggested teaching activities

Learning resources

1(h)

Provide good diagrams of a root hair cell and of a red blood cell (in
surface view and in longitudinal section) for learners to label.
Alternatively learners may draw and label one of the specialised cells on
A3 paper and present their findings to other learners.

Adaptations of specialised cells:

www.bbc.co.uk/

State, in simple terms, the relationship

between cell function and cell structure
for the following:
absorption root hair cells
conduction and support xylem
vessels
transport of oxygen red blood cells

1(i)

Identify these cells from preserved

material under the microscope, from
diagrams and from photomicrographs

A more challenging activity is for learners to research a greater range

of specialised cells and their functions.

Red blood cell diagram:

www.s-cool.co.uk/assets/
Root hair cell diagram:
www.bbc.co.uk/schools/

Explain the importance of surface area to volume ratios and relate this to
the maximum rate and amount of uptake in cells marked*. Understand
that xylem vessels are dead and should not be called cells. Their walls
are strengthened for support. Since they have no cytoplasm, they are
hollow tubes for the conduction of water and mineral ions. Red blood
cells are biconcave discs to provide a large surface area for gas
exchange and to make the cell flexible enough to pass through small
capillaries.
Observe prepared slides of root hair cells, xylem vessels and red blood
cells under the microscope. Extend this practical work by asking learners
to make annotated drawings of a root hair cell and of red blood cells as
seen under the microscope.

Seed germination apparatus:

http://fromdirttodinner.files.wordpress.com/

A more challenging practical task is for learners to germinate their own

seeds (part-fill a specimen tube or glass jar with water and trap a seed
between the walls of the tube/jar and a piece of filter paper) and observe
the root hairs.

1(j)

Differentiate cell, tissue, organ and

organ system as illustrated by
examples covered in syllabus sections
112, 15 and 16

Explain the hierarchy of these structures and invite learners to supply

both animal and plant examples of each.

Hierarchy or organisation:
http://lgfl.skoool.co.uk/

Learners can draw a flow diagram from cells to a named organ system
to gain an understanding of the complexity of the human body.
An outline of the human body can be used to draw in the main organs
and organ systems of the body.
A more challenging activity is to prepare a set of cards - each with the

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Cambridge O Level Biology (5090)

Learning objectives

Suggested teaching activities

Learning resources

name and/or a diagram of one example of a cell, tissue, organ or

system. Learners may classify each card by placing them into groups
and then place the groups of cards in order of organisation level.
2(a)

Define diffusion as the movement of

molecules from a region of their higher
concentration to a region of their lower
concentration, down a concentration
gradient

Refer to chemical molecules always being in a state of random motion.

Explain the concept of concentration in gases and in liquids and the
tendency for molecules to move from where they are more concentrated
to where they are less concentrated.
Illustrate diffusion with an air freshener placed on one side of the
laboratory, with potassium manganate IV solution dropped with a pipette
into a large beaker of still water and with ammonia/hydrochloric acid
placed at opposite ends of a long glass tube lined with damp indicator
paper.
Explain that netting drawn across the room would not prevent the
diffusion of the molecules of air freshener since the mesh is too large to
inhibit their passage. Relate this analogy to the passage of molecules
through the cell walls of plants.
A more challenging practical task is for learners to investigate the effect
of surface area/volume ratio on the rate of diffusion by measuring the
time taken for alkali agar cubes of different dimension coloured with
phenolphthalein indicator to turn colourless when placed in dilute
hydrochloric acid.

PowerPoint presentation: Diffusion

www.biology-resources.com/biologyCD.html
Diffusion animation and explanation:
www.bbc.co.uk/schools/
Diffusion practical activities:
www.iit.edu/
Agar cube practical instructions:
www.practicalbiology.org/
Agar cube practical video:
www.youtube.com/
Textbooks:
Burton, I J Topic 3 Diffusion and
Osmosis (active transport also covered)
Jones, G & Jones, M 2 Diffusion,
Osmosis and Active transport
Jones, M Unit 2 Diffusion, Osmosis and
Active Transport.
5090 5090 past paper questions:
Nov 2011 Paper 22 Q1
Nov 2010 Paper 22 Q8

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Cambridge O Level Biology (5090)

Learning objectives

Suggested teaching activities

Learning resources

2(b)

Osmosis should be explained as a special case of diffusion, in which

only water molecules are able to move from one side of a partially
permeable membrane to another.

5090 5090 past paper question:

Jun 2011 Paper 61 Q1

Define osmosis as the passage of

water molecules from a region of their
higher concentration to a region of
their lower concentration through a
partially permeable membrane

Ensure that learners understand what a solution is in terms of particles,

so that they are able to imagine the water molecules and solute particles
behaving independently of each other.
Use Visking tubing to demonstrate that it allows water molecules to pass
but not sugar (sucrose) molecules. Set up a Visking sausage containing
a concentrated sucrose solution, attached to a length of glass tubing at
one end and submerged in a beaker of water at the other. Note the rise
in the level of sucrose solution. Extend the demonstration by asking
learners to draw the distribution of molecules before, during and after
and to explain their movement during the demonstration.

2(c)

Describe the importance of water

potential gradient in the uptake of
water by plants and the effects of
osmosis on plant and animal tissues

Relate uptake of water into cells with an increase in their volume and, as
a consequence of the cell wall, also of pressure within the cell. Explain
the importance of turgidity in the process of support. In the absence of a
cell wall animal cells will burst. Stress that during osmosis water
molecules ONLY move across a water potential gradient.

Visking tubing demonstration:

www.hyss.sg/
Osmosis animation and explanations:
www.bbc.co.uk/
www.s-cool.co.uk/

Video clips of osmosis in onion epidermal

cells:
www.youtube.com/
www.youtube.com/

Discuss differences in the effects of water uptake and loss on animal

cells that lack a cellulose cell wall and plant cells that have a cellulose
cell wall.
Learners may observe the effect of osmosis on plant cells using onion
epidermis mounted in pure water and in concentrated sugar solution and
viewed under a microscope. Extend this activity by asking learners to
make annotated diagrams of the observed cells/tissue.
A more challenging task is for learners to demonstrate the effect of
osmosis on plant tissue using measured lengths of raw potato chips or
dried raisins immersed in water and in sugar solution of different
concentrations. Extend this activity by asking learners to graph their
results in terms of sugar concentration vs change in mass of potato and

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10

Learning objectives

Suggested teaching activities

Learning resources

to explain the pattern of their results using osmosis theory.

Relate water uptake by osmosis to the structure of root hair cells
covered earlier in this unit.
2(d)

2(e)

Define active transport as the

movement of ions into or out of a cell
through the cell membrane, from a
region of their lower concentration to a
region of their higher concentration
against a concentration gradient, using
energy released during respiration

Explain the need for uptake of ions even when their concentration may
already be greater inside a cell or organism. Energy from respiration
must be used to counteract the effect of passive diffusion. No detail of
the molecular mechanism of active transport is required.

Discuss the importance of active

transport as an energy-consuming
process by which substances are
transported against a concentration
gradient, as in ion uptake by root hairs
and glucose uptake by cells in the villi

A challenging practical task is for learners to set up bean seedlings in

dilute fertiliser solution and to measure the nitrate concentration in the
water (using commercially available reagent strips) to show the effect of
active transport on the uptake of ions into the roots.

3(a)

Define catalyst as a substance that

speeds up a chemical reaction and is
not changed by the reaction

3(b)

Define enzymes as proteins that

function as biological catalysts

3(c)

Explain enzyme action in terms of the

lock and key hypothesis

Data task: active uptake

www.practicalbiology.org/

Explain the importance of active transport in the specific context of the

root hair cell and the intestinal villi.

A challenging data analysis activity is for learners to undertake the

active uptake data task detailed in the online resources column.
Revise the meaning of the term catalyst and relate to the use of the term
in chemistry.
Explain the function of a catalyst in terms of altering the rate of a
chemical reaction without itself being used up during the reaction.

Enzymes and their action:

www.bbc.co.uk/schools/
www.s-cool.co.uk/
www.abpischools.org.uk/

Introduce the terms substrate, product and active site. Use the online
resources to illustrate the nature of these structures. The analogy of the
lock and key is useful when explaining the mechanism of enzyme
action. Learners may produce and use 3D models of enzyme and
substrate molecules using clay to illustrate the hypothesis.

http://highered.mcgraw-hill.com/
Textbooks:
Jones, G & Jones, M 3 Enzymes
Jones, M Unit 3 Enzymes

3(d)

Investigate and describe the effect of

temperature and pH on enzyme
activity

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Explain in terms of heat and pH the effect of changing the shape of the
active site of an enzyme permanently in the case of extreme heat.
Reference to the difference between raw and cooked egg white may be
made. State that the rate of enzyme-controlled reactions increases to an

Cambridge O Level Biology (5090)

Burton I J Topic 4 Enzymes Topic 5

Nutrition (for food tests)

11

Learning objectives

Suggested teaching activities

Learning resources

optimum as increased heat supplies kinetic energy to increase the

speed of movement of both substrate and enzyme molecules. Enzymes
are then denatured or destroyed - but NOT killed.
Extend learners understanding by asking them to consider why some
enzymes may have a different optimum temperature to those found in
humans and to research specific examples.

5090 past paper question:

Nov 2011 Paper 62 Q1

Explain graphs of rate of enzyme reaction at different temperatures and

at different pHs. Provide learners with graphs and ask them to annotate
sections of the graph to explain the change in rate at each stage (e.g.
increase, optimum and decrease)

Enzyme action and graphs showing effect

of changing temperature and pH:
www.bbc.co.uk/schools/

Enzyme action and effect of temperature

animation:
www.biotopics.co.uk/

Explain the use of the iodine test for starch and Benedicts test for
reducing sugars. Learners should carry out the iodine test for starch and
Benedicts test for reducing sugars on prepared solutions of starch and
glucose before undertaking enzyme experiments.
Simple experiments using the enzyme catalase are appropriate as a
basic introduction, such as:

Catalase in potato tissue:

www.ngfl-cymru.org.uk/

i)

www.nuffieldfoundation.org/

the breakdown of hydrogen peroxide by catalase (e.g. in yeast or

potato)

This may be followed by experiments to show:

i)

ii)

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the effect of amylase on starch solution or lipase on lipids at

different temperatures and also to show the effect of boiling
enzymes before use

Effect of temperature on lipase:

www.nuffieldfoundation.org/

Effect of pH on amylase:
www.nuffieldfoundation.org/

the effect of pH on the same reaction at a constant temperature

Cambridge O Level Biology (5090)

12

Scheme of work Cambridge O Level Biology (5090)

Unit 2: Plant nutrition and transport
Recommended prior knowledge
Unit 1 will supply learners with valuable knowledge on the structure of plant cells as well as on diffusion, osmosis, and transport in the xylem. The basic structure of the
starch and sugar molecules should be understood. Energy will have been mentioned with reference to active transport, but learners should be aware that there are
different forms of energy and that it can be transformed from one form to another.
Context
This unit concentrates on the botanical relevance of topics covered in Unit 1 and forms a natural link with topics to be visited in several other units, notably Units 3 and 7.
Outline
Photosynthesis, as the process responsible for the production of food for all living organisms, is explained. The basic biochemistry of the process as well as the
conditions necessary for the process to occur, are considered. The structure and adaptation of a leaf and of leaf cells for photosynthesis are considered in some detail
and reference is made to carbohydrate as the starting point for protein synthesis. A knowledge of leaf structure allows learners to investigate the process of transpiration.
The unit generates many opportunities for practical work, but for centres operating in areas which experience marked seasonal change, some thought may have to be
given to the best time for studying the unit.
Learning objectives

Suggested teaching activities

Learning resources
5090 past question papers are available
at: http://teachers.cie.org.uk

Candidates should be able to:

4(a)

Understand that photosynthesis is the

fundamental process by which plants
manufacture carbohydrates from raw
materials

Explain that photosynthesis is a plants method of nutrition. Only small

molecules can be absorbed (by diffusion and osmosis) and these are
used by the plant to build larger molecules. Explain that energy is required
to construct the larger molecules and is obtained as light energy. Some of
this energy remains locked away (as chemical energy) in the molecules of
carbohydrate produced.

Photosynthesis diagrams and

explanations covering several learning
objectives in this unit:
www.bbc.co.uk/schools/
www.s-cool.co.uk/
Textbooks:
Jones, G & Jones, M 5 How Green
Plants Feed

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13

Learning objectives

Suggested teaching activities

Learning resources
Jones, M Unit 4 Photosynthesis
Burton, I J Topic 6 Plant Nutrition

4(b)

Investigate the necessity of

chlorophyll, light and carbon dioxide for
photosynthesis, using appropriate
controls

For chlorophyll, learners should use a plant with variegated leaves e.g.
variegated Pelargonium. Any locally available variegated leaf will
suffice, however trial the experiment first to check that it stores starch,
not sugar (common in monocot plants).

For light, use aluminium foil or black paper held either side of a leaf
using paperclips.

For CO2, place the plant under a bell jar, or similar, containing a
beaker of concentrated sodium hydroxide solution to absorb CO2. This
may be more suited to a whole-class demonstration.

Include in all cases the importance of starting with a de-starched plant.

Explain the importance of controls in scientific practice and invite learners
to list the variables which must be controlled during the above
investigations. Stress the importance of keeping all variables constant
other than the one being investigated.

Practical to investigate the factors

affecting photosynthesis:
www.practicalbiology.org/

Animation showing starch test procedure:

www.footprints-science.co.uk/
5090 past paper question:
Nov 2011 Paper 31

It is advisable to demonstrate the steps of the starch test on a leaf before

allowing learners to carry it out. If a naked flame is used for heating, stress
the danger of using flammable liquid and the need for safety precautions.
Learners may summarise their practical work in the form of a flow chart
illustrating the steps involved and the scientific reasons for each step.
4(c)

State the equation (in words or

symbols) for photosynthesis

An equation in words is adequate, however if given, an equation in

symbols, it must balance. In both cases, light energy rather than just
energy should be specified.

4(d)

Investigate and state the effect of

varying light intensity, carbon dioxide
concentration and temperature on the
rate of photosynthesis (e.g. in
submerged aquatic plants)

Learners may first be shown a water plant evolving bubbles of oxygen as

it photosynthesises in bright light. Then invite learners to suggest how
they might investigate the effect of varying light intensity, temperature or
carbon dioxide.

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Cambridge O Level Biology (5090)

Practical to investigate the effect of light

on photosynthesis in an aquatic plant:
www.practicalbiology.org/

14

Learning objectives

Suggested teaching activities

Learning resources

A challenging activity for learners is for them to plan their own

investigation into the effect of one of these factors. Different groups of
learners may investigate a different factor allowing for collaborative
discussion following the practical work. If available the aquatic plant
Cabomba is a reliable alternative to the commonly used Elodea.

Elodea investigation apparatus and effect

of factors:
www.nuffieldfoundation.org/

Extend the practical work by providing learners with a microscope to view

a leaf from the plant in order to show the presence of chloroplasts.
All experiments here are modifications of that in which a water plant is
submerged in a container of water. The rate of photosynthesis is
determined by measuring volumes or counting bubbles of O2 released as
the plant is exposed to one altered variable. The concentration of CO2
may be altered by adding varying amounts of sodium hydrogen carbonate
to the water.
An extension practical activity is for learners to investigate the floating
behaviour of leaf discs due to the evolution of O2 gas during
photosynthesis in different conditions.
4(e)

Understand the concept of limiting

factors in photosynthesis

The required factor which is in the shortest supply limits the rate at which
a plant will photosynthesise. Show by a simple graph that the rate of
photosynthesis levels off with increased availability of CO2 or light. Extend
learners thinking by inviting them to suggest an explanation for this and
asking them to predict what might happen if the availability of the limiting
factor is increased.

Interactive activity:
www.kscience.co.uk/

Investigating the behaviour of leaf discs:

www.saps.org.uk/
5090 past paper question:
Nov 2010 Paper 61 Q1
See online resources listed against 4(a).
5090 past paper question:
Nov 2010 Paper 21 Q8a

A more challenging activity is for learners to plot the results of the

previous experiment from 4(d) to show how light acts as a limiting factor.
Plot rate of reaction (bubbles of O2 released per minute) against light
intensity (equal to 1/d2 where d is the distance from the light source to the
plant). Extend learners thinking by asking them to present verbal and
written explanations of their data to other learners.
4(f)

Describe the intake of carbon dioxide

and water by plants

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Carbon dioxide from the atmosphere and water from the soil are small
molecules which are used to construct the larger glucose molecules
formed during photosynthesis.

