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					                            9.4 SEARCH FOR BETTER HEALTH (booklet)
                                                         (Last updated 5th May 2011 by SR/IR)


1. What is a healthy organism?

What is meant by the term disease?

Background: Disease is any condition that adversely affects the function of any part of a living thing. Health is the wellbeing of the
organism. All our body functions, which are under the control of our genes, work together to maintain health.


Discuss the difficulties of defining the terms 'health' and 'disease'

        The definition of disease above is very broad. Disease can cover a wide range of conditions that fit the above definition including
         minor conditions, such as a cut finger or an ant bite, as well as the more obvious diseases.
        Health varies on a daily basis and is not just the absence of disease. Health varies with age and the susceptibility to disease. It is
         a state of physical, mental and social wellbeing.
        The difficulties of defining the terms health and disease include that:
              o it is possible for a person to be healthy and have a disease at the same time
              o the terms are used in general conversation and have different meaning to the scientific definition.

Use available evidence to analyse the links between gene expression and maintenance and repair of body tissue

        Gene expression refers to the transfer of information from a gene to produce a protein or RNA. If you cut yourself, the genetic
         code contained in all your cells is used to form the new tissue to repair the damage from the cut.
        Analyse the information by identifying cause and effect relationships between gene expression and the maintenance and repair
         of body tissue.

         Consider, that if a certain gene expresses, what the effect will be on:

              o    regulation of the cell cycle
              o    mitosis
              o    protein synthesis.

        Use the information you have gathered to synthesise an account of the connection between gene expression and the
         maintenance of healthy tissue.

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Outline how the function of genes, mitosis, cell differentiation and specialisation assist in the maintenance of health

Gene expression is essential for the maintenance of health.

        Genes are the units of inheritance. They control the process of protein synthesis. They assist the maintenance of health by
         regulating the cell cycle and limiting the growth and reproduction of cells. Genes provide the code for proteins that are needed
         for growth and repair. Enzymes, which control all body processes, are proteins and thus have been produced from the codes of
         genes.
        Mitosis is cell division that produces identical cells. These cells are important for growth and reproduction. Each day millions of
         cells die and are replaced by the process of mitosis.
        Cell differentiation is the process undergone by the cells that are formed after mitosis. Each cell has the genetic information
         necessary to produce all types of cells. However, each cell normally differentiates to become a specialised cell, with a
         specialised structure and function. Undifferentiated cells form tumours.
        Many types of cells have specialised roles in maintaining the health of an organism. For example, there are specialised blood
         cells that produce antibodies to attack a disease causing micro-organism.
2. Infectious and non-infectious diseases

2. Over 3000 years ago the Chinese and Hebrews were advocating cleanliness in food, water and personal hygiene

Background: Even though they did not know about microscopic disease-causing organisms, many social groups established rules and
practices that protected people against infectious diseases. These practices resulted from observing cause and effect relationships. For
example, the Chinese could have deduced the connection between water contaminated by faeces and gastro-intestinal diseases, and the
Hebrews may well have made a connection between the symptoms of infection by tapeworms and eating undercooked pork.

Distinguish between infectious and non-infectious disease

        An infectious disease is one that is caused by an organism and that can be transferred from one person to another. The transfer
         may be direct, where the disease-causing organisms, such as viruses or bacteria, pass directly from person to person, or it may
         be carried out by an intermediary (called a vector), such as a blood-sucking insect. Examples of infectious diseases are colds,
         influenza, chicken pox, herpes and measles.
        Non-infectious diseases are diseases that are not due to disease-causing organisms. They include genetic diseases, such as
         Down syndrome, haemophilia, and those that are related to lifestyle or environment, such as cardiovascular disease and skin
         cancer.

