Doc Brown's Revision  KS3 Science

BIOLOGY Unit 8C Microbes and disease

KS3 Biology Quiz - 8C Microbes and diseasesQUIZ 8C on "Microbes and diseases"

What the Quiz is based on - original work schemes - programmes of study

All of KS3 Science is now under review


and the quizzes will be adapted to suit the NEW National Curriculum for KS3 Science


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About the unit

In this unit pupils:

  learn that micro-organisms share the characteristics of other living things

  find out about growing micro-organisms to make products, and about the role of micro-organisms in infectious diseases

  learn about the body’s defence systems and how immunisation can protect against microbial infections

In scientific enquiry pupils:

  consider how ideas about the transmission of infectious diseases have changed and are continuing to develop

  learn how scientists work together to investigate and reduce the transmission of infectious disease

  learn how to grow micro-organisms healthily and safely

  consider the number of measurements needed for reliable data

  identify and control relevant variables

  investigate the activity of yeast, evaluating proposed approaches

Some of this unit may be undertaken in relation to the school’s PSHE programme. Teachers will be aware of the need for sensitivity to pupils and their families who may have or have had, a particular illness or may have reduced resistance to infection.

This unit is expected to take approximately 8 hours.

Where the unit fits in

This unit draws on ideas developed in the key stage 2 programme of study. It builds on unit 6B ‘Micro-organisms’ in the key stage 2 scheme of work and on unit 8B ‘Respiration’.

In unit 9B ‘Fit and healthy’, pupils have further opportunities to consider the transmission and incidence of infectious diseases.

There are opportunities to link with citizenship and PSHE in this unit in dealing with medical advances, the development of drugs and food safety.

This unit lays the foundation for work in key stage 4 on the body’s defences against infection and the uses of micro-organisms in biotechnology.

This unit also relates to unit 9E(i) ‘Ensuring quality production (food)’ in the design and technology scheme of work, and unit 20 ‘Twentieth-century medicine’ and unit 21 ‘Scientific discoveries’ in the history scheme of work.


At the end of this unit

in terms of scientific enquiry

most pupils will: describe how understanding of how some infectious diseases are transmitted has developed as knowledge about micro-organisms has increased; point out trends and patterns in first-hand and secondary data, draw conclusions from these and relate them to scientific knowledge and understanding

some pupils will not have made so much progress and will: describe how some infectious diseases are transmitted, point out some patterns in data and use these to draw conclusions

some pupils will have progressed further and will: describe how scientists’ interpretation of evidence has led to new ideas about the transmission of disease and to new drugs

in terms of life processes and living things

most pupils will: classify bacteria, fungi and viruses as micro-organisms, name some of the diseases they can cause and describe how they can be transmitted; describe some of the defences the body has against disease and describe immunisation as a way of improving immunity; recognise that antibiotics are effective against bacteria but not against viruses

some pupils will not have made so much progress and will: name some infectious diseases and describe how they can be transmitted; describe immunisation as a way of protecting against infectious disease

some pupils will have progressed further and will: explain how immunisation can improve immunity and describe how antibiotics may be effective across a wide spectrum or against specific bacteria

Prior learning

It is helpful if pupils:

  know that micro-organisms are living organisms

  have explored the characteristics of micro-organisms and know that they feed, grow and reproduce like other organisms

  know that organisms respire aerobically and produce carbon dioxide during the process

  can name some diseases caused by micro-organisms

Health and safety

Risk assessments are required for any hazardous activity. In this unit pupils:

  plan and carry out an investigation of yeast

  grow lactobacilli and produce yoghurt

  observe the growth of bacteria and the effect of antiseptic and antibiotics

Model risk assessments used by most employers for normal science activities can be found in the publications listed in the Teacher’s guide. Teachers need to follow these as indicated in the guidance notes for the activities, and consider what modifications are needed for individual classroom situations.

