AS and A LEVEL
Delivery Guide
H022/H422
BIOLOGY B
(ADVANCING BIOLOGY)
Theme: Pathogenic
microorganisms 3.2.1
October 2015
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AS and A LEVEL
BIOLOGY B (ADVANCING BIOLOGY)
CONTENTS
Introduction Page 4
Curriculum ContentPage 5
Thinking ConceptuallyPage 9
Thinking ContextuallyPage 14
Learner ResourcesPage 17
Teacher ResourcesPage 18
3
Introduction
KEY
Delivery guides are designed to represent a body of
knowledge about teaching a particular topic and contain:
• Content: a clear outline of the content covered by the
delivery guide;
• Thinking Conceptually: expert guidance on the key
concepts involved, common difficulties students may
have, approaches to teaching that can help students
understand these concepts and how this topic links
conceptually to other areas of the subject;
• Thinking Contextually: a range of suggested teaching
activities using a variety of themes so that different
activities can be selected that best suit particular classes,
learning styles or teaching approaches.
Click to view associated resources
within this document.
Click to view external resources
A Level content only
If you have any feedback on this Delivery Guide or
suggestions for other resources you would like OCR to
develop, please email [email protected].
4
Curriculum Content
Pathogenic microorganisms 3.2.1
(a)
how pathogens (including bacteria, viruses and fungi)
cause communicable disease
To include an outline of the general mechanisms of pathogenicity
by bacteria (toxin production), viruses (taking over cell metabolism)
and fungi (enzyme secretion).
(b)
the causes, means of transmission, symptoms and the
principal treatment of tuberculosis (TB) and HIV/AIDS
To include droplet infection, details of primary and secondary TB
and also opportunistic infections (HIV-AIDS).
HSW10
(c)
the structure of the Human Immunodeficiency Virus (HIV)
(d)
(i) the use of Gram stain, cell and colony morphology to
identify bacteria
To include the use of diagrams showing the location of enzymes
and the nature of the genetic material.
(ii) the culturing of bacteria and the identification of
Gram-positive and Gram-negative bacteria using the
Gram staining method on pure cultures
HSW3, HSW4, HSW5, HSW6, HSW8
(e)
how the incidence and prevalence of a communicable
disease can change over time
To include the principles of endemic communicable diseases (e.g.
chickenpox in the UK), epidemics (e.g. SARS in China, 2002) and
pandemics (e.g. H1N1 influenza in 2009).
(f)
calculations of incidence rates, prevalence rates and
mortality rates and their importance in epidemiology
M0.1, M0.3, M0.4
(g)
the analysis, interpretation and use of epidemiological
data
To include the evaluation of graphical data to assess the impact of
disease e.g. for HIV and TB infection.
M1.3, M1.7, M3.1, M3.5, M3.6
HSW12
5
Curriculum Content
(h)
(i)
the importance of reporting notifiable diseases and
the role of Public Health England (formerly the Health
Protection Agency (HPA))
To include examples of notifiable diseases.
the social, ethical, economic and biological factors
involved in the attempts to control and prevent diseases
in the context of HIV/AIDS and TB.
HSW10
HSW12
Significant advances in controlling the spread of pathogens have been made throughout the last decade but the answers to
eradicating diseases such as HIV and tuberculosis have proved elusive.
This topic provides a number of specific challenges for teachers. These include:
•
•
•
•
•
helping students to perceive sequences of events at the cellular and molecular level in what are likely to be very abstract
concepts
overcoming students’ aversion to graphical and tabular data analysis, along with the associated mathematical calculations
evoking in students a balanced view of the social, ethical, economic and biological factors that affect disease control
being aware of misconceptions students may have towards diseases such as HIV
making students aware of the range of different pathogenic organisms and trying to emphasize their effect on what is regarded
as ‘illness’.
6
Curriculum Content
Activities
Resources
Gram staining activity
http://www.brainpop.com/games/virtuallabsgramstaining/
Click here
BrainPOP provide a virtual lab where students can carry out Gram staining online to test a contaminated yogurt sample.
Students can practise Gram staining either as a preparatory homework or lesson starter to allow them to practise the steps
required for the procedure. This could be used for students to plan their own method prior to carrying out the procedure.