Cambridge O Level Biology (5090)

15

Learning objectives

4(g)

4(h)

Understand that chlorophyll traps light

energy and converts it to chemical
energy for the formation of
carbohydrates and their subsequent
storage

Explain why most forms of life are

completely dependent on
photosynthesis

Suggested teaching activities

Learning resources

Explain the entry of carbon dioxide through pores (stomata) in the leaf
surface by diffusion and its subsequent diffusion through spaces between
mesophyll cells. CO2 then dissolves before entering the cells and diffusing
into chloroplasts.

See 4(i) below for resources to

demonstrate action of guard cells and
stomata. Resources to demonstrate
diffusion are referenced in Unit 1.

Chlorophyll absorbs the light energy and thus photosynthesis occurs

where chlorophyll is located in the chloroplasts. No details of lightdependent and independent reactions are required.
Glucose manufactured by photosynthesis may be converted to starch and
stored in the chloroplasts and/or converted to sucrose to be conducted to
other organs (via phloem) for storage as sucrose or as starch. Invite
learners to suggest examples of such storage organs.

Uses of glucose made in photosynthesis:

http://lgfl.skoool.co.uk/

Learners may prepare a temporary microscope slide using a thin scraping

of potato tissue stained with iodine solution to show the presence of starch
grains. Explain the storage of carbohydrate in the form of insoluble starch
in terms of the osmotic balance of cells.

Photomicrograph of starch grains:

www.microscopy-uk.org.uk/

A challenging activity is to present learners with the learning objective

and to ask them to collaborate with other learners to suggest explanations
for why this is so.
Explain that the carbohydrates (and the proteins subsequently produced
see 4(j)) are important components of their own diets manufactured by
plants. Fats and oils are also manufactured by plants. Learners may be
able to name common examples. Explain that humans require O2 to
respire and that they breathe out CO2 the exact reverse of
photosynthesis.

4(i)

Identify and label the cuticle, cellular

and tissue structure of a
dicotyledonous leaf, as seen in a
cross-section under a microscope, and
describe the significance of these
features in terms of function, i.e.

V1 3Y08

Using a projected photomicrograph or TS diagram of a leaf and identify

the main tissues - explaining the role of each part in photosynthesis.

Photomicrograph of leaf TS:

http://images.botany.org/

A basic activity is to supply learners with a large, clear, unlabelled drawing

of a leaf TS and, using the above resource, ask them to label their
diagrams. Include labels for xylem and phloem (see Unit 3) as well as for

Leaf TS diagram (labelled):

www.bbc.co.uk/

Cambridge O Level Biology (5090)

16

Learning objectives

distribution of chloroplasts
photosynthesis
stomata and mesophyll cells gas
exchange
vascular bundles transport

Suggested teaching activities

Learning resources

vascular bundle and describe the functions of the two separate tissues.

Leaf TS diagram (unlabelled)

www.ellenjmchenry.com/

A more challenging activity is for learners to draw a TS of the leaf from

their observation of a microscope slide and to annotate this with details of
the component structures.
Extend learners practical work using the measuring stomatal density
activity from the online resources list.

Measuring stomatal density:

www.saps.org.uk/

Explain the control of stoma size by water pressure within guard cells.
Demonstrate the opening and closing of stomata by using two balloons to
represent guard cells. Affixing a band of adhesive tape along one edge of
each balloon prior to their inflation models the change in cell shape on
becoming turgid.

Video clip of guard cells opening and

closing stomata:
www.youtube.com/
BIOSCOPE (2004) CD TS leaves of
Erica and privet
5090 past paper question:
Nov 2011 Paper 22 Q6

4(j)

Understand the effect of a lack of

nitrate and magnesium ions on plant
growth

Carbohydrate manufactured by photosynthesis is the molecule which acts

as the starting point for building other organic molecules. Plants must
absorb ions from the soil in order to make these molecules. Magnesium is
necessary for chlorophyll manufacture and nitrates for protein
manufacture. Without magnesium a plant cannot photosynthesise and
without proteins it cannot grow.

Uses of glucose made in photosynthesis:

http://lrrpublic.cli.det.nsw.edu.au/

Magnesium deficiency:
www.gardenersworld.com/

A basic activity is to use photographs to demonstrate plants grown under

these deficiencies alongside a control which does not lack the ions. Ask
learners to identify and account for the visible differences between the
plants shown.
A more challenging activity is for learners to grow plants in culture
solutions lacking magnesium or nitrates and to compare their growth after
several weeks against a plant grown in a control culture medium.
6(a)

Relate structure and functions of root

hair cells to their surface area and to
water and ion uptake

V1 3Y08

The importance of surface area, in particular of root hair cells for the
uptake of water and ions, has been covered in Unit 1. Learning objectives
4(f) and 4(j) above have also referred to their uptake. This learning

Cambridge O Level Biology (5090)

Root hair diagrams and photographs:

http://www.biologie.uni-hamburg.de/

17

Learning objectives

Suggested teaching activities

Learning resources

objective provides an opportunity for these facts previously taught to be

consolidated.

Uptake by root hairs:

http://lgfl.skoool.co.uk/
Textbooks:
Jones, M Unit 7 Transport in Flowering
Plants
Jones, G & Jones, M 7 Transport
Burton, I J Topic 8 Transport in
Flowering Plants

6(b)

6(c)

State that transpiration is the

evaporation of water at the surface of
the mesophyll cells followed by the
loss of water vapour from the leaves
through the stomata

Ensure that learners understand that evaporation has occurred first from
moist surfaces of mesophyll cells within the leaf prior to water vapour then
diffusing through the leaf spaces and out into the atmosphere down a
concentration gradient. Ensure also that there is no confusion between
guard cell and stoma(ta).

Describe:
how water vapour loss is related to cell
surfaces, air spaces and stomata

Explain that those conditions which speed up or slow down the

evaporation of water also speed up or slow down the rate of transpiration.
Increased light intensity speeds up transpiration by virtue of the fact that it
opens up the stomata to their fullest extent.

the effects of air currents (wind), and

the variation of temperature, humidity
and light intensity on transpiration rate

Learners may be provided with a diagram of a potometer set up to

investigate the rate of water loss/uptake. A basic activity is to ask learners
how the potometer may be used to investigate the loss/uptake of water.

how wilting occurs

A more challenging activity is for learners to write a step-by step plan of a

controlled investigation into how altering one condition affects the rate of
water loss/uptake.
Practical use of a potometer provides good visual support to this section;
however difficulty may be experienced in altering any of the variables
required. Graphs may be either provided to learners, or as a more
challenging activity they may draw their own from data provided, to show
the effect of each factor on the rate of water loss/uptake.

Basic transpiration animation:

http://extension.oregonstate.edu/

Detailed transpiration animation:

www.kscience.co.uk/

Use of a potometer:
www.biologydaily.com/
Potometer interactive activity:
www.sycd.co.uk/
Using a potometer to compare
transpiration rates:
www.saps.org.uk/

Past papers questions:

V1 3Y08

Cambridge O Level Biology (5090)

18

Learning objectives

6(d)

Investigate, using a suitable stain, the

pathway of water in a cut stem

Suggested teaching activities

Learning resources

Explain that water lost from a plant must be replaced from the soil. If the
rate of water loss exceeds its rate of uptake the plant will wilt (not wither).
Invite learners to describe and explain the appearance of a wilted plant.

Jun 2011
Paper 21 Q 2
Nov 2010 Paper 62 Q1

Learners will know that water travels in the xylem. This learning activity
will demonstrate the distribution of xylem tissue in a chosen stem. Though
not a stem, a stick of celery is a suitable material for this demonstration,
however any plant with a relatively colourless and fleshy stem is likely to
be satisfactory.

Movement of dye through xylem of celery

activity:
www.york.ac.uk/
5090 past paper question:
Jun 2011 Paper 22 Q6

Learners should cut the stem cleanly and place the cut end in a solution of
a suitable stain (food dye is inexpensive and works well). Results can
often be seen in 10 to 15 minutes when a further section is taken from the
stem at a position just above the level of the solution. Learners may then
make a labelled drawing of their observations. The activity may be
extended to compare and explain the rate of movement in a leafy and
non-leafy stem.
6(e)

Explain the movement of water

through the stem in terms of
transpiration pull

Explain that the evaporation of water from mesophyll cells increases the
concentration in the sap vacuole of those cells. Osmosis then draws more
water up the xylem to replace the water lost. Dissolved in that water are
ions which have been absorbed by the root hairs.

Resources for illustrating the movement

of water during the transpiration stream:
Basic transpiration animation:
http://extension.oregonstate.edu/
Detailed transpiration animation:
www.kscience.co.uk/

6(f)

Identify the positions of xylem and

phloem tissues as seen in transverse
sections (TS) of unthickened,
herbaceous, dicotyledonous roots,
stems and leaves

Use projected photomicrographs then diagrams to demonstrate the

position and appearance of xylem and phloem in roots and stems (leaves
have already been considered in 4(i) above).

BIOSCOPE (2004) CD: TS and LS of

Ranunculus stem and root

Use a transparency to project labelled diagrams of the position of the

xylem and phloem in roots and stems. Supply learners with blank copies
of the diagrams to label.
A more challenging activity is for learners to draw and label their own
diagrams from observations of TS microscope slides of dicotyledonous
roots, stems and leaves.

V1 3Y08

Cambridge O Level Biology (5090)

19

Learning objectives

Suggested teaching activities

Learning resources

An extension activity in which learners consider the effects of 'ringing' a

tree can help to bring together knowledge of stem structure and function.
Small mammals gnaw the bark and destroy the phloem that is in the inner
bark region. If the ring is cut below the leaves, then all the cells beneath
the ring are deprived of products of photosynthesis from the leaves, and
eventually die.
6(g)

State the functions of xylem and

phloem

V1 3Y08

Annotate the diagrams from 6(f) above to indicate that phloem conducts
SUCROSE (not glucose) and amino acids in solution and the xylem
carries water and ions (dissolved salts).

Cambridge O Level Biology (5090)

20

Scheme of work Cambridge O Level Biology (5090)

Unit 3: Animal nutrition
Recommended prior knowledge
Learners need to know of the existence of chemical elements, particularly of carbon, oxygen, hydrogen and nitrogen, also that chemical energy is contained within the
larger organic molecules. Knowledge of enzymes and enzyme action is necessary (Unit 1) as well as a very simple understanding of the circulatory system. Otherwise,
this unit could be used as a starting point for the course with the above requirements being dealt with as they arise in the learning objectives.
Context
This unit provides the underlying biochemical knowledge essential for studying almost all of the other units in the course.
Outline
The unit begins with a study of the three major classes of organic nutrients and their food tests. Diet and its importance are considered, as well as the processing of
dietary intake within the body. The action of specific enzymes is considered and the unit ends with a link to Unit 5 with a consideration of the role of the liver.
Learning objectives

Suggested teaching activities

Learning resources
5090 past question papers are
available at: http://teachers.cie.org.uk

Candidates should be able to:

5(a)

List the chemical elements that make up

carbohydrates, fats and proteins

That carbohydrates and fats contain carbon, hydrogen and oxygen only
(but in different proportions) and that proteins contain the same three
elements plus nitrogen can be illustrated using a collection of four different
shapes cut from paper or thin card and moved around on an OHP under
food-group headings. Explain that hydrate relates to water and
carbohydrates always contain H and O in the same ratio as in water.

Nutrition and food groups:

www.s-cool.co.uk/
http://purchon.com/
Textbooks:
Burton, I J Topic 5 Nutrition
Jones, G & Jones, M 4 How Animals
Feed
Jones, M Unit 5 Animal Nutrition
Diet

V1 3Y08

Cambridge O Level Biology (5090)

21

Learning objectives

Suggested teaching activities

Learning resources

5(b)

Learners perform the tests on prepared solutions of starch, glucose and

egg albumen and cooking oil. They should carry out a test in each case on
pure water as a control. Observations and conclusions to be recorded in a
table.

Food tests practical procedure:

www.biotopics.co.uk/

Describe tests for starch (iodine in

potassium iodide solution), reducing
sugars (Benedicts solution), protein
(biuret test) and fats (ethanol emulsion
test)

A more challenging activity is for learners to identify the components of

an unknown mixture of food molecules. Extend the practical to test
common foodstuffs making predictions about the presence or absence
of components prior to testing.

5(c)

5(d)

5(e)

List the principal sources of, and

describe the dietary importance of,
carbohydrates, fats, proteins, vitamins
(C and D only), mineral salts (calcium
and iron only), fibre (roughage) and
water

Name the diseases and describe the

symptoms resulting from deficiencies of
vitamin C (scurvy), vitamin D (rickets),
mineral salts, calcium (rickets) and iron
(anaemia)

Understand the concept of a balanced

diet

V1 3Y08

Food tests practical animation:

http://lgfl.skoool.co.uk/
5090 past paper questions:
Nov 2011 Paper 31 Q2
Nov 2011 Paper 32 Q2

Consider the importance of the different chemical constituents of a diet

before considering their sources. Use the online resources listed to
research the components and to compare how the principal sources of
each differ in different areas of the world.

Vitamins:
http://kidshealth.org/

Learners may present this information in the form of a three column table
showing components, sources and dietary sources.

Minerals:
http://kidshealth.org/

Food packets provide a useful source of stimulus material. Learners may

be asked to bring in a range of food packaging and to discuss the
significance of the data displayed regarding their nutritional content.

http://kidshealth.org/teen/food_fitness/

Descriptions of the deficiency diseases resulting from a lack of vitamins C

and D should be supported if possible with pictures. The need for calcium
in the development of strong bones and teeth should be mentioned. The
role of iron in the manufacture of haemoglobin for oxygen transport should
also be included. Learners may research information on the vitamins and
minerals listed and present their findings either in a table or in the form of
an illustrated poster.

Deficiency diseases:
http://lgfl.skoool.co.uk/

Stress the importance of a diet containing the correct proportions of each

constituent to satisfy the bodys needs. Too little or too much of any one or
more constituents can be harmful - see 5(e), (f) and (g).
A possible introduction to the topic is to show learners pictures of people
whose diet is unbalanced (including obese and starving people) and to
ask them what the people have in common.
The online resources and video clips may then be used to explain the

Dietary food groups activity:

www.footprints-science.co.uk/

Cambridge O Level Biology (5090)

http://kidshealth.org/

Scurvy and Rickets:

www.nhs.uk/conditions/
www.nhs.uk/conditions/Scurvy/

Balanced diet video clips:

www.bbc.co.uk/
www.bbc.co.uk/learningzone/

22

Learning objectives

Suggested teaching activities

Learning resources

concept of a balanced diet.

5(f)

Explain why diet, especially energy

intake, should be related to age, sex and
activity of an individual

Present and analyse data showing the energy requirements for sedentary
and physical life styles together with those of people of different ages.
Consider how diet, other than energy, may differ at different stages of a
persons life. Cross reference 16(y) in Unit 8.
Learners should be aware of the main sources of each type of nutrient in
their own country, but also be prepared to consider how diets differ in
other parts of the world. The science across the world online resource
may be used to facilitate this appreciation.
Learners may keep a record of the food they eat during a short period of
time and then consider whether they are obtaining the nutrients they need.
Their diet could be analysed using printed food tables or the national
nutrient database online resource.

Energy requirement data table:

www.nhlbi.nih.gov/
Interactive balanced diet:
www.abpischools.org.uk/
Science Across the World:
www.nationalstemcentre.org.uk/
National nutrient database:
http://www.nal.usda.gov/
Practical Biology - Energy in food:
www.practicalbiology.org/

A more challenging activity is for learners to practically investigate and

compare the amount of energy in a variety of foods. Learners basic
mathematical and skills will be utilised in this activity. Extend the practical
work by asking learners to present their numerical data in a variety of
formats including tables and suitable graphs.

5090 past paper question:

Jun 2011 Paper 22 Q2

5(g)

State the effects of malnutrition in

relation to starvation, heart disease,
constipation and obesity

Link to work on the causes of famine in 5(h) but also use this objective to
illustrate that eating too much of a food group over a prolonged period is
also a form of malnutrition. Discuss the growing problem in developed
countries of obesity leading to heart disease.