Language for learning

Through the activities in this unit pupils will be able to understand, use and spell correctly:

  words and phrases relating to micro-organisms and diseases, eg bacteria, viruses, fungi, measles, chickenpox, infection, pathogen, infectious disease

  words with precise meanings in scientific contexts, eg immunity, virus, food poisoning

  words with similar but distinct meanings, eg vaccination, inoculation and immunisation, antibiotic, anti-microbial

  words and phrases relating to scientific enquiry, eg sufficient data, epidemic, reliable data

Through the activities pupils could:

  listen for a specific purpose, note the main points and consider their relevance

  organise facts/ideas/information in an appropriate sequence


Resources include:

  secondary sources, eg simulation software, CD-ROMs, illustrating the growth of micro-organisms

  datalogging equipment and software to monitor pH

  secondary sources to explore routine immunisation, ideas about side effects, immunisation in other countries

  information on routine immunisation programmes for young children

  resources to cultivate selected strains of micro-organisms

  autoclave or alternative equipment for preparation of materials and safe disposal of microbe-contaminated waste

  stock cultures of suitable micro-organisms

  secondary sources, eg photographs, advertisements, medicine packaging, relating to the nature and uses of micro-organisms

  case studies of tracking and dealing with an outbreak of an infectious disease, eg Ebola, cholera, E. coli

  data about the incidence of bacterial disease over the last 60 years

  secondary data showing the incidence over the last century of a major childhood disease for which there is now immunisation

Out-of-school learning

Pupils could:

  read leaflets on immunisation available in doctors’ surgeries

  follow news stories about outbreaks of diseases such as typhoid, dysentery or cholera after natural disasters

  visit a dairy, creamery, cheese factory, brewery

  read fiction based on epidemics, eg Siege of Krishnapur, Story of San Michele

  find out about changes in life expectancy after childbirth since 1900


 What are micro-organisms and how do we grow them?

   that there are different types of micro-organism

   that many micro-organisms are useful, eg fungi are a source of antibiotics and are used in making food products

   Use oral questions to establish what pupils know about micro-organisms.

   Provide pupils with stimulus material to explore the range of micro-organisms and their uses or occurrence, eg bread, yoghurt, wine as useful products of micro-organisms, mushrooms and other fungi, large-scale photomicrographs of bacteria and viruses, advertisements for materials which kill household germs, an empty antibiotic bottle. Provide them with additional secondary sources, eg video clips, simulation software providing further information about micro-organisms. Discuss pupils’ observations with them and help them construct a table comparing the three kinds of micro-organism.

  identify three types of micro-organism, eg bacteria, viruses, fungi

  describe the features of each of these three types of micro-organism in terms of, eg relative size, shape, structure

   Pupils learn in key stage 2 that there are micro-organisms that cause rotting and disease, and that micro-organisms are used to make foods. However, they may not have used terms such as, ‘bacteria’, ‘virus’ or ‘fungi’.


– pupils should not be allowed to eat food samples. All cultures should be sealed. Mouldy food should be sealed in plastic bags, containers or Petri dishes to ensure spores are not released


    What are micro-organisms and how do we grow them? (Cont.)

   to share ideas and information, carry out the task and then review ideas

   to decide what to measure

   how to control variables

   about the number of measurements needed for data in which they have confidence

   that yeast respires like other organisms

   to collaborate with other investigative groups to gather reliable data and draw valid conclusions

   Ask pupils what they know about yeast from advertisements they may have seen, eg yeast respiration causing bread dough to rise. Discuss with them how they could investigate how increasing the quantity of sugar affects the quantity of carbon dioxide released, eg by placing a yeast/flour/glucose dough in a measuring cylinder in a warm environment, or by collecting bubbles from a yeast/glucose suspension.

   Help pupils to plan an investigation so that together they obtain sufficient valid and reliable data.

  evaluate methods proposed and agree on a common approach

  identify variables they need to control

  work out how many measurements will be obtained and indicate whether they will have confidence in their results

  explain that carbon dioxide is produced during aerobic respiration

  collect and store reliable and valid data using the same methodology

  identify a trend in the data,
eg the more sugar is added, the greater the volume

  relate results to scientific knowledge and understanding, eg increase in volume is due to carbon dioxide produced in respiration

   Pupils may have made bread with or without yeast in key stage 2, and tried keeping yeast and sugar in a warm and in a cold place and testing the gas produced.