Types of pathogen
http://www.abpischools.org.uk/page/modules/infectiousdiseases_pathogens/pathogens8.cfm?coSiteNavigation_allTopic=1
Click here
General descriptions of pathogens including bacteria and viruses are explained. This is then linked to how the body prevents
the transmission of the pathogen. Further information on types of pathogen are explained in the second resource:
http://www.abpischools.org.uk/page/modules/diseases/diseases1.cfm
Click here
The third resource provides a more in-depth description of types of pathogen and may be more suitable for more able
students:
https://science.education.nih.gov/supplements/nih1/Diseases/guide/understanding1.html
Click here
Students could be split into groups, with each group focusing on one type of pathogen. They could then present their
findings to the class, and summarise the findings on each type of pathogen.
HIV structure
http://www.nhs.uk/conditions/HIV/Pages/Introduction.aspx#close
Click here
The NHS provides information on HIV that, if utilised online, allows students to use hyperlinks for more information, if needed.
Students could summarise key topic areas such as the symptoms, causes, diagnosis, treatments, prevention and living
with HIV.
7
Curriculum Content
Activities
Resources
HIV and TB Prevalence
https://www.koshland-science-museum.org/sites/all/exhibits/exhib_infectious/global_distribution.jsp
Click here
Koshland science museum provides a clear map showing global distributions of HIV and TB prevalence.
Students can use this as a basis to start considering the reasons why HIV prevalence and TB prevalence are highest in and
around the African continent.
This is a good opportunity to consider correlation and causation. Is there any correlation between TB and HIV distribution?
Can we suggest a causative relationship based on our knowledge of these diseases? How could we go about producing
evidence that might support or contradict our ideas? Do our suggestions for evidence gathering have ethical, economic or
risk aspects to consider before embarking on such research for real?
Click here
These two resources can then be used to produce poster displays, or as part of a discussion as to how HIV and TB spread and
what could be done to control it.
Click here
http://www.aids.gov/hiv-aids-basics/hiv-aids-101/how-you-get-hiv-aids/
http://www.aids.gov/hiv-aids-basics/staying-healthy-with-hiv-aids/potential-related-health-problems/tuberculosis/
The emerging threat and challenges of HIV
University College London provide a fantastic 12-minute video clip, giving a brief overview of the history of HIV and
explaining many of the reasons why the spread of HIV is not easy to control.
Click here
https://www.youtube.com/watch?v=k-BRZ7PezH4
A shorter three minute clip briefly describes the challenges of HIV. These could be used as a fantastic introduction to start the
topic off and stimulate discussion around HIV.
https://www.youtube.com/watch?v=tcCSnR9hoOE
8
Click here
Thinking Conceptually
Approaches to teaching the content
• Conceptual route
• Analytical route
The conceptual and analytical routes highlight the distinctions between two very different types of content: the technical detail
of epidemiology and its causal agents, and the application of judgements about data. Detail, precision and rigour are necessary
to fully understand the processes, but imagination and maturity are necessary to appreciate the applications and their relevance
to society. Freedom to innovate and explore are encouraged in the interactive contextual resources provided.
Conceptual route
This builds up from the molecular structure of different pathogens, putting them into context and then demonstrating their
effects globally in a graphical form. It would suit able students with a good background in molecular biology and an ability to
clearly sequence actions.
Teaching aims content outline
3.2.1
revision of RNA structure
2.1.4 (f )
revision of transcription
2.1.4 (g)
the structure of the Human Immunodeficiency Virus (HIV)
(c)
revision of prokaryotic cell structure
2.1.1 (h)(i)
the use of Gram stain, cell and colony morphology to identify bacteria
(d)(i)
the culturing of bacteria and the identification of Gram-positive and Gram-negative bacteria using the Gram
staining method on pure cultures
(d)(ii)
how pathogens (including bacteria, viruses and fungi) cause communicable disease
(a)
revision of the role of a cell surface membrane in cell recognition
2.1.1 (n)
the causes, means of transmission, symptoms and the principal treatment of tuberculosis (TB) and HIV/AIDS
(b)
the importance of reporting notifiable diseases and the role of Public Health England
(h)
the social, ethical, economic and biological factors involved in the attempts to control and prevent diseases in the
context of HIV/AIDS and TB
(i)
calculations of incidence rates, prevalence rates and mortality rates and their importance in epidemiology
(f )
how the incidence and prevalence of a communicable disease can change over time
(e)
the analysis, interpretation and use of epidemiological data
(g)
9
Thinking Conceptually
Analytical route
This route starts by identifying patterns and trends in epidemiological data that impact on society, and building on it to
highlight the importance of accurate recording of disease, before focusing on the pathogens themselves.