World Health Org. obesity website:

www.who.int/topics/obesity/en/

5(h)

Discuss the problems that contribute to

famine (unequal distribution of food,
drought and flooding, increasing
population)

Use a stimulus picture to initiate a group brainstorm where learners list all
the factors they can think of which contribute to famine. These can then
be collected, compared and discussed further.

Famine stimulus picture:

http://i207.photobucket.com/

Extend learners research skills by asking them to collect information on

famine and the problems contributing to its cause from newspaper and/or
television sources prior to teaching this topic.

The problems of feeding the world's

growing population with links to many
sites:
www.nationalacademies.org/webextra/c
rops/

Extend learners thinking by asking them to consider whether new

technologies, such as the development of genetically modified varieties of

V1 3Y08

Cambridge O Level Biology (5090)

23

Learning objectives

Suggested teaching activities

Learning resources

crops, are likely to improve the situation or exacerbate it. The concept of
food miles may also be considered.
5(i)

Identify the main regions of the

alimentary canal and the associated
organs: mouth (buccal) cavity, salivary
glands, oesophagus, stomach,
duodenum, pancreas, gall bladder, liver,
ileum, colon, rectum and anus

Provide a labelled diagram of the appropriate components of the

alimentary canal. Avoid providing more labels than the syllabus requires.

Regions of the digestive system:

www.bbc.co.uk/schools/

Write a flow chart to show the order in which food travels through the
labelled regions and list separately the associated organs through which
food does not travel.

Digestive system and digestion

relevant to several learning objectives.
www.abpischools.org.uk/

The suggested online resources provide good source material in the form
of diagrams and animations to support these activities.

Textbooks:
Jones, M Unit 6 Animal Nutrition
Digestion
Burton, I J Topic 7 Animal Nutrition

5(j)

Describe the main functions of these

parts in relation to ingestion, digestion,
absorption, assimilation and egestion of
food, as appropriate

The terms ingestion and absorption are usually easily understood. Stress
that only certain large molecules are digested (in order to be absorbed).
Assimilation is less easily understood and should be described as the
incorporation of absorbed chemicals into the structure of an organism.
Egestion and excretion are often confused by learners, so careful
explanation will be required.

See suggested resources above.

Add annotations to the labelled diagram provided in 5(i) to show which

function(s) occur(s) in each region labelled.

5(k)

Identify the different types of human

teeth and describe their structure and
functions

V1 3Y08

The need for digestion to take place before absorption occurs may be
shown by using Visking tubing (to represent the alimentary canal)
containing a mixture of glucose, starch and water. This is placed in a
beaker of water (to represent blood). Ask learners to make predictions
about the results of tests for starch and glucose performed on the
contents of the tube and of the beaker before and after leaving for a
period of time to allow the glucose to diffuse across the tubing

Visking tubing model gut demo:

www.nuffieldfoundation.org/

Include reference to milk and wisdom teeth. Cutting and grinding (as
appropriate) should be used in place of chewing. Use a model tooth to
show internal structure. Provide learners with diagrams of a tooth in

Types of teeth:
www.crickweb.co.uk/

Cambridge O Level Biology (5090)

24

Learning objectives

Suggested teaching activities

Learning resources

longitudinal section (LS) and of a dental arcade.

Internal tooth anatomy:

www.enchantedlearning.com/

Learners should label the structures shown on a longitudinal section (LS)

of a tooth and name and label the functions of the different teeth in a lower
or upper jaw.
5(l)

State the causes of dental decay and

describe the proper care of teeth

Stress that sugar left on teeth, particularly whilst asleep, attracts bacteria
and that it is the acid excreted by these bacteria as they feed on the sugar
which dissolves the enamel.
Use commercially available disclosing tablets to reveal the plaque layer
on learners teeth. Discuss the alkaline nature of toothpaste, and of saliva
released when chewing sugar free gum, in neutralising the acid produced.

5(m)

Describe peristalsis

Use the tooth decay animation to illustrate the process to learners and
then ask them to produce a written account of the process and how it may
be prevented.

Tooth decay animation:

www.mchoralhealth.org/

A bead in a length of rubber tubing illustrates the action. Reference should

be made to food being pushed along the entire length of the gut by
waves of contraction of circular muscles and of the antagonistic effect of
the longitudinal muscles.

Digestion, including peristalsis diagram

and animation:
www.passmyexams.co.uk/

Use the online resource suggested to show learners a video clip of

peristalsis occurring in a patient.

Endoscopic peristalsis video:

www.youtube.com/

Learners should describe the muscular action involved in peristalsis and

explain its importance.
5(n)

Explain why most foods must be

digested

Also see 5(j). Only small molecules can pass through the membranes of
the cells lining the gut to be absorbed into the body. Until then, even when
in the gut, they are still outside the body. Starch, proteins and fats are too
large to be absorbed and must be broken down into the smallest
constituent parts.
Shapes cut from thin card and projected on a PowerPoint slide or
overhead projector can illustrate effectively how starch is constructed from
a string of monosaccharide units, proteins from amino acids and fats from

V1 3Y08

Cambridge O Level Biology (5090)

Macromolecules and end prods:

www.passmyexams.co.uk/

25

Learning objectives

Suggested teaching activities

Learning resources

fatty acids and glycerol.

5(o)

Describe digestion in the alimentary

canal and the functions of a typical
amylase, protease and lipase, listing the
substrates and end products

Where each molecule is dismantled may be related to a specific region of

the alimentary canal and to a specific enzyme (and optimum pH). When
food arrives in the ileum, only the end products of digestion are present
(together with those chemicals that are not broken down, either because
they are already small enough for absorption or because no enzymes are
present for their breakdown). The role of bile in emulsifying fats should be
included.

Digestion diagrams and explanations:

www.bbc.co.uk/schools/

The effect of bile as an emulsifier may be demonstrated by adding

washing up detergent (to represent bile) to cooking oil (to represent lipids
consumed) added to water and stirred. Learners may then draw diagrams
to represent the process of bile emulsifying the fat droplets to increase
their surface area over which lipase may act.

Digestion animated video:

www.bbc.co.uk/

Refer back to the diagram provided in 5(i) and explain how each region
and organ achieves the breakdown demonstrated in 5(n).

www.bbc.co.uk/

A more challenging activity is for learners to answer a question such as

describe fully the digestion of a potato fried in oil to test their
understanding and sequencing of the important facts relating to the
digestion of multiple food chemicals.
5(p)

Describe the structure of a villus,

including the roles of capillaries and
lacteals

All food substances entering the body are absorbed by villi. Refer to the
large surface area of each villus and of villi collectively. Display a large
annotated diagram to show villus structure in LS. All absorbed substances
pass into the blood capillaries, with the exception of the digested fats
which pass into the lacteals.

www.bbc.co.uk/schools/digestion3.shtm
l
www.s-cool.co.uk/

Digestion video clips:

www.bbc.co.uk/

5090 past paper questions:

Jun 2011 Paper 21 Q5
Jun 2010 Paper 22 Q8

Photomicrograph of villi:
http://missinglink.ucsf.edu/
Labelled diagram of villus:
www.bbc.co.uk/scotland/

Make a large, labelled and annotated drawing of a villus.

5(q)

Describe the significance of villi in

increasing the internal surface area

V1 3Y08

As 5(p):
All food substances entering the body are absorbed by villi. Refer to the
large surface area of each villus and of villi collectively. Display a large
annotated diagram to show villus structure in LS. All absorbed substances
pass into the blood capillaries, with the exception of the digested fats
which pass into the lacteals.

Cambridge O Level Biology (5090)

As above:
Photomicrograph of villi:
http://missinglink.ucsf.edu/
Labelled diagram of villus:
www.bbc.co.uk/scotland/

26

Learning objectives

Suggested teaching activities

Learning resources

Make a large, labelled and annotated drawing of a villus.

5(r)

State the function of the hepatic portal

vein as the route taken by most of the
food absorbed from the small intestine

5(s)

State:
that large molecules are
synthesised from smaller basic
units - glycogen from glucose,
proteins from amino acids, lipids
(fats and oils) from
glycerol and fatty acids

Explain that lacteals unite to join the lymph system, which feeds into the
circulatory system and by-passes the liver. Blood capillaries link directly
with the liver via the hepatic portal vein.

The breakdown of large molecules to small ones has already been

considered. The reverse of this is a part of the process of assimilation.
Stress that glucose in animals is built up into glycogen rather than starch.
Simple modelling kits can be used to illustrate the concept of small
molecules joining together to make larger ones.

the role of the liver in metabolism

of glucose and amino acids

Conversion of glucose into glycogen and its storage occur in the liver.
Refer to 11(j) and (k) in Unit 5 for details.

the role of fat as a storage

substance

Fat is a high-energy, insulating storage substance. It is stored in the

dermis and round kidneys. It is not considered to be stored around the
heart.

that the formation of urea and the

breakdown of alcohol occur in the
liver

5090 past paper question:

Jun 2011 Paper 21 Q6a

The breakdown of excess amino acids into a carbohydrate (stored as

glycogen) and the excretory product urea in the liver should be mentioned.
As a part of its role in removing poisons the liver also breaks down
alcohol.
An extension activity to highlight the importance of the liver is to ask
learners to research and present information on the causes and effects of
liver failure.

V1 3Y08

Cambridge O Level Biology (5090)

27

Scheme of work Cambridge O Level Biology (5090)

Unit 4: Human transport and respiration
Recommended prior knowledge
The first part of this unit stands very much alone and can be studied in isolation, although knowledge of the substances absorbed into the blood from the small intestine
would be useful. The respiration section of the unit would certainly benefit from a prior knowledge of chemical molecules and of energy (see Units 2 and 3) and of active
transport (Unit 1).
Context
Since all characteristics of living organisms are heavily dependent on the energy released during respiration, this unit provides essential knowledge for the understanding
of most of the other units.
Outline
The structure and function of the heart and the circulatory system are considered together with coronary disease. The structure and function of blood and its component
parts are also studied. Aerobic and anaerobic respiration are covered as well as the organs and structures involved in gaseous exchange. The unit generates a varied
assortment of practical investigations.
Learning objectives

Suggested teaching activities

Learning resources
5090 past question papers are
available at http://:teachers.cie.org.uk

Candidates should be able to:

7(a)

Describe the circulatory system as a

system of tubes with a pump and
valves to ensure one-way flow of
blood

The name of the pump (the heart) and of the three different types of blood
vessel should be mentioned. It is possible to demonstrate the one-way
action of valves in the vein running along the back of the wrist or fore-arm
by performing a similar procedure to the English scientist William Harvey in
1628.

William Harveys experiment:

www.princeton.edu/
Heart and circulation:
www.abpischools.org.uk/
Video clips:
www.bbc.co.uk/human-circulation

V1 3Y08

Cambridge O Level Biology (5090)

28

Learning objectives

Suggested teaching activities

Learning resources
Textbooks:
Burton, I J Topic 9 Transport in
Human Beings
Jones, G & Jones, M 7 Transport
Jones, M Unit 8 Transport in Humans

7(b)

Describe the double circulation in

terms of a low pressure circulation to
the lungs and a high pressure
circulation to the body tissues and
relate these differences to the
different functions of the two circuits

Explain that blood leaves the heart in arteries, returns in veins, and that
arteries are joined to veins by capillaries. Since the lungs are close to the
heart, and at the same level as the heart, the pressure needed to send
blood to them is lower. Label and shade (to show oxygenated and
deoxygenated blood) diagrams of the double circulation.

Double circulation animations:

www.bbc.co.uk/circulatorysys

7(c)

Name the main blood vessels to and

from the heart, lungs, liver and
kidneys

A simplified, labelled, demonstration diagram of only those blood vessels

specified may be explained to learners and then a similar but unlabelled
diagram provided for learners to label.

Simplified vessel diagram:

www.ringwoodbiology.co.uk/

7(d)

Describe the structure and function of

the heart in terms of muscular
contraction and the working of valves

A labelled demonstration diagram may be used to provide the correct

terminology for the structures of the heart and to explain the heart cycle and
the action of valves. Stress that both atria contract together, followed by
both ventricles rather than the right side contracting first to send blood to
the lungs, followed by the left side to send blood to rest of the body. As
above, an unlabelled diagram should be provided for learners to label.

Circulatory system animations:

http://apan.net/

A demonstration dissection of a heart may be carried out, although be alert

to the possible sensibilities of individual learners.

7(e)

Compare the structure and function

of arteries, veins and capillaries

Transverse section (TS) drawings of all three vessels should be supplied

together with a longitudinal section (LS) of a vein to show semi-lunar valves.
Annotations on the diagrams can be used to link structure with function.
Compare the nature of blood flow in each.
Learners may complete a table to compare the structure and function of the
three types of blood vessel.

V1 3Y08

Cambridge O Level Biology (5090)

Heart structure diagrams:

www.bbc.co.uk/circulatorysys2
Practical Biology Heart dissection:
www.practicalbiology.org/

Blood vessel structure and function:

www.s-cool.co.uk/bloodvessels
Artery and vein (TS):
www.bioclix.org/
Blood vessel animations:

29

Learning objectives

Suggested teaching activities

Learning resources
www.medmovie.com/

Ask learners to use their knowledge to identify the type of blood vessel
labelled A and B in the online resource and to write a paragraph to explain
how their structure and functions can be compared.

7(f)

Investigate and state the effect of

physical activity on pulse rate

BIOSCOPE CD (2004)
TS of artery and of vein

Use the blood vessel animation online resource to show the flow of blood
through vessels under a range of conditions. Note the action of valves in
veins.

5090 past paper question:

Nov 2011 Paper 22 Q7

Learners should locate an artery (e.g. at their wrist or at the side of the
neck) and count and record the rate of the pulse at rest. The number of
beats per 15 sec should be recorded and multiplied by four to give beats
per minute. Learners should work in pairs one as the researcher and one
as the subject, who takes two minutes brisk exercise. Immediately
afterwards, the researcher takes the pulse rate for 15 sec every minute until
the rate returns to normal.

Practical Biology Control of heart rate:

www.practicalbiology.org/

Graphs may be drawn of rate (beats per minute) against time. Data for the
whole class may be pooled and compared if they all perform exactly the
same exercise and the investigation extended as an opportunity to discuss
control of variables.
7(g)

Describe coronary heart disease in

terms of the occlusion of coronary
arteries and state the possible
causes (diet, stress and smoking)
and preventive measures

This objective links with Unit 3. Saturated fats and cholesterol should be
mentioned as being constituents of atheroma. The need for exercise should
be stressed as well as other precautions, especially if there is a family
history of heart disease

CHD website including animation:

http://hcd2.bupa.co.uk/heart_disease

Learners may write a commentary to the suggested online resource to list

the steps in development of atheroma. A list of the possible causes and
preventative measures, in the form of a table, may accompany the diagram.
7(h)

Identify red and white blood cells as

seen under the light microscope on
prepared slides, and in diagrams and
photomicrographs

A basic activity is for learners to be shown diagrams and photomicrographs

of blood cells. Learners should note the paler colour of red blood cells
towards their centres, the different comparative sizes and numbers of red
and white cells, and that there are different types of white cell (their different
names are not required). Note that the colours of the cells are as seen after
staining and are not their natural colours.

Blood cell photomicrograph:

http://t0.gstatic.com/
Images of blood cells:
www.exploratorium.edu/=
BIOSCOPE CD (2004)

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Cambridge O Level Biology (5090)

30

Learning objectives

7(i)

List the components of blood as red

blood cells, white blood cells,
platelets and plasma

7(j)

State the functions of blood:

red blood cells haemoglobin and
oxygen transport
white blood cells phagocytosis,
antibody formation and tissue
rejection
platelets fibrinogen to fibrin,
causing clotting
plasma transport of blood cells,
ions, soluble food substances,
hormones, carbon dioxide, urea,
vitamins and plasma proteins.

7(k)

Describe the transfer of materials

between capillaries and tissue fluid

Suggested teaching activities

Learning resources

A more challenging activity is for learners to use microscopes to view

prepared slides of blood at high power. Learners may be asked to draw the
cells observed and to annotate their diagrams to describe the structure and
basic functions of the cells drawn.

Human Blood

Constituents of blood:
www.pennmedicine.org/

Learners may prepare a table to show the name and functions of each type
of blood cell. The table may be extended to show a diagram of cells seen in
7(h) above.
The ability of haemoglobin to absorb and to release oxygen should be
mentioned. Link to 5(d) Unit 3 - anaemia.
Learners may write a commentary to the online resource animations. A
more challenging activity is to invite learners to suggest why transplants
are likely to be more successful between closely related people.