Identify data sources, plan and choose equipment or resources to perform a first hand investigation to identify microbes in food
or in water

        Agar is a jelly-like substance obtained from seaweed. When it is dissolved in water, nutrients suitable for microbes can be added
         to it before it sets to form a gel. If a microbe makes contact with the agar and if conditions are suitable, the microbe will grow
         and reproduce to form a visible colony.
        To design a first-hand investigation to identify microbes in food and water, firstly identify data about microbiological techniques
         from practical manuals or the Internet. Gather information about the techniques used to grow micro-organisms on agar plates
         in Petri dishes. You will need to know what sort of nutrients can be added to agar, the correct way of exposing the agar to the
         source of micro-organisms and the safety precautions that must be followed once a plate has been exposed. Also you will need
         to know the best temperature for microbial growth and how to distinguish between colonies of bacteria and fungi, growing on
         agar plates.
        Use the information to plan a valid and reliable investigation. You will need to decide on which nutrients you will add to the
         agar, what food and water samples you will test and how you will expose the agar to the microbes that may be present in your
         food and water samples. Decide on the temperature you will provide for microbial growth.
        Choose equipment and resources that will ensure your investigation is safe. Carry out a risk assessment of your experimental
         procedures and address potential hazards. In this type of investigation, the most important safety procedures are:
               o to seal and not open again the Petri dishes after exposure
               o to correctly autoclave exposed Petri dishes prior to final disposal.
        Perform your investigation. Dispose carefully and safely of the waste materials produced during the investigation. Safe working
         practices such as wearing latex gloves, washing benches and hands with chemical treatments for sterilisation are important
         when working with micro-organisms.
         Use data from the investigation to explain why cleanliness in food, water and personal hygiene practices are important.

Explain why cleanliness in food, water and personal hygiene practices assist in the control of disease

        There are huge numbers of disease causing organisms. Most of them are microscopic and can enter the body through any body
         opening. The intake of food and water provide an easy way for micro-organisms to enter our bodies. Therefore, minimising the
         number of such organisms in our food and water reduces the risk of infection. Good personal hygiene ensures that body
         openings, including broken skin, are clean, so that the number of micro-organisms that might gain entry to our bodies is kept
         low. Since we cannot see individual micro-organisms we take precautions that we know will help to protect us. Examples of
         precautions include, washing hands after going to the toilet, cleaning wounds, boiling water and water treatment of water that
         doesn't come from a known safe source to make sure untreated sewage does not get into food or water supplies.
Identify the conditions under which an organism is described as a pathogen

        A pathogen is any organism that can produce a disease. Pathogens range from viruses so small that thousands will fit side by
         side in one millimetre to tapeworms that can be several metres long. They are all infectious.
        Pathogens may live outside the body, such as the fungus that causes ringworm, inside particular organs, such as parasitic
         worms in the intestine, in tissues or inside cells. Some information on water pathogens is found below.

Gather, process and analyse information from secondary sources to describe ways in which drinking water can be treated and
use available evidence to explain how these methods reduce the risk of infection from pathogens

Contamination of drinking water is a common way for pathogens to enter the body.

        Gather information from your local water supply authority or the Internet to find out the ways in which water can be treated and
         the range of pathogens that are targeted.
        Process your information by recording a description of each water treatment method and by looking for trends and patterns in
         why they are used.

         Information to get you started

         Examples of water treatments are filtration, chlorination and ozone filtration. In NSW water is filtered, chlorine is added to kill
         bacteria and samples are tested for the presence of coliform bacteria, giardia and cryptosporidium.

         Use questions as an effective processing technique to focus your attention when looking for trends in information sources. Some
         examples in this case might be “Which microbes are controlled by the treatment?”, “Which microbes are not controlled by the
         treatment?” and “What combination of treatments can be used to make a water supply safe for drinking?”

        Use the evidence you have gathered to propose logical explanations of how each form of water treatment protects people from
         the target pathogens.
3. Identifying microbes that cause disease

3. During the second half of the nineteenth century, the work of Pasteur and Koch and other scientists stimulated the search for
microbes as causes of disease

Background: Microbes as the cause of infectious disease:
     Until mid 19th century, spontaneous generation believed origin of living things.
     Derived from non-living matter.
     680, Francesco Redi disproved spontaneous generation.
     Scientists refused to accept his results.
     Belief of spontaneous generation remained.
     Prevented people understanding causes of disease & transmission.