It would suit students with a mathematical background, who are more likely to engage if data can be extrapolated to put the
subject material into context. Resources from the World Health Organization and the NHS websites can be used to generate
discussion and identify trends in the spread of communicable diseases.
Teaching aims content outline
3.2.1
calculations of incidence rates, prevalence rates and mortality rates and their importance in epidemiology
(f )
the analysis, interpretation and use of epidemiological data
(g)
how the incidence and prevalence of a communicable disease can change over time
(e)
the importance of reporting notifiable diseases and the role of Public Health England
(h)
the social, ethical, economic and biological factors involved in the attempts to control and prevent diseases in the
context of HIV/AIDS and TB
(i)
revision of prokaryotic cell structure
2.1.1 (h)(i)
how pathogens (including bacteria, viruses and fungi) cause communicable disease
(a)
revision of RNA structure
2.1.4 (f )
revision of transcription
2.1.4 (g)
the structure of the Human Immunodeficiency Virus (HIV)
(c)
the use of Gram stain, cell and colony morphology to identify bacteria
(d)(i)
the culturing of bacteria and the identification of Gram-positive and Gram-negative bacteria using the Gram
staining method on pure cultures
(d)(ii)
revision of the role of a cell surface membrane in cell recognition
2.1.1 (n)
the causes, means of transmission, symptoms and the principal treatment of tuberculosis (TB) and HIV/AIDS
(b)
10
Thinking Conceptually
Common misconceptions or difficulties students may have
Understanding the complexity of epidemiology and the mode of action of pathogens are made much simpler if students have
a strong analytical and evaluative skill, as well as a firm grasp of cellular biology.
The analytical and evaluative requirement of data analysis often finds students unprepared in exams. It is important that
students have a clear understanding of how command words such as describe, explain and suggest are used in relation to
epidemiological evidence.
The other major difficulty students encounter is not appreciating how the structure of a pathogen relates to its method of
transmission. This is specifically addressed in both teaching routes set out above.
Conceptual links to other areas of the specification – useful ways to approach this topic to set students up for topics
later in the course
Teaching of this topic should be firmly bedded in an understanding of the action of pathogenic organisms in causing
communicable disease and interpreting epidemiological data, so a secure grasp of the prokaryotic cell structure (2.2.1 (h)
(i)), the structure of RNA (2.1.4 (f )) and a knowledge of transcription (2.1.4 (g)) are also needed. A solid knowledge of practical
skills in the written examination, particularly those relating to analysis of data (1.1.3) and evaluation of data (1.1.4) are essential.
Mathematical skills will be assessed throughout the module and will include, but are not limited to, M0.1, M0.3, M0.4, M1.3, M1.7,
M3.1, and M3.5.
The concepts learned in 3.2.1 are relevant to the following areas of the syllabus and a link could be made back to the older topic
and the 3.2.1 material re-introduced in the later topics in order to prepare students for synoptic questions:
• 3.2.3 (b) the role of vaccination programmes in the prevention of epidemics
• 3.2.3 (c) the biological problems in the development of vaccines and the use of vaccination programmes
• 3.2.3 (g) practical investigations on the effect of antibiotics on Gram-positive and Gram-negative bacteria.
For A Level students only:
•
•
•
•
4.3.2 (a) the factors that alter the birth rate and death rate in human populations
5.1.1 (b) gene mutations
5.1.2 (a) the role of natural selection in changing the allele frequencies within populations
5.1.2 (b) the link between the changes in the amino acid sequence to the change in structure and properties of proteins.
11
Thinking Conceptually
Activities
Resources
Incidence
This resource gives a comprehensive overview of the H1N1 strain of flu and how the incidence of the disease is changing.