Action of white blood cells:

www.bbc.co.uk/schools/
Phagocytosis animation:
www.edumedia-sciences.com/
Blood clotting animation:
www.footprints-science.co.uk/
5090 past paper question:
Jun 2010 Paper 22 Q8

Fibrinogen should be introduced as a plasma protein. The role of the

clotting process and formation of a scab in preventing entry of pathogens
should be included. Link to 5(d) in Unit 3 - calcium.
Learners may watch the suggested online animation and write an
accompanying commentary. As an extension activity learners may
research the disease haemophilia.
Capillaries may be thought of as leaky, but their walls will not allow large
molecules to pass. Plasma proteins are too large to do so, as are blood
cells with the exception of some white blood cells which are able to change
shape to squeeze through and reach a site of infection. This description will
allow learners to differentiate between plasma and tissue fluid.
Stress the two-way movement of materials with metabolic products able
to pass from cells into capillaries. Cross-reference 5(p) in Unit 3 and 8(k) in
Unit 4.

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Cambridge O Level Biology (5090)

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Learning objectives

Suggested teaching activities

Learning resources

8(a)

It is essential at this stage to differentiate between breathing and

respiration. It should be made clear that respiration is a chemical reaction
occurring in all living cells with the sole purpose of releasing energy. Also
stress that energy is not needed for respiration and that respiration does
NOT create or produce energy. Note that the definition allows for
respiratory substrates other than glucose, although glucose is the only one
required by the syllabus.

Aerobic and anaerobic respiration:

www.s-cool.co.uk/summary

Respiration may be compared with combustion the equation is the same,

but respiration occurs in a series of small reactions that do not suddenly
release large amounts of heat energy. Link to 3(d) in Unit 1 enzymes.

Introduction to respiration:
www.biotopics.co.uk/

Define respiration as the release of

energy from food substances in all
living cells

If not already carried out in Unit 3, learners may practically investigate and
compare the amount of energy in a variety of foods. Learners basic
mathematical and skills will be utilised in this activity. Extend the practical
work by asking learners to present their numerical data in a variety of
formats including tables and suitable graphs. The activity may be extended
by considering how use of a calorimeter provides a more accurate method
of determining energy content.

Note: this resource is relevant to many

of the subsequent learning objectives in
this unit.

Textbooks:
Jones, M Unit 9 Respiration
Ian J. Burton Topic 10 Respiration
Jones, G & Jones, M 6 Respiration
5090 past paper question:
Nov 2011 Paper 32 Q2(c)

An extension activity is to demonstrate the release of heat energy by

germinating seeds. See online resource.
8(b)

Define aerobic respiration as the

release of a relatively large amount
of energy by the breakdown of food
substances in the presence of
oxygen

Learners should realise that during this process the glucose is completely
broken down to its constituent molecules, releasing all of the energy
absorbed in building the molecule.

8(c)

State the equation (in words or

symbols) for aerobic respiration

In Unit 2 learners have learnt the equation for photosynthesis and that the
process is the reverse of respiration. Again, a word equation is acceptable,
but if symbols are used the equation must balance (it is acceptable to add
+ energy released on the right hand side).

8(d)

Name and state the uses of energy in

the body of humans: muscle
contraction, protein synthesis, cell

This objective allows for the introduction of the concept of energy being
required to build large molecules other than glucose or starch. Two further
types of energy are also introduced heat energy and electrical energy, to

V1 3Y08

Introduction to respiration:
www.biotopics.co.uk/humans/respro.ht
ml

An extension activity is to use a respirometer to demonstrate the uptake of

oxygen by living tissue. See online resource.

Cambridge O Level Biology (5090)

32

Learning objectives
division, active transport, growth, the
passage of nerve impulses and the
maintenance of a constant body
temperature

8(e)

Define anaerobic respiration as the

release of a relatively small amount
of energy by the breakdown of food
substances in the absence of oxygen

Suggested teaching activities

Learning resources

add to light and chemical energy so far considered in Unit 2.

Learners may produce a spider diagram to state the uses of energy and
may illustrate their diagram with hand-drawn or printed pictures and/or
further annotations.

This is likely to be a new concept for learners. It may be explained that in

the absence of oxygen, the respiratory substrate is not completely broken
down into its constituent molecules. Some chemical energy therefore
remains in the molecules produced in the reaction, leaving less to be
released than in aerobic respiration.
Anaerobic respiration can be demonstrated using a suspension of yeast in
boiled (to remove dissolved O2) water. The CO2 released can be detected
by being bubbled through lime water in a test tube using a delivery tube.
This activity may alternatively be carried out when delivering learning
objective 14(c) in Unit 6.

8(f)

State the equation (in words or

symbols) for anaerobic respiration in
humans and in yeast

Two forms of anaerobic respiration are relevant to the syllabus. Both should
be given with a clear explanation that one form is encountered in
fermentation (Unit 6) and the other in muscle action. Word equations are
likely to be more easily accessible to learners at this level.

8(g)

Describe the effect of lactic acid

production in muscles during
exercise

Ask learners to raise their arm and to open and close their fist in quick
succession for as long as possible. The resulting discomfort is a result of
lactic acid build up in the muscles. Whilst discussing the concept with
learners, sufficient time will elapse for the discomfort to subside a result of
the lactic acid being broken down into harmful carbon dioxide and water.
Use the stimulus photo of a runner with muscle cramp to elucidate ideas.

Marathon runner stimulus photo:

http://gobblegreen.com/

This can be related to the build-up of lactic acid during exercise. Cramp
often strikes after exercise has finished - a result of the circulation not being
able to remove the lactic acid quickly enough from the muscles - refer to
7(k).
8(h)

Know the percentages of gases in

atmospheric air and investigate and

V1 3Y08

A table of differences with approximate percentages should be given.

Learners may use this data to plot pie charts of gas composition and to

Cambridge O Level Biology (5090)

Composition of air table:

www.yteach.co.uk/

33

Learning objectives
state the differences between
inspired and expired air

Suggested teaching activities

Learning resources

produce written explanations for the similarities and differences apparent.

The table above should be supported by a practical investigation of the
comparative amounts of CO2 and water vapour in air, and of differences in
temperature.

Huff-puff apparatus:
www.chemistrydaily.com/

Learners may breathe out through limewater indicator to show presence of

CO2 in exhaled air. The demonstration may be extended to the huff-puff
apparatus to show more CO2 is present in exhaled than inhaled air.
Breathing into a test-tube of water at laboratory temperature for several
minutes (to demonstrate temperature of expired air) and onto dried cobalt
chloride paper (to show presence of moisture) may be suitable
investigations depending on ambient temperature and humidity.
8(i)

Investigate and state the effect of

physical activity on rate and depth of
breathing

Learners will be aware that they breathe more deeply after exercise. This
knowledge should be supported with an illustrative graph (which would also
show the change in rate of breathing). A spirometer, if available, may be
used to generate such a graph both before and after exercise.
Working in pairs, with one learner as the subject, breathing rates before and
after exercise may be measured (using the count for 15 sec then multiply
by 4 method repeated for 10 minutes after the exercise).
Graphs may be drawn of the results and compared with those obtained in
7(f) above.

Using a spirometer:
www.nuffieldfoundation.org/
Spirometer trace before and after
exercise:
www.brianmac.co.uk/

Extend learners practical skills by asking them to plan their own controlled
investigation to compare activities such as walking, skipping, running or
hopping with definite constant variables of time/distance.
A more challenging activity is for learners to explain the results of their
investigation using their knowledge of aerobic and anaerobic respiration.
8(j)

Identify on diagrams and name the

larynx, trachea, bronchi, bronchioles,
alveoli and associated capillaries

V1 3Y08

A labelled transparency or diagram of the contents of the thorax could be

shown and described to the learners. Include only the labels specified (plus
the diaphragm, ribs and intercostals muscles covered later). Supply
learners with an unlabelled version for them to label.

Cambridge O Level Biology (5090)

Thorax labelled diagram:

www.homebusinessandfamilylife.com/

34

Learning objectives

Suggested teaching activities

Learning resources

8(k)

Draw attention to the small size, large number and large surface area of the
alveoli. The thinness of the alveoli walls, their moist coating and the short
distance between the air and the extensive networks of capillaries should
also be included.

Gas exchange animation:

www.bbc.co.uk/respiratorysys3

State the characteristics of, and

describe the role of, the exchange
surface of the alveoli in gas
exchange

BIOSCOPE CD (2004)
Lung (showing alveoli)

Provide learners with an unlabelled diagram showing the alveolar wall

surrounded by a blood capillary. Ask learners to add labels to show the
direction that gases move by diffusion during gas exchange. Learners may
then annotate the diagram to describe the characteristics of the exchange
surface.
Learners may watch the animation from the online resource and then write
a commentary to describe the process of gas exchange.
8(l)

Describe the role of cilia, diaphragm,

ribs and intercostal muscles (external
and internal) in breathing

Ensure that learners do not believe cilia to be hairs that filter the passing air.

Inhalation and exhalation:

www.bbc.co.uk/respiratorysys1

Consider the mechanism by which these components result in altering the

volume and pressure in the thorax.

Learner-constructed model:
www.nuffieldfoundation.org/

A basic activity is to show learners balloons attached to a glass tube in an

air-tight bell jar with a rubber sheet stretched across its base to demonstrate
the principles involved. Ask learners to list ways in which the demonstration
does not accurately reflect the process of breathing.

Measuring lung capacity:

www.biologycorner.com/

A more challenging activity is for learners to construct similar models see

online resource.
Learners may use the method described in the online resource to simply
measure their own lung capacity.

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Cambridge O Level Biology (5090)

35

Scheme of work Cambridge O Level Biology (5090)

Unit 5: Coordination, response, movement and homeostasis
Recommended prior knowledge
Some knowledge of cells, blood and the circulatory system, osmosis and enzymes (particularly the effect of temperature on enzyme activity) would be helpful. A basic
understanding of the behaviour of light rays as they pass through lenses would be useful, though not essential.
Context
This unit builds on the idea that all units so far studied do not describe activities which operate in isolation within the body. All processes are interlinked to maximise the
survival and success of the organism.
Outline
Waste products from metabolism must not be allowed to accumulate within a body. Their removal is linked to the maintenance of a constant internal environment. In the
unit, the removal of carbon dioxide is considered as well as a simple treatment of the structure of the excretory system. The function of the kidney and of the artificial
kidney is given basic coverage and the homeostasis theme is continued with skin structure, temperature regulation and control by negative feedback. Nervous and
hormonal control is studied in relation to co-ordination, with reflex actions being amplified by a wider consideration of eye structure and the antagonistic arrangement of
muscles in the arm.
Learning objectives

Suggested teaching activities

Learning resources
Past papers available at
http://teachers.cie.org.uk

Candidates should be able to:

9(a)

Define excretion as the removal of

toxic materials and the waste
products of metabolism from
organisms

Teachers should be aware that many learners hold an inaccurate belief that
excretion is the correct term for defecation.

Textbooks:
Jones, G & Jones, M 10
Homeostasis and Excretion
Jones, M Unit 10 Excretion
Burton, I J Topic 12 Excretion

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Cambridge O Level Biology (5090)

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Learning objectives

Suggested teaching activities

9(b)

Describe the removal of carbon

dioxide from the lungs

This objective links excretion with respiration considered in Unit 4 and will
already have been described when considering gaseous exchange and
exhalation.

9(c)

Identify on diagrams and name the

kidneys, ureters, bladder, urethra,
and state the function of each (the
function of the kidney should be
described simply as removing urea
and excess salts and water from the
blood. Details of kidney structure and
nephron are not required)

Note that ureter and urethra must be spelt correctly. Stress that it is excess
water which is removed and refer to this helping to maintain the blood at a
constant concentration.

Describe dialysis in kidney machines

as the diffusion of waste products
and salts (small molecules) through a
membrane; large molecules (e.g.
protein) remain in the blood

A simple labelled diagram of a kidney dialysis machine should be provided.

9(d)

A diagram identifying the structures may be shown to learners who may then
label their own copy.
Learners may add annotations to their diagram to describe the function of each
labelled component.

Use the suggested online animation to demonstrate the movement of

substances across the dialysis membrane and to show that the content and
concentration of the dialysis fluid controls which substances leave the blood.
Learners may then write a summary of how the structure of the dialysis machine
is related to its function.
Submerge lengths of Visking tubing, tightly tied at both ends, in distilled water.
One tube should contain a solution of egg albumen (use dried albumen to make
the solution) and the other a solution of glucose. After 30 minutes test the
distilled water for the presence of protein and reducing sugar.

Learning resources

Labelled urinary tract diagram:

www.enchantedlearning.com/
Unlabelled urinary tract diagram:
www.enchantedlearning.com/
5090 past paper question:
Nov 2011 Paper 21 Q8

Dialysis machine diagram:

www.goldiesroom.org/
Dialysis membrane animation:
http://healthsciences.merlot.org/
Revision kidney failure:
www.s-cool.co.uk/kidney-failure
5090 past paper question:
Jun 2011 Paper 22 Q7

As learners will have met Visking tubing as a partially permeable membrane

associated with osmosis in Unit 1 it will be necessary to explain that water
molecules are not the only ones able to pass through (N.B. Visking tubing is
available with different-sized pores.)
10(a)

Define homeostasis as the

maintenance of a constant internal
environment

Internal environment may be explained as conditions within the body.

Homeostasis may be split into homeo (meaning the same) and stasis
(meaning staying or standing).
Learners may watch the suggested animated video following which a class

V1 3Y08

Cambridge O Level Biology (5090)

Homeostasis animated video:

www.bbc.co.uk/homeosts
Homeostasis introduction:
www.s-cool.co.uk/what-ishomeostasis

37

Learning objectives

Suggested teaching activities

brainstorm can be used to list the body functions controlled by homeostasis and
the organs involved.

Learning resources

Textbooks:
Burton, I J Topic 13 Homeostasis
Jones, M Unit 11 Homeostasis
Jones, G & Jones, M 10
Homeostasis and Excretion

10(b)

Explain the concept of control by

negative feedback

The operation of a thermostat illustrates the concept well, but it should be

explained that temperature is not the only variable that can be controlled. An
introduction relating to temperature control leads comfortably on to learning
objective 10(d).

Negative feedback cycle:

www.bbc.co.uk/negativefdback

Use the negative feedback cycle diagram to explain the steps involved in
controlling a constant room temperature and then diversify to explain the control
of homeostatic functions in the body listed when studying 10(a) above.
10(c)

Identify, on a diagram of the skin,

hairs, sweat glands, temperature
receptors, blood vessels and fatty
tissue

Provide learners with a labelled diagram of the skin to show the features
required. The suggested online resource may be printed for this purpose and
learners asked to add temperature receptors to the diagram.

Skin (no temp. receptor shown):

www.ewart.org.uk/biology/pics/skin
.gif

10(d)

Describe the maintenance of a

constant body temperature in
humans in terms of insulation and the
role of temperature receptors in the
skin, sweating, shivering, blood
vessels near the skin surface and the
coordinating role of the brain

The functions of the labelled structures are important here. Stress that capillaries
do not move nearer or further away from the skin surface and that they do not
constrict or dilate (as they are not muscular).

Temperature regulation by skin:

www.abpischools.org.uk/page/mod
ules/skin/skin3.cfm

Learners may use the online interactive activity, following which two bullet-point
lists can be made to outline the ways in which the body responds to cause an
increase or decrease in its internal temperature.

Sweating data analysis task:

www.practicalbiology.org/

A more challenging activity is for learners to complete the sweating data

analysis task from the online resources.

5090 past paper questions:

Nov 2011 Paper 21 Q3
Jun 2010 Paper 22 Q4

Describe the role of the brain in monitoring the temperature of blood flowing
through it and the control, via nerves, of the action effectors in the skin to bring
about the changes previously listed.

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Learning objectives

Suggested teaching activities

Learning resources

11(a)

Provide a simple diagram showing the three main parts and explain that all parts
of the body are served by the nervous system.

Nervous system basic diagram:

http://medicalimages.allrefer.com/

An activity to emphasise the importance of the nervous system is for learners to

investigate the speed of their reaction time using the online resources.