Describe the contribution of Pasteur and Koch to our understanding of infectious diseases

Louis Pasteur

        The role of Pasteur in identifying the causes of disease was:
              o that he disproved the theory of spontaneous generation, which was widely held at the time. Before Pasteur's work,
                   people believed that maggots and fungi grew naturally from non-living material
              o that he showed that micro-organisms came from pre-existing micro-organisms.
              o Discovered germ theory of disease:
              o Most infectious diseases caused by micro-organisms or germs.
              o Examined fermented wines under microscope.
              o Described micro-organisms growing.
              o Demonstrations of living organisms existing in air destroy theory of spontaneous generation.
                                                                       o
              o Showed French wine industry that heating wine to 55 C destroyed microorganisms.
              o Pasteurisation - Now applied to:

                         Beer;
                         Milk.

                o Founded vaccination.
                    Inoculated 25 sheep with weakened Bacillus anthracis (anthrax bacteria);
                    Injected 50 sheep with strong dose of anthrax;
                    Predicted 25 would die;
                    25 inoculated sheep survived.
                    Developed vaccination for – Anthrax, Chicken cholera, Swine erysipelas.
                    Developed rabies vaccination in 1885, saved life of infected boy.

Robert Koch

        About 150 years ago, Pasteur's work in identifying, under the microscope, the organism that caused fermentation, led some
         people to suggest the infectious diseases were caused by microscopic pathogens. Others argued that bacteria found in sick
         animals followed the infection, rather than causing it.
        The work of Robert Koch (1843 - 1910) provided the proof that was needed to convince people that microscopic pathogens cause
         disease. His first experiments were with the disease anthrax in sheep. Later, he obtained similar results for tuberculosis and
         cholera.
        First Koch found bacteria in sheep infected with anthrax. Then, he placed the bacteria on agar plates in Petri dishes so that many
         colonies of the bacteria were produced. He used bacteria from these colonies to infect healthy sheep and found that they
         became infected.
       After his experiments with anthrax, Koch was able to state a series of steps that are needed to identify the micro-organism
        responsible for a particular disease. These steps are called Koch's postulates.
             o Step 1: All infected hosts must contain the suspect organism.
             o Step 2: A pure culture of the suspect organism must be obtained.
             o Step 3: A healthy organism infected with the pure culture must have the same symptoms as the original host.
             o Step 4: The suspect organism must be isolated from the second host, grown in pure culture and prove to be identical to
                  the first culture.
       Koch's postulates can be used to identify the causative organism of an infectious disease. The symptoms of the disease are
        carefully identified and then the blood of sufferers is examined to determine possible causative organisms. A particular micro-
        organism will be suspected if other sufferers have the same micro-organism present in their blood and a mechanism can be
        identified to allow transfer of the micro-organism. Identification of the organism in more sufferers will confirm the causative
        organism. Sometimes, a suspected causative organism can be confirmed by infecting a test organism.

Perform an investigation to model Pasteur's experiment to identify the role of microbes in decay

       Perform Pasteur's experiment that showed that something from the air causes meat broth to go bad. As you conduct your
        experiment consider which variables need to be kept constant and be able to explain which are the dependent and which are
        independent variables.

        Procedure:

            1. Use a meat extract cube to make a clear broth.
            2. Use two conical flasks instead of Pasteur's balloon flasks. Fit the flasks with one-holed stoppers. Use glass tubing bent
                 into an S-shape to replace Pasteur's swan-necked flask. Place a straight piece of glass tubing in the other flask.
            3. Put some broth into both flasks and boil gently for fifteen minutes.
            4. Leave both flasks, not in direct sunlight for several weeks. Every two or three days compare the contents of the two
                 flasks. Look for cloudiness, scum, bubbles and mould colonies. Record your results.
       Assess the accuracy of your observation and the relative importance of the data gathered. You could do this by comparing your
        experiment with the description of Pasteur's experiment, which follows.