   The effect of sugar on yeast activity can be observed in a limited period if the yeast is fully active before starting, and the solutions are pre-warmed and quantities of materials, eg flour, glucose, are dispensed in advance. Groups of pupils will need to collaborate to obtain a sufficiently wide range of values, including repeat measurements, to draw conclusions.

   This relates to work on respiration in unit 8B ‘Respiration’.


– school-based training in aseptic techniques for staff may be necessary. All work with micro-organisms should be carried out only after appropriate risk assessments have been consulted

– pupils’ plans must be checked for health and safety before practical work begins. Ensure that plans do not involve a totally sealed system


    What are micro-organisms and how do we grow them? (Cont.)

   that bacteria can be grown

   that manufacturing processes use micro-organisms to make products

   to recognise hazards when working with living materials and to take action to avoid them

   Establish through questioning the outcomes of the yeast investigation, emphasising that carbon dioxide is produced as yeast respires aerobically and grows. Discuss with pupils ways of growing bacteria, using video clips and illustrations to demonstrate growing bacteria on agar plates, eg in a hospital laboratory.

   Demonstrate how to inoculate a nutrient agar plate, using appropriate aseptic techniques when handling micro-organisms, and help pupils to do this themselves.

   Provide pupils with reference material to find out about growing bacteria or fungi to make a product, eg yoghurt, cheese, Quorn (mycoprotein).

  use a procedure to grow micro-organisms

  describe a process which involves growing micro-organisms to make a product

  recognise hazards when working with living materials and produce information about working safely

   It takes about 24 hours to grow lactobacilli and make a pot of yoghurt, but yoghurt can be cultured in test tubes over a few hours, and changes monitored. Milk thickening, due to protein breakdown and coagulation, can be measured by timing the passage of a fixed volume through a pipette or tap funnel using refrigerated samples.

   A visit to a microbiology laboratory, bakery or creamery or a visit from a microbiologist or food scientist would enhance this unit.

   Alternative: pupils could make yoghurt using, eg different types of milk, and monitor its progress, eg by recording change in pH (using datalogging equipment) or changes in viscosity.


– yoghurt made for consump­tion should not be made in a science lab but in a food technology area


    Can micro-organisms be harmful?

   that some micro-organisms can cause disease

   that micro-organisms enter the body by a range of mechanisms

   Ask pupils how colds pass from person to person in a class. Use their answers to explain the term ‘infectious’ and introduce them to viruses as a form of pathogen.

   Discuss other infectious diseases and how they are transmitted. Provide pupils with reference sources with which to construct a table of methods of transmission, with examples of diseases and causative agents.

   Help pupils to generate a list of ways to avoid infections and then use their ideas to write a leaflet for travellers to a long-haul destination on how to avoid infection by local diseases, eg water-borne intestinal infections, malaria.

  recognise that micro-organisms can cause infections, eg food poisoning, TB, colds, tetanus, malaria, meningitis, athlete’s foot

  describe a range of mechanisms by which micro-organisms enter the body,
eg food- and water-borne, droplet/air-borne, vectors, blood-borne passage across the placenta and via breastfeeding

  produce a leaflet giving advice on avoiding infection

   Pupils may have had experiences of having immunisations for trips abroad, which can be drawn on. This should be handled sensitively for pupils whose parents do not agree with immunising children.

   Pupils may raise the issue of AIDS during this work. The school sex education, PSHE policy and guidance should be consulted.

   Extension: pupils could be asked to find out more about some current public health issues, eg the increase in tuberculosis, the increased demand for clean water in a UK city, ‘blue flag beaches’ and the factors affecting the safety of seawater.

   how a theory can be used to predict behaviour which can be tested by collecting evidence

   to listen for a specific purpose, note the main points and consider their relevance

   how scientists today tackle the spread of infectious disease

   Ask pupils to find out about an example of people preventing the spread of disease when the role of micro-organisms was not known, eg the residents of Eyam in Derbyshire restricting the spread of plague, the work of Dr John Snow identifying wells as the source of cholera infections, the work of Finlay on yellow fever.

   Invite groups of pupils to explain what was done and ask others to evaluate how effective approaches would have been in the light of knowledge about micro-organisms.