Testing reaction time:

www.bbc.co.uk/

A more challenging activity is for learners to deduce the pathway taken by

nervous impulses from the time a stimulus appears to their response. Ask
learners to discuss this after their investigation and to construct a flow diagram.

Human Benchmark test:

www.humanbenchmark.com/

State that the nervous system

brain, spinal cord and nerves, serves
to coordinate and regulate bodily
functions

Textbooks:
Burton, I J Topic 14
Coordination and Response
Jones, G & Jones, M 9
Coordination and Response
Jones, M Unit 12 Coordination
11(b)

Identify, on diagrams of the central

nervous system, the cerebrum,
cerebellum, pituitary gland and
hypothalamus, medulla, spinal cord
and nerves

Provide a labelled diagram of the brain showing the required features - avoid any
further labels not required by the syllabus.

Labelled diagram of brain:

www.epilepsy.org.au/

11(c)

Describe the principal functions of

the above structures in terms of
coordinating and regulating bodily
functions

Learners may use the suggested online resource to add annotations to the
diagram from 11(b) (or to produce a separate table) outlining the major functions
of each named structure.

Brain structure and function:

http://kidshealth.org/

A more challenging activity is for learners to consider the problems that would
be associated with damage to different areas of the brain.

11(d)

Describe the gross structure of the

eye as seen in front view and in
horizontal section

V1 3Y08

5090 past paper question:

Jun 2010 Paper 21 Q7

The front view of the eye may be studied by learners using hand-mirrors and a
list of the structures observed collated. Learners may draw and label the front
view of one of their eyes using a mirror.

Eye anatomy:
www.bbc.co.uk/keeping_in_touch

A demonstration dissection of an eye is a possible extension activity; however

learners often find it difficult to relate eye structure as seen in this way to

Eye and vision, for learning

objectives11(d) to (f):

Cambridge O Level Biology (5090)

39

Learning objectives

Suggested teaching activities

Learning resources

structure as represented diagrammatically.

www.s-cool.co.uk/eye

Invite learners to demonstrate their blind spots by drawing two small circles
about 9 cm apart and moving them towards and away from one eye with the
other closed. The second spot disappears at a distance of about 30 cm.

Eye labelling activities:

www.kscience.co.uk/
www.kscience.co.uk/

Learners may use the suggested online resources to label a diagram of the eye
in horizontal section following which their understanding may be assessed by
providing a large diagram of the eye and laminated cards on which important
labels are written. Learners then place cards on the diagram to label the
components.
11(e)

State the principal functions of

component parts of the eye in
producing a focused image of near
and distant objects on the retina

Explain that refraction of light occurs at both the cornea and the lens (which finetunes the focus depending on the distance away of the object). Explain the
action of the ciliary muscles in reducing tension on the suspensory ligaments as
they contract (note that the ligaments themselves do not contract). Details of rod
and cone cells are not required.

BIOSCOPE CD (2004)
Rat eye

See suggested resources listed

above.

Learners may draw simple ray diagrams of light from both near and distant
objects being focused on the fovea and showing the different shapes of the lens
in each case.
Accommodation may be demonstrated by reading and then looking outside to a
distant object.
11(f)

Describe the pupil reflex in response

to bright and dim light

Working in pairs, learners may observe on one another the effect of turning on a
bench lamp or torch (with a bulb of low rating) held about a metre from the eye.
Learners may draw labelled diagrams of the pupil and iris in each instance and
add annotations to explain their observations.

Iris muscle action in pupil reflex:

www.apsu.edu/
Also see suggested resources
listed above.

Stress the distinction between ciliary and iris muscles. The antagonistic action of
the iris muscles (circular and longitudinal) should be mentioned together with the
reasons for this reflex.
11(g)

Outline the functions of sensory

neurones, relay neurones and motor
neurones

Learners may draw diagrams of the three types of neurone and specify the
function of each possibly following study of 11(h) below.

5090 past paper question:

Jun 2011 Paper 21 Q9

Stress that neurones carry electrical impulses (not messages or signals).

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Cambridge O Level Biology (5090)

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Learning objectives

Suggested teaching activities

11(h)

All learners will be familiar with the rapid withdrawal of their hand when it
accidentally comes in contact with a hot object. This reflex may be used to
introduce the steps and structures involved in a reflex arc. Cross-reference this
example of a spinal reflex with the pupil reflex studied in 11(f) as an example of
a cranial reflex centred on the brain. A labelled diagram may also include
structural details of the arm bones, joints and antagonistic muscle arrangement
required in 12 (a), (b) and (c) below.

Discuss the function of the brain and

spinal cord in producing a
coordinated response as a result of a
specific stimulus (reflex action)

Learners may demonstrate the knee jerk response by striking below their
kneecap with their hand whilst their legs are loosely crossed. Learners may then
write an account, in the form of numbered steps, to explain each step involved in
the reflex arc.

Learning resources

Reflex arc diagram (knee jerk):

http://img.tfd.com/
5090 past paper question:
Nov 2010 Paper 21 Q7

Learners may be invited to identify the stimuli, receptors and effectors in two
other reflex actions including one where the effector is a gland (e.g. salivation
upon smelling food cooking).
11(i)

Define hormone as a chemical

substance, produced by a gland,
carried by the blood, which alters the
activity of one or more specific target
organs and is then destroyed by the
liver

Unit 3 considered substances passing between tissue fluid and blood capillaries.
Here we identify a useful substance passing from cells into the circulatory
system, performing a particular function, then being destroyed. Cross reference
9(a) in this unit as hormones are removed from the body as waste products of
metabolism.

11(j)

State the role of the hormone

adrenaline in boosting the blood
glucose concentration and give
examples of situations in which this
may occur

Ask learners to brainstorm specific fight or flight situations. Invite learners to

offer suggestions for the value of increased blood glucose in these situations.

Describe the signs (increased blood

glucose concentration and glucose in
urine) and treatment (administration
of insulin) of diabetes mellitus

It may be possible to invite a diabetic into the classroom to offer further

information.

Diabetes information websites:

www.diabetes-explained.co.uk/

Learners may use the suggested online resource to research the signs and
treatment of diabetes and to summarise their findings in the form of a brief talk or
presentation.

www.abpischools.org.uk/page/mod
ules/diabetes/index.cfm

11(k)

5090 past paper question:

Nov 2010 Paper 22 Q6

A more challenging activity is to ask learners to list and explain other areas of
their biological knowledge that this learning objective relates to (which include
links with 5(s) in Unit 3 and 8(d) in Unit 4).

Blood sugar control animation:

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Cambridge O Level Biology (5090)

41

Learning objectives

Suggested teaching activities

Learning resources
www.abpischools.org.uk/

12(a)

Identify and describe, from diagrams,

photographs and real specimens, the
main bones of the forelimb (humerus,
radius, ulna and scapula) of a
mammal

Examine the bones (or photographs or drawings of the bones) of a small

mammal. Learners should learn to identify each bone, how they fit together and
the type of joint formed in each case.
Learners may prepare labelled diagrams of their observations.
Where actual specimens and photographs are difficult to obtain, X-ray
photographs may be used to illustrate both the bones and the joints.
An extension activity is for learners to use paper drinking straws to investigate a
model of how bone strength changes with length and bone pairing. Clamp
either one or two paper drinking straws of varying length between two retort
stands. Hang an increasing mass on the straws and record how much mass it
takes for the straws to buckle. Learners should deduce that shorter straws
arranged in pairs provide the strongest arrangement. Ask learners to relate their
findings to the arrangement of bones in the forelimb.

Skeleton:
www.bbc.co.uk/skeleton1
Elbow joint anatomy:
http://images.conquestchronicles.c
om
X-ray photographs of bones and
joints:
www.accessexcellence.org
Textbooks:
Jones, G & Jones, M 11 Support
and Movement
Burton, I J Topic 11 Support,
Movement and Locomotion
Jones, M Unit 13 Support,
Movement and Locomotion
5090 past paper question:
Jun 2010 Paper 61 Q3

12(b)

12(c)

Describe the type of movement

permitted by the ball and socket joint
and the hinge joint of the forelimb

Describe the action of the

antagonistic muscles at the hinge
joint

Learners may locate the prescribed joints on a diagram of the human skeleton
and annotate the diagram to show the type of joint and the type of movement
permitted in each case.

Human skeleton (labelled):

www.learning-connections.co.uk/

Ask learners to identify other examples of ball and socket and of hinge joints in
the body and to add labels to their diagrams to show their location.

Hinge joint anatomy and

movement:
http://kidshealth.org/

These muscles show similarities to those already described in the iris in 11(f).
Muscles work only when they contract - they can pull but never push. Note that
inelastic tendons transmit force to the bones.

Hinge joint animation:

www.purchon.com/biology/flash/el
bow.swf

Use the suggested online resource to review the action of muscles at the hinge

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Cambridge O Level Biology (5090)

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Learning objectives

Suggested teaching activities

Learning resources

joint. Learners may be provided with two copies of a similar diagram and
annotate each to indicate the role of muscles and tendons when the arm is
raised and lowered.

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Cambridge O Level Biology (5090)

43

Scheme of work Cambridge O Level Biology (5090)

Unit 6: Drugs, microorganisms and biotechnology
Recommended prior knowledge
It would be helpful, but not essential, to have a basic understanding of the respiratory system and of the structure of the circulatory system as well as of respiration and
enzymes.
Context
Although the use and abuse of drugs does not sit entirely comfortably with the other topics in the unit, references to bacteria run from antibiotics, through to
microorganisms and biotechnology. The section on drugs picks up on knowledge gained in 5(s) in Unit 3 and 8(j) to 8(l) in Unit 4. Biotechnology re-visits anaerobic
respiration covered in 8(e) and 8(f) in Unit 4.
Outline
Drugs are considered both from the helpful and from the harmful angle. Included in the abuse of drugs is an appraisal of the harmful effects of alcohol and of smoking.
Benefits of microorganisms and their use in various forms of biotechnology are then considered.
Learning objectives

Suggested teaching activities

Learning resources
5090 past question papers are available
at: http://teachers.cie.org.uk

Candidates should be able to:

13(a)

Define a drug as any externally

administered substance that
modifies or affects chemical
reactions in the body

Stress that drugs have side effects, must be taken only in the correct
dosage, only by the person for whom they are prescribed and only when
required.

Textbooks:
Jones, G & Jones, M 13 Health,
Disease and Medicine
Burton, I J Topic 15 The Use and
Abuse of Drugs
Jones, M Unit 14 The Use and Abuse
of Drugs

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Learning objectives

Suggested teaching activities

Learning resources

13(b)

Explain that certain antibiotics are more effective against certain types of
bacteria. Also explain that the more resistant bacteria are the last to be
killed and if the course is not completed, the resistant bacteria survive,
spread and are then much less effectively treated by the same antibiotic.

Antibiotic resistance video clip:

http://hcd2.bupa.co.uk/antibiotics

Describe the medicinal use of

antibiotics for the treatment of
bacterial infection

Learners may watch the suggested online video clip and write a
commentary to help them to understand issues surrounding the
development of antibiotic resistant bacteria.
13(c)

Describe the effects of the abuse of

heroin: a powerful depressant,
problems of addiction, severe
withdrawal symptoms and
associated problems such as crime
and infection e.g. AIDS

Learners should be aware that heroin has a valuable use as an effective

reliever of severe pain. A side effect is to slow down brain functions and
give a feeling of intense well-being, but when addicted, progressively
greater amounts are taken to achieve the same level of euphoria.

Antibiotic resistance information:

www.sumanasinc.com/antibiotic
www.bbc.co.uk/

Heroin facts:
http://faculty.washington.edu/chudler/her
o.html
www.talktofrank.com/drugs.aspx?id=186

Withdrawal from drugs like heroin is extremely uncomfortable, but not

dangerous unless they are mixed with other drugs. Heroin withdrawal on its
own does not produce seizures, heart attacks, strokes, or delirium.

www.bbc.co.uk/health/emotional_health/
addictions/heroin.shtml

Crime is used to fund the habit. If heroin is injected with used needles,
diseases such as AIDS may be spread.

5090 past paper question:

Jun 2011 Paper 22 Q8

Learners may research the biological and social effects of heroin using the
suggested online resources and produce a spider diagram, written
summary or class presentation to summarise the findings of their research.
13(d)

Describe the effects of excessive

consumption of alcohol: reduced
self-control, depressant, effect on
reaction times, damage to liver and
social implications

Note that excessive alcohol consumption is being considered. Social

implications include being a danger to others (e.g. slowed reaction times
when driving) as well as crime committed both when under the influence
and to fund the habit. Liver damage results from excessive long-term
alcohol use cross reference with 5(s) in Unit 3.
Learners may produce a two column table listing the biological and social
effects of excessive alcohol consumption.

13(e)

Describe the effects of tobacco

smoke and its major toxic
components (nicotine, tar and
carbon monoxide) on health: strong

V1 3Y08

Apart from a description of the listed effects, learners should be referred to

their knowledge of lung structure from Unit 4, 8(j), 8(k) and 8(l) for an
explanation of tar coating the walls of the alveoli, for the destruction of cilia
and the consequent build-up of mucus, and for the effect of emphysema.

Cambridge O Level Biology (5090)

Alcohol addiction:
www.bbc.co.uk/alcohol
Alcohol addiction including links to other
useful sites:
www.nhs.uk/live-well/addiction/alcoholaddiction

Tar, nicotine and CO:

www.tree.com/health/smoking-tar.aspx
http://info.cancerresearchuk.org/

45

Learning objectives
association with bronchitis,
emphysema, lung cancer and heart
disease, and the association
between smoking during pregnancy
and reduced birth weight of the
baby

Suggested teaching activities

Learning resources

A variety of research (book and internet) and presentation styles (e.g.

written summaries, class presentations and annotated diagrams) may be
used to appropriately challenge and assess learners understanding of this
theoretical component of the course.

Smoking and pregnancy:

www.bupa.co.uk/pregnancy
Smoking machine demo:
www.practicalbiology.org/

Using a filter pump to draw smoke from a lighted cigarette through a cottonwool filter provides a graphic and effective demonstration of the tar deposit
from one cigarette. Addition of universal indicator shows production of an
acidic gas.
13(f)

Recognise the fact that many

people regard smoking as no
longer socially acceptable

Refer to research on the link between lung cancer and passive smoking,
as well as to the effect on the eyes and clothes of those in the presence of a
smoker.
Teachers may wish to use data from the smoking statistics online resource
to provide more challenging data-handling exercises for learners to
consider.

Passive smoking article:

www.guardian.co.uk/passive-smoking
Smoking statistics:
http://info.cancerresearchuk.org/

Extend learners research skills and provide a global perspective on the

topic by asking learners to research and discuss recent changes in the law
in some countries to restrict the sale of tobacco and/or smoking in public
places. Use the online resources to discuss whether the scope of these
laws should be extended further.
14(a)

List the main characteristics of the

following groups: viruses, bacteria
and fungi

Present learners with labelled diagrams of the external features of each

type of organism. Learners may use the suggested online resource to
produce a supporting table comparing these organisms.

Information and diagrams:

www.peteducation.com/
Textbooks:
Burton, I J Topic 16 The Diversity of
Organisms
Jones, M Unit 15 Micro-organisms and
Biotechnology
Jones, G & Jones, M 14 Making Use of
Microorganisms

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Learning objectives

Suggested teaching activities

Learning resources

14(b)

Explain that the ions, originally absorbed by plants, (cross reference 4(j) in
Unit 2), are released again when bacteria decompose dead plants and
animals in a reverse of the process which attached them to organic
molecules within the plant. Microorganisms release enough energy (as
heat) as they respire during this process that compost/manure heaps
steam, smoke and may even catch fire.

Compost heap stimulus photo:

http://hotdogjam.files.wordpress.com/

Outline the role of microorganisms

in decomposition

Produce a table or spider diagram listing how a range of factors affect the
rate of decomposition.

Time-lapse decay video:

www.bbc.co.uk/
Factors affecting decomposition:
www.bbc.co.uk/decay

A basic activity is to use the stimulus photo showing a steaming compost

heap and/or a video of fruit decaying asking learners to discuss and/or
write a description of the processes occurring.
A more challenging activity is for learners to extend their discussion and
written work to include details of the process occurring to bring about the
changes observed.
14(c)

Explain the role of yeast in the

production of bread and alcohol

V1 3Y08

In 8(e) and 8(f) in Unit 4 learners learnt that a form of anaerobic respiration
(fermentation) turns sugar into alcohol and CO2. Explain that the CO2 is
used in bread making to make the dough rise and the CO2 provides sparkle
to alcoholic drinks in which fruit or other plant sugars are used as the
substrate. Yeast provides a collection of enzymes during anaerobic
respiration to catalyse this process.