Pasteur's experiment

       When Pasteur did his experiment, the broth in the swan-necked flask remained clear for several weeks, while that in the open
        flask quickly became cloudy and smelly.
       Both flasks were open to the air. In the swan-necked flask, air could move freely through the neck of the flask just as it did in the
        straight-necked flask, but the much heavier micro-organisms, in the air, were trapped in the bottom part of the S-curve.
       This experiment showed that for the broth to grow micro-organisms and start to decay, there had to be access to air containing
        the spores of micro-organisms.
Gather and process information to trace the historical development of our understanding of the cause and prevention of
malaria

Background on malaria

Malaria is a disease caused by a protozoan of the genus Plasmodium. It has a complicated life cycle requiring a mosquito of the Anopheles
genus to carry the Plasmodium to its host. The disease is common in tropical areas where the Anopheles mosquito lives. The female
mosquito requires a blood meal to complete the reproduction cycle of the mosquito. During the blood meal the Plasmodium (sporozoites)
are transferred from the mosquito salivary glands into the blood system of the host. The sporozoites travel to the liver via the blood
system and enter cells in the liver. After 12 days a new form of the protozoan called merozoites are released and these enter blood cells.
At the same time toxins are released. This causes the sweats and fever that are associated with the disease. Some of the merozoites
develop into gametocytes and may be sucked up by another mosquito in another blood meal. In the gut of the female mosquito the
gametocytes become gametes and are fertilised. This forms sporozoites which will travel to the salivary glands of the female mosquito
and await the next blood meal to enter another host.

The disease was known from the start of recorded history but it took many researchers to uncover the complicated life cycle above. Sir
Ronald Ross (1857 - 1932) was a British medical officer working in India. For thousands of years, people had been puzzled about the way in
which malaria spread but they knew that malaria was common in areas close to swampy land. In the late 1800s, people were beginning to
wonder if mosquitoes could spread malaria. Ross collected mosquitoes and painstakingly dissected them under a microscope. He
discovered the micro-organism that was known to cause malaria, inside the bodies of Anopheles mosquitoes. This led to the realisation
that insects could carry pathogens, that is, they can be vectors of disease.

          Use reference books or the Internet to gather information to trace how scientists identified the cause and prevention of
           malaria.
          Process this information to show how their work contributed to our understanding of the cause and prevention of malaria.
           Trends and patterns could be well illustrated through the use of an annotated timeline. The table below is a guideline.

Date          Development
              The disease malaria was described by the Romans. Malaria was thought to come from swamps so the name means
18 BC
              'bad air'
1820          Quinine used to prevent the disease
1880          Charles Laveran a French army doctor observed the malarial parasite
1886          Golgi observed asexual reproduction in the protozoan Plasmodium and identified two species
1898          Giovanni Grassi named the Anopheles mosquito as the carrier of the malarial parasite
1897          Ronald Ross discovered that Plasmodium was the protozoan that caused the disease malaria.
1940          Chloroquinine the first synthetic anti-malarial drug was used
Distinguish between:

    o      prions
    o      viruses
    o      bacteria
    o      protozoans
    o      fungi
    o      macro-parasites

and name one example of a disease caused by each type of pathogen

   Pathogen                               Description                                          Examples of diseases it causes
Prions             Protein that has been altered from its normal structure            scrapie in sheep
                   and can then alter other proteins to develop more prions,          spongiform encephelopathy in cattle (mad cow disease)
                   so that the change spreads like a chain reaction.                  Creutzfeldt-Jakob (CJD) disease in humans

Viruses            Consist of DNA or RNA enclosed in protein, live inside living      influenza
                   cells. They are so small that they cannot be seen with a           measles
                   light microscope.                                                  a common cold
                                                                                      herpes
                                                                                      AIDS
                                                                                      Warts
                                                                                      Hepatitis
                                                                                      Foot-and-mouth disease
                                                                                      Plum pox virus

Bacteria           Very simple cells with no internal membranes.                      Boils
                                                                                      Cholera
                                                                                      Legionnaire's disease
                                                                                      Tuberculosis
                                                                                      Crown gall blight

Protozoans         Microscopic single-celled organisms with internal                  Amoebic dysentery
                   membranes.                                                         Giardia,
                                                                                      Malaria,

Fungi              Heterotrophic organisms. Some (e.g. yeasts) are                    Ringworm
                   unicellular, others consist of long branching threads.             Tinea
                                                                                      Thrush
                                                                                      Many plant diseases such as damping off in seedlings

Macro-organisms Organisms that are visible to the naked eye, also called              fleas
                parasites.                                                            ticks
                                                                                      tapeworms
                                                                                      bilharzia worms
                                                                                      hydatid worms
                                                                                      liver fluke
                                                                                      many plant parasites, e.g. aphids
Identify the role of antibiotics in the management of infectious disease

        Antibiotics play an important role in the management of infectious diseases. Antibiotics were discovered by Alexander Fleming in
         1928. They are naturally occurring compounds produced by one organism to prevent the growth of bacteria. Before the
         discovery of antibiotics, many people died of what we now would think of as simple infections.