Click here
http://bigpictureeducation.com/sites/default/files/bp_files/influenza%20special%20edition/wtdv026878~4.pdf
Students can use the resource to produce a newspaper article explaining how diseases such as flu can reach pandemic
proportions.
Analysis of TB and HIV data
The following resources show the incidence of tuberculosis and prevalence HIV.
TB:
http://www.tbfacts.org/tb-statistics.html
Click here
A useful introduction to the terms, incidence and prevalence, along with some facts and figures.
The following two sites contain a wealth of data, which will look rather dry and overwhelming at first. However, it is useful for
students to get used to being presented with data and challenged to pull out salient features or summarise what it shows:
Click here
http://data.worldbank.org/indicator/SH.TBS.INCD/countries
https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/376647/Worldwide_TB_Surveillance_2013_
Data_.pdf
Click here
HIV prevalence:
http://www.who.int/gho/hiv/en/
Together, these can be used in groups to formulate discussion around describing, explaining and suggesting reasons for the
trends.
Click here
The following resource may be of use to students to help with understanding how to analyse data.
http://bigpictureeducation.com/number-crunching
Click here
12
Thinking Conceptually
Activities
Resources
Notifiable disease
The following resource is the government guidance on the reporting of notifiable diseases and causative organisms.
https://www.gov.uk/notifiable-diseases-and-causative-organisms-how-to-report
Click here
Students could produce an NHS style information leaflet for the distribution to GP surgeries and walk-in centre advising staff on
how and why notifiable disease are reported.
Factors in controlling the spread of TB and HIV
The following resources are from CDC, the Centers for Disease Control and Prevention. They allow students to investigate all
aspects of the social, ethical, economic and biological factors involved with disease control.
Click here
http://www.cdc.gov/tb/
http://www.cdc.gov/hiv/
Students could be divided into groups and each group asked to research one aspect of social, ethical, economic and biological
control for either TB or HIV before delivering their findings in a presentation, or communicating their finding through a ‘market
place’ activity.
Click here
If time is limited, the following resource could be used as it gives a concise overview of the control measures.
Click here
http://www.biologicalcontrols.com/nlca.shtml
13
Thinking Contextually
Activities
Resources
HIV fact file
The first link below is to a factsheet that gives students a comprehensive description of the problem that HIV poses by
thoroughly explaining the symptoms, mode of transmission, treatments, methods of prevention and control.
Click here
http://www.who.int/mediacentre/factsheets/fs360/en/
Suggested activities:
Learner Resource 1 can be used as a quick knowledge check and consolidation and to initiate debate.
Alternatively, or leading on from that, students can build on Learner Resource 1 (there is plenty more to find out about each
question over and above the brief teacher notes) to produce an information leaflet that could be handed out to the general
public in the UK. The leaflet should be simple enough to get the points across but still explain a comprehensive range of
control measures.
Learner
Resource
1
The next link includes an article explaining a programme aimed at reducing mother-to-child transmission of HIV in Swaziland.
It gives details of how efforts have been made in the programme to control the spread of the disease.
http://www.who.int/features/2012/pmtct_swaziland/en/
This could be used as a basis from which students can discuss the pros and cons of a programme aimed at reducing
breastfeeding in a country where poor sanitation and a lack of water chlorination lead to many deaths.
A brief introduction to HIV
This short video clip can be used as a starting point for students to begin developing their ideas about HIV. After watching
the video, the students could discuss their ideas about HIV and record their initial thoughts. They could then embark on a
research task on HIV before revisiting their initial thoughts and writing a reflective log of what they have found.
https://www.youtube.com/watch?v=rv0yIICeg-E
14
Click here
Click here
Thinking Contextually
Activities
Resources
TB fact file
This resource gives students a range of resources that can be used to give a comprehensive description of the problem that
tuberculosis poses:
Click here
http://www.who.int/tb/en/
This resource includes data on tuberculosis cases:
Click here
http://www.who.int/tb/country/en/
Thsi site has factsheets on the disease:
http://www.who.int/tb/publications/factsheets/en/
Click here
An animation on the transmission may be of benefit to visual learners:
http://www.wellcome.ac.uk/Education-resources/Education-and-learning/Resources/Animation/WTDV026681.htm
These resources can be used to produce an information leaflet that could be handed out to the general public in the UK. The
resource should be simple enough to get the points across but still explain a comprehensive range of control measures.