Bread making:
www.guardian.co.uk/breadmaking

Learners may use the suggested online resources to research and present
information explaining the science behind the production of these foods.

Demo CO2 production by yeast:

http://image.tutorvista.com/demonstration

A more challenging activity is for learners to use yeast in a glucose

solution to:
i) demonstrate the anaerobic evolution of CO2. The rate may be measured
at different temperatures using a water bath and counting the number of
bubbles released from a narrow delivery tube in unit time.
ii) make dough with flour placed in a measuring cylinder. The rate of CO2
release can be measured as the dough rises up the cylinder. Different
temperatures could be investigated. Measurements could be recorded and
graphs of the rate of respiration (distance risen in unit time) against
temperature could be drawn.

Time-lapse dough rising video:

www.youtube.com/

Cambridge O Level Biology (5090)

47

Learning objectives

Suggested teaching activities

Learning resources

Learners may use data collected from their practical work and use these to
construct tables, draw graphs and write conclusions relating their results to
the supporting theory. Link with work on enzymes from Unit 1.
14(d)

Outline the role of bacteria in

yoghurt and cheese production

The production of lactic acid is now relevant as this is the agent that sours
the milk. Learners may read and discuss the suggested online resource and
produce a written summary of:
i. how bacteria are used to produce yoghurt from milk
ii. how production of yoghurt allows milk to be preserved
Learners may watch the video of cheese production and produce a flow
chart to summarise and explain each of the steps in the production process.

14(e)

Describe the use of fermenters for

large-scale production of antibiotics
and single cell protein

Provide learners with a copy of a labelled diagram of an industrial fermenter

to which they may add annotations to explain the significance of each
feature labelled.
The general principles of controlling amount of substrate and temperature,
sterilisation of utensils, production of large yields in a small space and
purification of product should be covered.

Lactic acid producing bacteria:

www.eufic.org/lactic-acid-bacteria/
Cheese production video:
www.foodafactoflife.org.uk/
5090 past paper question:
Jun 2010 Paper 62 Q3

Fermenter diagram:
www.biotopics.co.uk/microbes/penici.htm
l
5090 past paper question:
Nov 2011 Paper 21 Q6

Even though the substrates are often waste products from other industries
(e.g. molasses from sugar refining), expense can often be a disadvantage.
14(f)

Describe the role of the fungus

Penicillium in the production of
penicillin

Understand the nature of penicillin as a secondary metabolite and the

conditions required for its production.

Discovery of penicillin video:

http://videos.howstuffworks.com/

A more challenging activity is for learners to watch the online video

summarising the discovery of penicillin and to write an outline describing
how the methods used in penicillins early production are in contrast to the
large commercial production of the drug today.

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Cambridge O Level Biology (5090)

48

Scheme of work Cambridge O Level Biology (5090)

Unit 7: Organisms and the environment
Recommended prior knowledge
Learners should have knowledge of the different forms of energy, of plant nutrition, respiration and transpiration. Knowledge of the great diversity of life and habitats
would be helpful.
Context
This unit, whilst considering some of the fundamental topics of biology also takes a broader view of the subject and investigates some of the ethical issues raised by
human interference with the environment.
Outline
Energy flow is traced through biological systems and the carbon and nitrogen cycles are considered in some detail. There is a reference to parasitism in the shape of the
transmission and control of malaria, but control measures employed lead into a consideration of the human effect on the ecosystem in a wider sense deforestation,
pollution and damage to habitats leading to a need for conservation.
Learning objectives

Suggested teaching activities

Learning resources
5090 past question papers are available
at: http://teachers.cie.org.uk

Candidates should be able to:

15(a)

State that the Sun is the principal

source of energy input into biological
systems

Stress that it is light energy from the Sun which is important in

photosynthesis, but enzymes controlling all metabolic reactions rely also
on its heat energy to provide a suitable temperature for their operation.

Organisms and the environment

suitable for a number of learning
objectives in this unit:
www.lgfl.skoool.co.uk/

Textbooks:
Burton, I J Topic 17 The Relationship
between Organisms and the Environment
Jones, M Unit 16 Organisms and
Environment

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49

Learning objectives

Suggested teaching activities

Learning resources

Jones, G & Jones, M 15 Living

organisms and their environment
15(b)

Describe the non-cyclical nature of

energy flow

Once energy is released by organisms it is lost and can be replaced only

by further input, directly or indirectly, from the Sun.

15(c)

Define the following terms and

establish the relationship of each in
food webs: producer, consumer,
herbivore, carnivore, decomposer,
food chain

Learners may be able to suggest food chains in various different habitats.

15(d)

Describe energy losses between

trophic levels and infer the
advantages of short food chains

Food chains and terminology:

www.bbc.co.uk/

Learners may be provided with a food chain of at least three organisms,

starting with a producer and write each of the specified words underneath
the appropriate component of the food chain provided.

Interactive food chain:

www.puzzling.caret.cam.ac.uk/

If learners have the opportunity to visit a habitat, even if only in the school
grounds, they may construct a food chain based on their observations.

5090 past paper question:

Jun 2010 Paper 22 Q7(a)

In Unit 8(d) in unit 4 learners considered the use of energy for different
processes in a body thus there is always less energy available to each
successive level in a food chain or web.

Energy transfer:
www.bbc.co.uk/sfoodchains2

Use the suggested online resource called energy transfer to review the
ways in which energy may be lost between trophic levels. Learners may
make a bullet-point list of these and explain why food chains are
commonly limited in length.
The efficiency of food production in terms of placing humans as primary
consumers and of reducing energy losses through factory farming may be
discussed with reference to named examples (including chickens and
pigs) generated by learners. The video clips may be used to introduce and
to reinforce this learning objective.

Video clips energy transfer in food

chains:
www.bbc.co.uk/
www.bbc.co.uk/lfood-chains
Video clip food chain energy:
www.bbc.co.uk/
Agricultural change in the Paris Basin:
intensive farming:
www.bbc.co.uk/
5090 past paper question:
Jun 2010 Paper 21 Q1

15(e)

Describe and interpret pyramids of

numbers and of biomass

V1 3Y08

It should be explained why pyramids of biomass (which are of typical

pyramid shape) provide a more accurate representation of energy

Cambridge O Level Biology (5090)

Video clip pyramid of numbers:

www.bbc.co.uk/numbers

50

Learning objectives

Suggested teaching activities

relationships between organisms in a food chain or food web than
pyramids of numbers (many of which are not the typical pyramid shape).

Learning resources

Pyramids of biomass:
hwww.bbc.co.uk/foodchains3l

Learners may draw and explain pyramids of number and biomass for food
chains introduced earlier in the unit. They may link the shape of biomass
pyramids to the knowledge gained in 15(d). Extend learners
understanding to include food chains which are atypical (e.g. where there
is a single large producer or where the top consumer is a parasite).
A more challenging activity is for learners to draw pyramids to scale
using graph paper if numbers and/or biomasses are given.
An extension opportunity is for learners to collect leaf litter or to collect
invertebrates from grassland (using sweep nets) or trees (by shaking
branches) and to construct a pyramid of numbers or biomass based on
classification of the organisms found.
15(f)

Describe and state the importance of

the carbon cycle

This objective stresses the fact that life is carbon-based and is an

opportunity to consolidate topics covered in Units 2, 3 and 4.

The carbon cycle info and diag.:

www.bbc.co.uk/foodchains5

Learners may list and then arrange into a sequence all the processes they
have studied which involve carbon compounds. The cyclical nature of
these processes should become apparent.

Carbon cycle animated video:

www.bbc.co.uk/foodchainact

Learners may be given cards showing stages of the carbon cycle and
asked to arrange them into a complete cycle. An extension activity is for
the objective of this task to be presented in the form of a poster or
classroom display.

Practical Biology Carbon Cycle:

www.practicalbiology.org/
5090 past paper question:
Jun 2011 Paper 21 Q7(a)

A more challenging way of covering this learning objective is to ask

learners to describe, as fully as possible; the fate of an atom of carbon
after it has entered a plant in a CO2 molecule during photosynthesis, thus
building up their own carbon cycles. These may then be combined to
provide (perhaps with a few additions/adjustments) the definitive version
for distribution.
The suggested online resources may be used to provide additional stimuli
and assistance during or following the above activities.

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Learning objectives

Suggested teaching activities

Learning resources

Extension activities may include learners considering what is meant by

the term carbon neutral or using the suggested online resource to
investigate the effect of microbes in the decay of cellulose.
15(g)

Describe the nitrogen cycle in making

available nitrogen for plant and
animal protein, including the role of
bacteria in nitrogen fixation,
decomposition and nitrification
(details of denitrification and the
names of individual bacteria are not
required)

Learners may attempt to brainstorm the nitrogen cycle in a similar way to

the carbon cycle. Cross reference with decomposition considered in 14(b)
in Unit 6.
Learners tend to find this cycle difficult to understand and remember. It is
therefore wise to avoid unnecessary detail. The suggested online
resources present the topic at an appropriate level.
Learners may use the talking explanation of the nitrogen cycle to write a
set of bullet-point notes to explain each step underlining the different
types of bacteria involved.
Distinguish carefully between the terms nitrogen fixation and nitrification.
Reference should be made to bacteria in the root nodules of leguminous
plants as well as to those which are free-living. The photograph of root
nodules may be used to aid explanation of the role of leguminous plants.

Simple nitrogen cycle diagrams:

www.s-cool.co.uk/nature
Talking explanation and animation of the
nitrogen cycle:
www.nodvin.net/sanimations
Photograph of root nodules:
http://blog.lib.umn.edu/AlfalfaNodules5.jp
g
Video clip nutrient recycling:
www.bbc.co.uk/learningzone/clips/recycli
ng-nutrients/4172.html

Learners may be given cards or statements describing aspects of the

nitrogen cycle and arrange them into a complete cycle. The video clip may
be used to consolidate this task.
15(h)

Understand the role of the mosquito

as a vector of disease

Indicate how the lifestyle of the mosquito makes it a successful vector of a

wide variety of diseases. Stress that the mosquito is the carrier (vector) of
the pathogen but does not itself cause malaria. Ways in which control of
the mosquito vector is achieved should be considered here.
Learners may use the suggested online resources to research the lifestyle
and control of the mosquito vector and present their findings in the form of
a poster, fact sheet or brief presentation to the class.
It is possible for some learners to research and summarise 15(h) whilst
others do so for 15(i). Learners may subsequently share their findings.

V1 3Y08

Cambridge O Level Biology (5090)

Mosquito vector and control:

www.cdc.gov/malaria/about/biology/mosq
uitoes/index.html
World Health Organisation malaria fact
sheet:
www.who.int/mediacentre/factsheets/fs09
4/en/index.html
Textbook:
Jones, G & Jones, M 13 Health,
disease and medicine

52

Learning objectives

Suggested teaching activities

Learning resources

15(i)

Describe the malaria pathogen as an

example of a parasite and describe
the transmission and control of the
malarial pathogen (details of the life
cycle of the pathogen are not
required)

Control of the pathogen both before and after it has entered the body
should be considered here.

See suggested resources listed above.

Describe the effects of humans on

the ecosystem with emphasis on
examples of international importance
(tropical rain forests, oceans and
important rivers)

Action which affects large areas in one part of the world may have
consequences in another (e.g. global warming, scarcity or contamination
of fish supplies). Loss of habitats leads to extinction of species and to loss
of possible benefits from those species (e.g. drugs). Action taken in one
region near a river can cause flooding and devastation hundreds of miles
away.

Tropical rain forests:

http://environment.nationalgeographic.co
m/environment/habitats/rainforestthreats/

The effects of deforestation and other effects of humans could be

discussed using newspaper/media articles. These may be either provided
by the teacher or a more challenging activity is for learners to provide
these.

www.bbc.co.uk/learningzone/clips/sustai
nable-forestry-using-animalpower/11966.html

15(j)

As above, learners may use the suggested online resources to research

the lifestyle and control of the mosquito vector and present their findings in
the form of a poster, fact sheet or brief presentation to the class.

Learners may be divided into three groups with each group studying in
depth, using the suggested online resources, one example of the effects
of humans on the ecosystem. Learners may present their findings in the
form of a report or presentation to exchange with others.

www.bbc.co.uk/

www.bbc.co.uk/learningzone/clips/natural
-balance-threats-to-therainforest/4712.html
Oceans:
www.protectplanetocean.org/introduction/
introduction.html
Rivers:
www.internationalrivers.org/
www.bbc.co.uk/learningzone/clips/whyhave-fish-stocks-decreased-in-the-northsea-pt-1-2/4687.html
Textbooks:
Jones, M Unit 17 Human Effects on
Ecosystems
Burton, I J Topic 18 The Effects of
Human Activity on the Ecosystem

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Learning objectives

Suggested teaching activities

Learning resources

Jones, G & Jones, M 16 Humans and

the environment
15(k)

Describe the consequences of

deforestation in terms of its effects on
soil stability, climate and local human
populations

The removal of trees removes the binding effect their roots have on the
soil as well as the protection their canopies provide from sun, wind and
rain. The humus their dead leaves provide is also lost. Local populations
may lose homes and livelihoods. Climate changes are usually
experienced at greater distances from the site of deforestation.

Deforestation:
www.bbc.co.uk/dna/h2g2/A3556848

Learners may use the list of points outlined above and the suggested
online resource to produce a spider diagram showing the consequences
of deforestation.
www.the-organic-mind.com/spider-diagrams.html
15(l)

Evaluate the effects of:

water pollution by sewage, by
inorganic waste and by nitrogen
containing fertilisers
air pollution by greenhouse gases
(carbon dioxide and methane),
contributing to global warming
air pollution by acidic gases (sulfur
dioxide and oxides of nitrogen),
contributing to acid rain
pollution due to insecticides

V1 3Y08

Learners should be made aware of the damage being caused to the

planet by the stated forms of pollution and that it is when the materials
mentioned are used or released in excess that problems occur.
Eutrophication should be considered as an effect of water pollution by
sewage and N2 fertilisers, as should the build up along food chains of
insecticides which cannot be metabolised. An opportunity exists here to
consolidate earlier work on the nitrogen cycle.

Water pollution:
www.water-pollution.org.uk/
Combustion products:
www.bbc.co.uk/schools/gcsebitesize/scie
nce/21c/atmosphere/chemicalreactionsre
v2.shtml

Ensure that there is a clear distinction in learners minds between the use
of fertilisers and the use of insecticides.

Greenhouse effect animation:

http://earthguide.ucsd.edu/earthguide/dia
grams/greenhouse/

Learners may produce a set of flow charts to list the steps involved in the
processes of eutrophication, global warming and the production of acid
rain.

Acid rain:
www.supergreenme.com/go-greenenvironment-eco:Acid-Rain

Learners may produce a poster or information leaflet describing the

effects of the stated forms of pollution.

www.nationalstemcentre.org.uk/elibrary/r
esource/1728/acid-rain

The distinction between causes and consequences may be clearly

made by asking learners to list these in two columns of a table for each
form of pollution.

www.bbc.co.uk/learningzone/clips/airpollution-and-its-effects-on-theenvironment/6008.html

Cambridge O Level Biology (5090)

54

Learning objectives

Suggested teaching activities

Learning resources

15(m)

Many of the points relevant here will have been considered in 15(j) and
15(k) above. The concept of sustainable management of fish (via quotas)
and timber supplies should be promoted.

Species conservation:
www.admwebstudios.co.uk/Biodiversity3.
htm#preserve

Learners may research specific examples of species or ecosystems which

are actively being conserved, the methods by which this is being achieved
and the reasons why their conservation is important. Learners may
present their findings in a variety of formats.