   Establish differences between some of the stories, eg John Snow’s actions were based on evidence about the distribution of cases of cholera, while the actions of others were not based on observed data. Provide pupils with information about a modern outbreak of a disease, eg Ebola, cholera,
E. coli,
and ask pupils to identify the range of people involved in containing the spread of infection. Help them to present findings, eg as a poster, flow chart.

  present information about a method of avoiding infection

  relate the methods to knowledge about micro-organisms and evaluate their effects

  describe the contributions of different scientists in dealing with an outbreak of disease

   Extension: pupils could be asked to find out about the work of Finlay on yellow fever and how his theories were only accepted once it was known that mosquitoes are carriers of malaria.


    Checking progress

   to recall key points, terms and concepts

   Provide pupils with a range of short questions, testing recall of the main types of micro-organism and their uses, the diseases they cause and how infections are transmitted from person to person. Extend for some pupils by asking questions about the ways in which understanding of infectious diseases has depended on our understanding of micro-organisms.

  show by their responses that the main points have been recalled

   Teachers may wish to point out that our understanding of the transmission of infectious diseases is by no means complete, eg the transmission of BSE.

    How can we protect ourselves against infectious diseases?

   that the body has natural barriers to infection

   that the production of antibodies and specialised cells in the blood are part of the defence systems of the body

   to listen for a specific purpose, note the main points and consider their relevance

   Explore pupils’ ideas of why people are seldom ill despite surroundings rich in potentially harmful micro-organisms by asking them to complete a concept map using a variety of terms, eg bacteria, virus, hygiene, immunity, vaccination, skin.

   Use pupils’ ideas to explain natural barriers to infection, and help pupils to annotate a diagram of the body with natural defence mechanisms. Ask pupils why young children are sometimes less resistant to infections than older children and why breastfeeding can help.

   Use video clips, ICT, slides or illustrations to show the action of white blood cells engulfing micro-organisms. Remind pupils about listening for a specific purpose and thinking about the relevance of the points made. Explain that other white blood cells make matching antibodies that identify and hinder specific microbial activity. Use the presence of antibodies in, eg blood, to link with the previous activity. Point out that all kinds of micro-organisms can cause disease and that each type of micro-organism needs a different set of antibody-making cells. Ask pupils to write a short passage about how blood cells defend against disease.

  identify natural barriers against infection, eg dry skin, lysozyme, etc in tears and sweat

  recognise that each type of micro-organism provokes a different set of antibodies

  describe how white blood cells defend the body against disease, eg engulfing micro-organisms, making antibodies

  describe antibody action,
eg marking infecting micro-organisms, entangling micro-organisms

  explain how blood cells defend against disease

   It is not necessary for pupils to learn terms such as ‘lymphocyte’ or ‘phagocyte cell’ at this stage. Further work on blood is included in key
stage 4.

   Pupils sometimes find it hard to distinguish between infectious illnesses and other forms of illness, eg dietary.

   Teachers will be aware of the need for sensitivity to the circumstances of pupils and their families who may have reduced resistance to infection.


    How can we protect ourselves against infectious diseases? (Cont.)

   that not all diseases caused by micro-organisms can easily be treated by drugs

   that some medicines contain antibiotics which kill bacteria or prevent their growth

   that scientific advances may depend on creative thought and interpretation of evidence

   Using stimulus material such as video clips, discuss with pupils how infections are treated. Identify prevention of transmission and the action of drugs to kill or suppress micro-organisms, or to relieve symptoms.

   Remind pupils of how to work safely with micro-organisms and help them to investigate the effect of common household anti-microbial compounds,
eg toothpaste, anti-perspirant, antiseptics, disinfectants, sterilising solutions, on the growth of bacteria on a nutrient agar plate. Establish that these are not antibiotics but contain agents that can kill bacteria.

   Ask pupils about medicines they cannot buy from the chemist but have to obtain on prescription, and ask them why this is so. Use their answers to explain that antibiotics kill particular bacteria and are not effective against all types of bacteria, eg neomycin sulphate against the bacteria causing middle-ear infection.