Click here
HIV structure
The structure of the HIV is explained in a narrated or step through format. The mode of action is explained along with the
stages of the process that are targeted in the treatment of HIV.
http://highered.mheducation.com/sites/0072495855/student_view0/chapter24/animation__how_the_hiv_infection_cycle_
works.html
There is an option to have the animation narrated so it can be used in class for teaching or by individual students with access
to a computer in a class or private study setting. The resource has questions to assess learning at the end of the animation.
Accompanying activities could involve written summaries or translating the information into another form such as a flow
chart to cement learning and understanding.
15
Click here
Thinking
ThinkingContextually
Contextually
Activities
Resources
Carrying out Gram staining
Laboratory applications in microbiology provide a step by step animation showing the steps of gram staining. If used online
the students can test themselves using the ‘test yourself’ questions that follow the animation.
Click here
http://highered.mheducation.com/sites/0073402370/student_view0/exercise9/gram_stain.html
A more detailed video tutorial can be used, if the students are to be guided through the practical step-by-step:
https://www.wisc-online.com/learn/career-clusters/health-science/mby4808/gram-stain-procedure
These resources can be used by the students to plan their own investigation into Gram staining, allowing them to address
HSW3, HSW4, HSW5, HSW 6 and HSW8.
16
Click here
Learner Resource 1 So you think you know the truth about HIV?
See
page 14
For each of the statements below, tick if you think the statement is true, you don’t know or you think it is false.
No.
Statement
True
1
HIV and AIDS are the same thing
2
Homosexual men are the most likely to suffer from HIV
3
HIV cannot kill you
4
HIV cannot be contracted by kissing
5
If treated early enough, AIDS is no longer considered a fatal disease
6
Mothers who are suspected of being HIV positive have the right to not be tested for the disease, even if the developing fetus may be affected
7
If you have ever had an HIV test, you can still get medical insurance or life insurance
8
Employees have to tell their employers if they have HIV
9
HIV came from monkeys
10
HIV sufferers cannot play contact sport
17
Don’t know
False
Teacher Resource 1 So you think you know the truth about HIV?
For each of the statements below tick if you think the statement is true, you don’t know or you think it is false.
No.
Statement
True
HIV and Aids are the same thing
1
3
4
5
6
7
8
9
HIV destroys T-helper cells (CD4+ T lymphocytes) and as a result weakens the immune system.
HIV cannot be contracted by kissing
Theoretically possible as the virus is found in saliva but never actually proven to be contracted by kissing.
If treated early enough, AIDS is no longer considered a fatal disease
Providing there are no problems with drug resistant strains, the individual could live a very long time.
Mothers who are suspected of being HIV positive have the right to not be tested for the disease, even if the developing fetus may be affected
Although almost all mothers do have a routine HIV blood test as part of the pre-natal tests, a mother can opt out if she wants.
If you have ever had an HIV test, you can still get medical insurance or life insurance
Insurance companies are not allowed to discriminate against people for having a test even if their lifestyle still puts them at risk.





Employees have to tell their employers if they have HIV

Only if you have a role in which you carry out ‘exposure-prone procedures’.
HIV came from monkeys
It is widely accepted that the HIV virus came from primates (probably during the 19th or 20th century).
HIV sufferers cannot play contact sport
10

Globally HIV is most common in heterosexual individuals. The pattern in particular countries can vary. In the UK, HIV prevalence is higher
amongst homosexual men than the average across the whole population.
HIV cannot kill you
False

HIV is the name of the virus. AIDS is when someone is infected with HIV and either i) has an ‘opportunistic’ disease such as TB or ii) has a
compromised immune system (low CD4+ T-cell count).
Homosexual men are the most likely to suffer from HIV
2
Don’t know
‘Blood-to-blood’ contact, which is how the virus might be passed on, is very unlikely. There are no known cases of anyone contracting HIV
through sport. Only in boxing are competitors banned from fighting .
18


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