Conserving Biodiversity:
www.nationalstemcentre.org.uk/elibrary/r
esource/1738/biodiversity-around-us

Discuss reasons for conservation of

species with reference to
maintenance of biodiversity,
management of fisheries and
management of timber production

Video clips conservation:

www.bbc.co.uk/learningzone/clips/biodiv
ersity-and-the-humanimplications/5505.html
www.bbc.co.uk/learningzone/clips/lochlomond-land-use-conservation/1142.html
5090 past paper question:
Jun 2010 Paper 22 Q7(b)
15(n)

Discuss reasons for recycling

materials, with reference to named
examples

Depletion of the planets resources is of concern. Deforestation for paper

production may be reduced by paper recycling and energy may be saved
by recycling glass. Recycling metal (from cans to cars) saves both energy
and reduces the need to mine the ore.
The suggested online resource may be used by learners to research the
topic further. Learners may produce a poster or information leaflet, for use
in their school or community, to promote the benefits of recycling.

V1 3Y08

Cambridge O Level Biology (5090)

Metal, paper, plastic and glass recycling:

www.thriftyfun.com/tf42552953.tip.html
Video clip recycling waste:
www.bbc.co.uk/learningzone/clips/recycli
ng-and-the-incineration-ofwaste/1577.html

55

Scheme of work Cambridge O Level Biology (5090)

Unit 8: Continuity of life reproduction
Recommended prior knowledge
The major part of this unit stands alone. Helpful, but not essential, would be a knowledge of cell structure, enzymes, nutrition and excretion and bacteria.
Context
The general thread of reproduction runs throughout the unit.
Outline
First, reproduction is considered in general terms, and then sexual reproduction in both plants and animals is addressed. Sexually transmitted diseases are studied
together with their control.
Learning objectives

Suggested teaching activities

Learning resources
5090 past question papers are available
at http://teachers.cie.org.uk

Candidates should be able to:

16(a)

16(b)

V1 3Y08

Define mitosis as cell division giving

rise to genetically identical cells in
which the chromosome number is
maintained and state the role of
mitosis in growth, repair of damaged
tissues, replacement of worn-out
cells and asexual reproduction

The nucleus of a cell contains a number of chromosomes and that the

number is fixed and constant for each species (46 in the human being). A
new body cell must be an exact copy of the cell producing it. (Details of
the stages in mitosis are not required.)

Mitosis:
www.bbc.co.uk/schools/gcsebitesize/scie
nce/add_aqa/celldivision/celldivision2.sht
ml

Use the suggested online resource to guide learners through the basic
steps of the procedure and ask them to consider the genetic significance
of each.

Textbooks:
Jones, G & Jones, M 8 Reproduction

Define asexual reproduction as the

process resulting in the production of
genetically identical offspring from
one parent and describe one named,
commercially important application of
asexual reproduction in plants

For the chosen commercial application (e.g. a potato tuber) learners

should understand the benefits and the disadvantages of this method of
reproduction.
Learners may produce a table comparing the benefits and disadvantages
together with an outline of how the technique is used in a named

Cambridge O Level Biology (5090)

Jones, M Unit 18 Reproduction in

Plants
Burton, I J Topic 20 Reproduction
5090 past paper question:
Jun 2010 Paper 21 Q8

56

Learning objectives

Suggested teaching activities

Learning resources

commercially important application.

Practical Biology Cloning:

www.practicalbiology.org/areas/intermedi
ate/genetics/introducing-genetechnologies/cloning-a-livingorganism,43,EXP.html

An extension practical activity is for learners to use the suggested online

resource in order to make clones by taking cuttings.

16(c)

Define meiosis as a reduction

division in which the chromosome
number is halved from diploid to
haploid

Details of meiotic division are not required other than its role in halving of
the chromosome number. The terms gamete, diploid and haploid should
be explained.

Meiosis:
www.bbc.co.uk/schools/gcsebitesize/scie
nce/add_aqa/celldivision/celldivision4.sht
ml

Use the suggested online resource to guide learners through the basic
steps of the procedure and ask them to consider the genetic significance
of each. Compare the objective and process with that of mitosis from
16(a).
16(d)

State that gametes are the result of

meiosis (reduction division)

Link this learning objective with coverage of 16(c) above.

16(e)

Define sexual reproduction as the

process involving the fusion of
haploid nuclei to form a diploid
zygote and the production of
genetically dissimilar offspring

Learners should appreciate that each parent therefore makes an equal

contribution to the diploid cell from which an offspring will develop.

Identify and draw, using a hand lens

if necessary, the sepals, petals,
stamens and carpels of one, locally
available, named, insect-pollinated,
dicotyledonous flower, and examine
the pollen grains under a light
microscope

If possible a large, brightly-coloured, scented flower with visible nectar

should be chosen. Ensure that learners produce large drawings, with a
sharp HB pencil, draw clean lines and give the magnification of their
drawing (e.g. x3).

16(f)

Learners may draw a flow chart showing gametes, zygote and embryo
onto which they may annotate each stage to show the chromosome
number (n or 2n) and type of cell division (mitosis or meiosis) involved.

Use the suggested online resources to assist learners in their identification

of the listed components.

Learners may make posters or classroom displays showing flower

structure using the suggested online resources and/or their own
observations.

V1 3Y08

Downloadable PowerPoint presentation

covering all aspects of 16(f) to 16(p):
www.clickbiology.com/wpcontent/uploads/2010/01/plantreproduction.ppt

Cambridge O Level Biology (5090)

Components of flowering plant:

www.bbc.co.uk/schools/ks2bitesize/scien
ce/living_things/plant_life_cycles/read1.s

57

Learning objectives

Suggested teaching activities

Learning resources
html
Flower structure:
www.biology-resources.com/plantsflowers.html
Flower structure:
www.saps.org.uk/secondary/teachingresources/547-the-structure-of-flowers

The interactive flower activities provide an opportunity for learner selfassessment once the learning objective has been covered.

Interactive flower activities:

www.bbc.co.uk/schools/scienceclips/age
s/9_10/life_cycles.shtml
www2.bgfl.org/bgfl2/custom/resources_ft
p/client_ftp/ks2/science/plants_pt2/parts.
htm

16(g)

State the functions of the sepals,

petals, anthers and carpels

It will be necessary to explain that carpels are made up of component

parts stigma, style, ovary and ovules. Also ensure that learners are clear
that pollen (grains) are not gametes but that they contain the gametes.

See suggested resources listed above.

Learners may use information from a text book or from the suggested
online resources to annotate their diagrams from 16(f) to show the
functions of the components labelled. Further suggested activities relevant
to this learning objective are listed against 16(f) above.

16(h)

Use a hands lens to identify and

describe the anthers and stigmas of
one, locally available, named, windpollinated flower, and examine the
pollen grains under a light
microscope

V1 3Y08

An extension activity is for learners to research the nature and function of

nectar guides on the petals of some plant species. These are visible only
under UV light as shown in the suggested online resource.

Nectar guides:
www.dailymail.co.uk/sciencetech/article473897/A-bees-eye-view-How-insectsflowers-differently-us.html

Note that a drawing is not required.

Types of pollen:
www.sciencephoto.com/features/1132Pollen.pdf

Learners may list any noticeable differences from the features seen in the
insect-pollinated flower and attempt to account for each of the differences
observed.

Cambridge O Level Biology (5090)

58

Learning objectives

Suggested teaching activities

Learning resources

Learners may use their own observations and the suggested online
resource to note differences in the amount and structure of pollen
produced by insect and wind pollinated flowers and attempt to account for
any differences.
16(i)

Outline the process of pollination and

distinguish between self-pollination
and cross-pollination

Learners may draw and annotate summary diagrams to outline the

transfer of pollen between named flower parts in the two processes.
Learners may describe the differences between the two processes and
produce a list of the advantages and disadvantages of each method.

16(j)

Compare, using fresh specimens, an

insect-pollinated and a windpollinated flower

See learning objectives 16(f) to 16(h) above.

Video clip Insect pollination:

www.bbc.co.uk/learningzone/clips/insectpollination-of-plants/119.html

16(k)

Describe the growth of the pollen

tube and its entry into the ovule
followed by fertilisation (production of
endosperm and details of
development are not required)

Use a diagram to show the path taken by the pollen tube.

Pollen tube diagram:

http://staff.tuhsd.k12.az.us/gfoster/standa
rd/ovule.jpg

Learners may use the suggested online animation to add annotations to a

labelled diagram. Note, the level of detail in the animation is quite
advanced yet provides a good link back to the nature of haploid and
diploid cells.

A more advanced extension activity is for learners to attempt to grow

pollen tubes using the practical technique outlined in the suggested online
resource.

Video clips and animations:

www.bbc.co.uk/learningzone/clips/fertilis
ation-in-plants/120.html
www.emunix.emich.edu/~ghannan/systb
ot/doublefertanimation.html
Pollen tube growth practical:
www.saps.org.uk/secondary/teachingresources/222-student-sheet-4-pollentube-growth

16(l)

Investigate and describe the

structure of a non-endospermic seed
in terms of the embryo (radicle,
plumule and otyledons) and testa,
protected by the pericarp (fruit wall)

Learners may dissect pea or large bean seeds, soaked for 24 hours
before use, and make labelled drawings of the components identified
using online and textbook references as a source of information.

16(m)

State that seed and fruit dispersal by

The class may brainstorm advantages of the ability of plants to colonise

V1 3Y08

Cambridge O Level Biology (5090)

See Powerpoint resource listed in 16(f).

59

Learning objectives

16(n)

Suggested teaching activities

wind and by animals provides a

means of colonising new areas

new areas.

Describe the external features of

one, locally available, named
example of a wind-dispersed fruit or
seed and of one named example of
an animal-dispersed fruit or seed

Stress that fruit and seed dispersal by wind or animals can happen only
after pollination (by wind or insects) and the two very different processes
must not be confused.
Although there are adaptations for different methods of animal dispersal,
only one need be considered in detail. Learners may each (or in small
groups) consider a different method and then present their findings to
other learners in a variety of formats. The activity may then be extended
by asking learners to compare the likely effectiveness of the different
animal seed-dispersal mechanisms.

Learning resources

Websites for seed dispersal

mechanisms:
www.britannica.com/EBchecked/media/1
45426/Seeds-and-their-dispersalmechanisms
www2.bgfl.org/bgfl2/custom/resources_ft
p/client_ftp/ks2/science/plants_pt2/disper
sal.htm
www.mbgnet.net/bioplants/seed.html

Learners may research and produce large, annotated diagrams of each

seed to explain how their features enable seed-dispersal by the relevant
method.

16(o)

Investigate and state the

environmental conditions that affect
germination of seeds: suitable
temperature, water and oxygen

Wind dispersal mechanisms:

http://waynesword.palomar.edu/plfeb99.h
tm

Note that warmth is scientifically vague and that seeds surrounded by

moisture rather than water do not germinate.
Containers of seeds may be set up, one lacking only a suitable
temperature (placed in fridge at approx 4oC), one lacking only water and
one lacking only oxygen (sealed and containing alkaline pyrogallol). A
control, with seeds exposed to all three conditions, should also be
included. A hypothesis may be made for each set of seeds, following
which the germination progress of each set should be noted following a
period of time. The results may be compared and explanations for any
differences noticed may be suggested.

See PowerPoint resource listed in 16(f)

for diagrams showing this experimental
design.

A more challenging activity is to ask learners to aid the planning of this

investigation by considering experimental design including variables to
alter, measure and control.
For reasons of safety and expense, the pyrogallol container might take the
form of a teacher demonstration.

V1 3Y08

Cambridge O Level Biology (5090)

60

Learning objectives

Suggested teaching activities

Learning resources

16(p)

Cross reference with learning objective 5(o) of Unit 3. The need to convert
insoluble storage compounds into soluble ones which can be transported
should be stressed.

See PowerPoint resource listed in 16(f)

for animated content.

Describe the uses of enzymes in the

germination of seeds

Learners may use the appropriate section of the suggested online

PowerPoint resource to gain an understanding of the process, following
which they may produce a written or flow-chart summary of the key
events.
16(q)

Identify on diagrams of the male

reproductive system and give the
functions of the testes, scrotum,
sperm ducts, prostate gland, urethra
and penis

Learners may use the suggested online or textbook resources to label a

diagram of the components required. Learners should be able to interpret
both front and side views.

Video clip germination:

www.bbc.co.uk/learningzone/clips/anintroduction-to-seed-germination-andgrowth/63.html

Male reproductive anatomy:

www.passmyexams.co.uk/GCSE/biology/
images/reproductive_system_male.jpg
Textbooks:
Burton, I J Topic 21 Sexual
Reproduction in Human Beings
Jones, M Unit 19 Reproduction in
Humans

16(r)

Identify on diagrams of the female

reproductive system and give the
functions of the ovaries, oviducts,
uterus, cervix and vagina

Learners may use the suggested online or textbook resources to label a

diagram of the components required. Learners should be able to interpret
both front and side views.

Female reproductive anatomy:

www.passmyexams.co.uk/GCSE/biology/
images/reproductive_system_female.jpg

16(s)

Compare male and female gametes

in terms of size, numbers and
mobility

Comparisons should be supported by reasons for the differences and may

be presented in the form of a table.

Fertilisation stimulus photo:

http://image3.examiner.com/images/blog/
wysiwyg/image/Sperm-egg(1).jpg

Use the stimulus photo to introduce difference in size.

16(t)

Describe the menstrual cycle, with

reference to the alternation of
menstruation and ovulation, the
natural variation in its length and the
fertile and infertile phases of the
cycle

V1 3Y08

Annotated diagrams showing the cycle divided into days and showing the
build-up and breakdown of the uterus lining are helpful.
Learners may use the suggested online resource to produce a timeline of
the events comprising the menstrual cycle.

Events of the menstrual cycle:

http://lgfl.skoool.co.uk/content/keystage3/
biology/pc/learningsteps/MENLC/launch.
html
Hormones in the menstrual cycle:
www.bbc.co.uk/schools/gcsebitesize/scie
nce/aqa/human/hormonesrev3.shtml

Cambridge O Level Biology (5090)

61

Learning objectives

Suggested teaching activities

Learning resources

16(u)

Explain the role of hormones in

controlling the menstrual cycle
(including follicle-stimulating
hormone (FSH), luteinizing hormone
(LH), progesterone and oestrogen)

Learners may use the suggested online resource to understand the role of
these hormones. This may be followed by learners preparing a bullet-point
list for each hormone to summarise their respective roles.

Menstrual cycle hormones:

www.abpischools.org.uk/res/coResourceI
mport/modules/hormones/enflash/menstrualCycle.cfm

Describe fertilisation and early

development of the zygote simply in
terms of the formation of a ball of
cells that becomes implanted in the
wall of the uterus

The location of fertilisation should be clearly described. Division of the

zygote by mitosis prior to implantation should be referred to.

State the function of the amniotic sac

and the amniotic fluid

Ways in which the embryo is protected by the fluid (contained by the sac)
should be listed by learners.

16(v)

16(w)

A more challenging extension activity is for learners to then add

information regarding the level of each hormone to the timeline produced
in 16(t) above.
Fusion of gametes:
www.bbc.co.uk/schools/gcsebitesize/scie
nce/aqa/evolution/reproductionrev2.shtml

Learners may watch the video accompanying the suggested online

resource, following which they may produce a written commentary of the
key events.
Amniotic fluid and sac:
www.medhelp.org/medicalinformation/show/6168/The-role-ofamniotic-fluid
www.babiesonline.com/articles/health/am
nioticfluid.asp

16(x)

Describe the function of the placenta

and umbilical cord in relation to
exchange of dissolved nutrients,
gases and excretory products (no
structural details are required)

Stress that maternal and fetal bloods do not mix.

The content of this learning objective may be linked to those covering
diffusion and excretion in previous Units.

5090 past paper questions:

Nov 2011 Paper 21 Q7a
Nov 2010 Paper 22 Q8

Learners may produce a list of the substances which cross the placenta
and indicate the direction of movement of each.
16(y)

Describe the special dietary needs of

pregnant women

Learners may use the suggested online or textbook resources to produce

a two-column table listing the dietary needs and the importance of each.7

Pregnancy dietary advice:

www.eatwell.gov.uk/agesandstages/preg
nancy/whenyrpregnant/

Cross reference may be made with unit 3 (animal nutrition).

16(z)

Describe the advantages of breast

V1 3Y08

The advantages may be presented by learners in the form of a bullet point

Cambridge O Level Biology (5090)

Breast and bottle feeding:

62

Learning objectives
milk compared with bottle milk

Suggested teaching activities

Learning resources

list.

http://kidshealth.org/parent/growth/feedin
g/breast_bottle_feeding.html#
5090 past paper question:
Nov 2011 Paper 21 Q7b

16(aa)

Describe the following methods of

birth control -natural, chemical
(spermicides), mechanical, hormonal
and surgical

Family planning clinics are often helpful in supplying information and

exhibits. Learners may be shown examples of different types of
contraceptive if available.