   Challenge pupils to explain why:

    people are not prescribed antibiotics when they have a cold or chickenpox

    some bacteria are resistant to antibiotics

    people are always told to complete the course of an antibiotic

    many doctors wish to limit the prescription of antibiotics

   Ask pupils to find out about the initial observation of antibiotic activity by Fleming and the further development by Florey and Chain. Provide them with data about the incidence of diseases that are treatable by antibiotics over the last century and help them to explain trends and patterns.

  show that they can work with micro-organisms safely

  describe the effect of household anti-microbial substances on bacterial growth

  state that antibiotics are effective against bacteria but ineffective against viral infections

  show in their writing that scientific advance may come from creative thought and interpretation of evidence

   Bacteria grown on a slope of nutrient agar containing disinfectant can be used to show the effects of increasing concentration of antiseptic – refer to National Council for Biotechnology Education (NCBE) publications or the Microbiology In Schools Advisory Committee (MISAC).

   Extension: pupils could observe the effect of antibiotics directly by adding discs of penicillin or streptomycin to agar plates spread with a variety of bacteria, which will show different sensitivities to the antibiotic used.

   Extension: pupils could also be asked to find out about antiviral drugs that are being developed.


– school-based training in aseptic techniques may be necessary. Employer’s risk assessments relating to work with culture plates should be fol­lowed


    How can we protect ourselves against infectious diseases? (Cont.)

   that immunisation helps to protect against some diseases

   that antibodies can pass through the placenta to the foetus and through breast milk to a baby

   that vaccines contain material which stimulates body defences

   Ask pupils about which immunisations they have had, eg polio, DPT (diphtheria/whooping cough/tetanus), MMR (measles/mumps/rubella), HIB (Haemophilus influenzae B), Heaf tests and TB (tuberculosis), and why they had them.

   Explain what is in a vaccine. Show, by using charts, video clips and simulation software, what happens to antibody levels in the blood as the programme of immunisation proceeds. Challenge pupils to predict what happens in the blood when someone re-encounters the micro-organisms against which they have been immunised. Ask pupils to annotate a graph of antibody changes in the blood after, eg DPT, immunisations. Explain that antibodies pass to babies via breast milk and play an important role in protecting newborn babies from disease.

  explain ‘immune’ as meaning resistant to disease and that immunisation is a way of raising immunity

  recall that vaccines contain microbial material, eg weakened strains, dead micro-organisms, extracts of micro-organisms, that cannot cause infections

  explain that antibodies pass to a baby across the placenta and via breast milk

  explain that immunisation protects the body against some diseases because antibodies are made more quickly in response to infection

   It is useful to have a box of information snippets for research, eg measles immunisation required for entry to US schools, World Health Organization programmes, newspaper clippings about vaccine scares, comparative data on the incidence of measles and ensuing complications in developed and developing countries.

   to identify patterns in data from secondary sources and to try to explain them

   to organise facts/ideas/ information in an appropriate sequence

   Provide pupils with secondary data on the incidence of a major childhood disease, eg diphtheria from 1910 to 1955 in a city location. Ask them to relate patterns to the introduction of immunisation and the start of a free health service.

   Ask pupils to find out about programmes of routine immunisations using reference materials, ICT and the internet. Use the information to write a magazine article about the advantages and disadvantages of routine immunisations.

  describe how the incidence of, eg diphtheria, varied over the period and relate changes to social changes, eg the introduction of immunisation

  present a point of view in writing, using statistical evidence and linking points persuasively

   Statistics on disease incidence are available in government reports such as those of the chief medical officer, available from HMSO bookshops.

   Some teachers may want to go further and discuss why some immunisations need boosters every few years, eg against tetanus, while others, eg against cholera, are not very effective.  The relationship between the incidence of infectious disease and other factors, eg diet, is explored further in unit 9B ‘Fit and healthy’.


     Reviewing work

   to collate ideas about micro-organisms, diseases and defences against disease

   to identify key points about micro-organisms and their relationship to disease

   Ask pupils to produce a concept map of micro-organisms and diseases using the terms in this unit. Using their concept maps they can generate a list of questions to ask each other about micro-organisms.

   Ask pupils to go through the work they have done in this unit and pick out five or six key points, and then in groups agree ten amongst themselves. Compare the lists of different groups and agree a summary of key points with the class, in which closely related points are grouped together.

  demonstrate, by their responses, understanding and recall of key points

  identify, summarise and group key points


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