Birth-control methods:
www.clearblue.com/uk/contraception.php
www.avert.org/teens-condoms.htm

A simple description of the biological basis of the different types of birth

control is required. Learners should also understand the relative
effectiveness of each. Discussion may be extended to include the ways in
which religious or cultural beliefs can affect their use. The advantages of
condoms in reducing the risk of transmitting sexually transmitted
infections.
Learners may use the suggested online resource to research information
on specific examples and present their findings in a variety of formats.
Note that abortion is not considered to be a method of birth control.
16(bb)

Explain that syphilis is caused by a

bacterium that is transmitted during
sexual intercourse

The potentially severe nature of syphilis should be mentioned, together

with concern that AIDS has diverted attention away from other STDs. The
need for early treatment should be stressed.

16(cc)

Describe the symptoms, signs,

effects and treatment of syphilis

Learners may research the specified aspects of the disease and present
their findings in the form of a spider-diagram.

Syphilis:
http://herpescoldsores.com/std/syphilis.htm

16(dd)

Discuss the spread of human

immunodeficiency virus (HIV) and
methods by which it may be
controlled

Ensure that learners are aware that no cure is yet available yet with care
the spread of HIV may be restricted.

HIV/AIDS:
www.abpischools.org.uk/page/modules/di
seases/diseases3.cfm

Learners construct a two column table showing the ways in which HIV is
spread and, for each, the methods by which its spread may be controlled.
A more challenging activity is for learners to extend their understanding
to include the socioeconomic, religious and cultural factors that influence

V1 3Y08

Cambridge O Level Biology (5090)

How HIV is spread:

www.sfaf.org/aids101/transmission.html#
transmitted

63

Learning objectives

Suggested teaching activities

Learning resources

the effectiveness of the control methods in different parts of the world.

Control of HIV:
www.avert.org/aids-hiv-prevention.htm

An extension activity is for learners to research some of the most up-todate medical advances in the drug-related control of HIV.

V1 3Y08

Cambridge O Level Biology (5090)

64

Scheme of work Cambridge O Level Biology (5090)

Unit 9: Continuity of life inheritance and evolution
Recommended prior knowledge
The major part of this unit stands alone. Helpful, but not essential, would be a knowledge of cell structure, enzymes, nutrition and excretion and bacteria.
Context
The general thread of reproduction continues to run through this unit from Unit 8. Genetic inheritance leading on to variation and finally to evolution is considered.
Outline
The importance of DNA is considered along with simple inheritance. A study of variation leads to an explanation of evolution. The unit ends with DNA function and
genetic engineering.
Learning objectives

Suggested teaching activities

Learning resources
5090 past question papers are available
at http://teachers.cie.org.uk

Candidates should be able to:

17(a)

Describe the difference between

continuous and discontinuous
variation and give examples of each

Body weight and height are standard examples of continuous variation, as

are blood groups and sex of discontinuous variation.

Types of variation:
www.bbc.co.uk/variation_classification/l

Learners may collect data concerning these characteristics amongst their

peers and draw graphs to compare the distributions. Graphs should be
drawn of the distributions shown by the two types of variation. Non-human
variation may be investigated by measuring the diameter o
f a selection of leaves taken from the same tree.

Causes of variation:
www.bbc.co.uk/variation_classification

Graphs may be annotated to indicate the influence of genes and/or

environment on each type of variation.

Investigating variation in humans:

www.practicalbiology.org/

Textbooks:
Burton, I J Topic 22 Inheritance
Jones, G & Jones, M 12 Inheritance and
evolution

V1 3Y08

Cambridge O Level Biology (5090)

65

Learning objectives

Suggested teaching activities

Learning resources
Jones, M Unit 20 Inheritance

17(b)

State that a chromosome includes a

long molecule of DNA

Detail of DNA structure is not required beyond a description as two long

strands cross-linked by a succession of paired molecules called bases.
Learners may use the suggested online activity on genome structure,
following which they may write a written summary of the levels of
organisation found in the genome.

Chromosome structure:
www.johnkyrk.com/chromosomestructure.
html
Genome organisation:
http://genome.wellcome.ac.uk/interactive/
zoom/index.html
Introduction to genetics:
www.learn.genetics.utah.edu/content/begi
n/tour/
Genetic terminology:
www.siskiyous.edu/class/bio1/genetics/ge
netic_terms_v2.html
Genes and inheritance:
www.abpischools.org.uk/page/modules/ge
nome/index.cfm

17(c)

State that DNA is divided up into

sections called genes

Explain that, as a consequence, each gene comprises its own particular

sequence of linked bases.
Learners may include this concept in their response to the suggested
activity in 17(b) and may use the suggested online resource covering
genetic terminology as consolidation.

17(d)

Explain that genes may be copied

and passed on to the next generation

Explain that when a cell divides its nucleus first makes an exact copy of
each strand of DNA (and therefore also of each gene). The original
passes into the nucleus of one cell and its copy passes into the other. In
this way, the same genes are passed from generation to generation.

See suggested online resources for

learning objectives 16(a) and (c) of Unit 8.

Cross reference with resources and activities used in 16(a) and 16(c) in
Unit 8.
17(e)

Define a gene as a unit of inheritance

V1 3Y08

Each gene is a length of DNA that may be passed from parent to

Cambridge O Level Biology (5090)

Alleles and complete dominance:

66

Learning objectives
and distinguish clearly between the
terms gene and allele

Suggested teaching activities

Learning resources

offspring. Alleles are alternate forms of the same gene. Many genes have
many different alleles.

www.bbc.co.uk/schools/gcsebitesize/scie
nce/21c/genetics/genesinheritencerev5.sh
tml

A possible link to 17(q) may be made at this time.

Video clips inheritance:
www.bbc.co.uk/learningzone/clips/inherita
nce-of-eye-colour/10651.html
www.bbc.co.uk/learningzone/clips/domina
nt-and-recessivecharacteristics/4197.html
17(f)

Describe complete dominance using

the terms dominant, recessive,
phenotype and genotype

These terms follow naturally from a consideration of genes and alleles

above and are better explained alongside their use in 17(i) when genetic
crosses are presented.

17(g)

Describe mutation as a change in the

structure of a gene (sickle cell
anaemia) or in the chromosome
number (47 in Downs syndrome
instead of 46)

Genes are subject to mutations leading to a change in phenotype. Whilst

most changes are very small and barely noticeable, others have a more
marked effect.

Downs syndrome:
http://kidshealth.org/parent/medical/geneti
c/down_syndrome.html#

Learners should link this change in gene structure to 17(d) and 17(q) and
to the subsequent phenotypic objective.

www.bbc.co.uk/health/physical_health/co
nditions/downssyndrome1.shtml

Learners may be shown the Downs karyotype and asked to identify how
this is different from that expected. An extension activity is to ask learners
to suggest mechanisms, based on their knowledge of meiosis, for how the
mutation may arise.

Downs karyotype:
www.slh.wisc.edu/cytogenetics/abnormalit
ies/Abn_gifs/Downs.gif

17(h)

Name radiation and chemicals as

factors that may increase the rate of
mutation

Mutagens can have the effect of altering the molecular structure of a gene
and thus altering the way in which the gene works. This may be linked to
17(g) and in turn to 17(d) and 17(q).
Learners may produce a spider diagram to show the two radiation and
chemicals as mutagens and extend this to show examples of each and
how they may be encountered in the environment.
An extension activity is for learners to research the impact of the
Chernobyl nuclear reactor incident that occurred in 1984, causing

V1 3Y08

Cambridge O Level Biology (5090)

67

Learning objectives

Suggested teaching activities

Learning resources

mutations in hundreds of people and unborn babies or of mustard gas

used in the First World War.
17(i)

Predict the results of simple crosses

with expected ratios of 3:1 and 1:1,
using the terms homozygous,
heterozygous, F1 generation and F2
generation

Learners should be encouraged to draw full genetic diagrams to show

these crosses. The diagrams should be annotated and include reference
to parents and gametes. Such diagrams demonstrate that the same
phenotype may have different genotypes.

Monohybrid inheritance animation and

activity:
www.siskiyous.edu/class/bio1/genetics/m
onohybrid_v2.html

Learners may use the suggested online learning activity to understand the
terminology and process of a monohybrid genetics cross. This may be
followed by attempting a series of teacher-set and assessed problems
covering similar scenarios.

5090 past paper question:

Nov 2011 Paper 21 Q5

It is good practice, and avoids confusion between gametes and

genotypes, if a circle is drawn around each gamete. Use of Punnett
square diagrams to illustrate the possible objectives of a genetic cross is
advised to aid clarity.
It may be beneficial to give learners practice at representing probability in
different formats (e.g. as a ratio, percentage or frequency).
Cross reference should be made to the terminology introduced in 17(e)
and 17(f).
17(j)

Explain why observed ratios often

differ from expected ratios, especially
when there are small numbers of
progeny

Learners should understand that the objective of a genetic cross is a

probability and does not refer to the genotype/phenotype of four offspring
produced.

Observed and expected ratios in Mendels

experiments:
www.siskiyous.edu/class/bio1/genetics/thr
ee_to_one_ratio.html

It should be stressed that the ratios predicted in 17(j) are statistical and
are obtained only from large samples.
Learners may use the suggested online resource to view observed and
statistical data from Mendels experiments.
A more challenging activity is for learners to produce a verbal or written
description of any differences observed.
17(k)

Explain codominance by reference to

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Learners will observe that there can be more than two alleles of the same

Cambridge O Level Biology (5090)

5090 5090 past paper question:

68

Learning objectives
the inheritance of the ABO blood
group phenotypes (A, B, AB, O,
gene alleles IA IB and Io)

Suggested teaching activities

Learning resources

gene.

Nov 2010 Paper 21 Q4

It is helpful to write down a list of the possible genotypes for blood groups
and the resulting phenotypes before attempting to draw the genetics
diagram.
A full genetics diagram may then be provided as a worked example,
following which learners may attempt similar problems to assess their
understanding.

17(l)

Describe the determination of sex in

humans (XX and XY chromosomes)

It will be necessary to point out that the sex inheritance is the result of the
inheritance of chromosomes, not of genes.
Learners may use the suggested online or text book resources, following
which they may draw a full genetics diagram to show the inheritance of
sex.

Inheritance of sex:
www.bbc.co.uk/schools/gcsebitesize/scie
nce/21c/genetics/genesinheritencerev3.sh
tml

A more challenging extension activity is for learners to produce a full

written explanation, using correct terminology, of why the probability of
male:female is 1:1 and for them to explain which parent determines a
childs sex.
17(m)

Describe variation and state that

competition leads to differential
survival of organisms, and
reproduction by those organisms
best fitted to the environment

Variation is a random process which happens to leave some members at

a survival advantage over other organisms in a particular environment. It
does not occur in order to adapt to the environment as learners often
believe. Organisms which survive then reproduce and at least some of
their offspring inherit this advantage.

Natural selection process:

http://evolution.berkeley.edu/evolibrary/art
icle/0_0_0/evo_25

Learners may use the suggested online and textbook resources to write a
numbered list of generic points outlining the process of natural selection.
Learners may then be presented with previously unseen specific
examples of where the process occurs and asked to apply their list of
generic points.
Learners may use the suggested online activity to demonstrate natural
selection in the classic example of the peppered moth.
More challenging activities that may be used to illustrate the process of

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Cambridge O Level Biology (5090)

Peppered moth simulation:

www.techapps.net/interactives/pepperMot
hs.swf
Modelling natural selection:

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Learning objectives

17(n)

Assess the importance of natural

selection as a possible mechanism
for evolution

Suggested teaching activities

Learning resources

natural selection are outlined in the modelling natural selection online

resource.

www.nuffieldfoundation.org/practicalbiology/modelling-natural-selection

An extension activity is for learners to participate in the natural selection

game outlined in the online resource.

Natural selection game:

www.biology4all.com/resources_library/so
urce/200.doc

Survival of the better-adapted organisms, each showing variations, some

of which are advantageous, generation after generation, leads to
evolutionary change in the species. Learners may cross-reference this
principle to the evolution of antibiotic resistant bacteria from 13(b) in Unit
6.

Example of antibiotic resistant bacteria:

www.windows2universe.org/cool_stuff/tou
r_evolution_9.html

Antibiotic resistance information and

animation:
www.abpischools.org.uk/page/modules/inf
ectiousdiseases_medicines/medicines3.cf
m?coSiteNavigation_allTopic=1
5090 5090 past paper question:
Nov 2011 Paper 21 Q4
17(o)

Describe the role of artificial selection

in the production of economically
important plants and animals

When humans select organisms with characteristics that are commercially

desirable and breed from them, variation can again enhance the selected
characteristic especially when repeated over many generations.

Artificial selection:
www.s-cool.co.uk/gcse/biology/geneticcrosses/revise-it/selective-breedingcrosses

Examples may include:

i. Wheat that has high-yield seed and shorter stems.
ii. Rice that has roots tolerant to lactic acid in the water.
iii. Maize bred to adapt to low carbon dioxide concs.
Learners may use the suggested online resource to select one example of
where this principle is used to research in further detail including details
of the feature(s) selected for and the commercial reasons for doing so.
17(p)

Explain that DNA controls the

production of proteins

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The linking of amino acids to form a protein in the cells of a body is

determined by DNA. The exact amino acids and their particular sequence
in each different protein are controlled by one specific gene. Cross
reference should be made to 17(e) and (g) in this unit and to 5(s) in Unit 3.

Cambridge O Level Biology (5090)

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Learning objectives

Suggested teaching activities

17(q)

State that each gene controls the

production of one protein

Each gene is a length of DNA that codes for the production of a particular
protein and may be passed from parent to offspring. Refer back to
learning objective 17(e).

17(r)

Explain that genes may be

transferred between cells (reference
should be made to transfer between
organisms of the same or different
species)

The following transfers may be included:

i. Human to human in the case of treatment for cystic fibrosis.

Learning resources

Cystic fibrosis gene therapy:

www.telegraph.co.uk/health/healthnews/4
639764/Cystic-fibrosis-sufferers-offeredhope-by-gene-therapy-treatment.html

ii. Human to bacterium (insulin production).

iii. Transfer to plant species (in the production of genetically modified
crops).
Learners may be divided into groups and each asked to research one
specific example of gene transfer. Learners may share the results of their
research in a variety of formats. Each example would include the gene
origin, gene destination, method of transfer and the nature of the
benefit(s) gained.
An extension activity is for learners to use the GM crop issues online
resource to assist them in considering the biological, social and
economical issues surrounding growing GM crops in different countries.

Information and animation of Genetic

engineering:
www.abpischools.org.uk/page/modules/ge
neng/index.cfm
GM crop production animation:
www.cfs.gov.hk/english/programme/progr
amme_gmf/programme_gmf_er_res2.html
#
Examples of GM crops:
www.bionetonline.org/english/content/ff_c
ont3.htm
Exploring GM crop issues:
www.nationalstemcentre.org.uk/elibrary/re
source/1750/talking-about-genetics

17(s)

Explain that the gene that controls

the production of human insulin can
be inserted into bacterial DNA

The insulin gene can be identified and, with the aid of enzymes, isolated
from the strand of DNA in the nucleus of a cell from a healthy person.
Enzymes are again used to attach it to the DNA of a bacterium. This
example will form one aspect included in the task set in 17(r) above.

17(t)

Understand that such genetically

engineered bacteria can be used to
produce human insulin on a
commercial scale

Culture and extraction of the insulin commercially produced should be

explained similarly to that for single cell protein and penicillin in 14(e) of
Unit 6.

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Production of human insulin:

www.abpischools.org.uk/res/coResourceI
mport/modules/hormones/enflash/geneticeng.cfm

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Learning objectives

Suggested teaching activities

Learning resources

17(u)

Learners may use the suggested online resource to prepare one side of
the argument in readiness for class debate arguing the pros and cons of
genetically engineered food.

Balanced arguments for and against GM

foods:
www.csa.com/discoveryguides/gmfood/ov
erview.php

Discuss potential advantages and

dangers of genetic engineering

The need for development of an overall balanced argument may be

stressed by asking each learner, following the class debate, to write for
the argument opposing their original position.
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