Process information from secondary sources to discuss problems relating to antibiotic resistance

Background

Unfortunately, the overuse of antibiotics has led to the selection of more virulent bacteria that are resistant to antibiotics.

When antibiotics were first introduced, they had a dramatic effect on the pathogens that cause disease. Over time, it became apparent
that the effects of the antibiotics were beginning to become less potent. This was because of the development of drug resistance in the
pathogen. Each time an antibiotic is used, there may be some individual pathogens that have a natural resistance to the drug. These
naturally resistant individuals are left to breed the next generation and pass on the genetic information that made them resistant. The
next time the drug is used, it will have no effect. Overuse of antibiotics has resulted in "superbugs". These strains are resistant to
antibiotics and include vancomycin resistant golden staph (Staphylococcus aureus). These organisms are not destroyed by our strongest
antibiotics. Scientists are developing new antibiotics such as Zyvox to deal with multi-resistant bacteria. In the future, unless new
antibiotics are produced, common infections will once again be responsible for many deaths.

Many household products and cleaning agents now contain antibiotics. These do not kill all bacteria so act as a selecting agent for
antibiotic resistant bacteria. These can increase in number without competing with other bacteria.

The use of antibiotics in farm animals also has the same effect of selecting for antibiotic resistant bacteria. Some farm industries put
human antibiotics into the feed of their animals, thus increasing the build up of antibiotic resistant bacteria. During the production of
meat, animals are given antibiotics to prevent infections. When the meat reaches the table, it may still contain these animal antibiotics.
This could lead to more antibiotic resistant bacteria.

It is important to complete a course of antibiotics even when the symptoms are gone. This will ensure that the bacteria have been
completely destroyed. Not finishing antibiotics can lead to the selection of antibiotic resistant strains.

        Process this information to discuss the problems of antibiotic resistance. Trends and patterns could be illustrated by the
         unending cycle between the introduction of new antibiotics and the development of resistance in bacteria.
Identify data sources, gather, process and analyse information from secondary sources to describe one named infectious
disease in terms of its:

    o       cause
    o       transmission
    o       host response
    o       major symptoms
    o       treatment
    o       prevention
    o       control

           To address this dot point, it is a good idea to select an infectious disease that interests you or that represents a significant
            problem in your community.

            Use the list presented in the dot point to determine the type of information that you need to collect. Gather the information
            from a range of sources including digital technologies, locally available health brochures or pamphlets and the Internet. Process
            the accuracy of the information by looking for information that is consistently represented across a range of reputable
            publications. Analyse your information by developing accurate generalisations into short notes.

A good example of a named infectious disease is malaria. The following is a description of the disease.

Factors                     Description
Cause                       The parasitic protozoan, Plasmodium

Transmission                Anopheles mosquito is the insect vector. Blood from a malaria victim contains Plasmodium sex cells. These form zygotes
                            in cysts in the stomach wall of the mosquito and mature into sporozoites. When a cyst bursts, the sporozoites travel to
                            the mosquito salivary glands, from where they are transferred to the victim of the mosquito bite. The sporozoites travel
                            to the liver, multiply and then enter the red blood cells, where they also multiply. When the infected cells burst, they
                            cause the malarial fever. Male and female gametes are produced from these sporozoites, which are then taken in the
                            blood the next time a mosquito bites.

Host response               When in the blood cells the host produces antibodies against Plasmodium

Major symptoms              Chills, fever, sweating, delirium and headache

Treatment                   Anti-malarial drugs such as quinine and chloroquinine

Prevention                  Cover up after dark and use personal insecticide, mosquito nets

Control                     Draining swamps, spraying with insecticides.
4. Defence against disease

4. Often we recognise an infection by the symptoms it causes. The immune response is not so obvious, until we recover

Background: Our bodies have three types of defence against pathogens. The first consists of several barriers that prevent the entry of
micro-organisms. The second is the action of white blood cells in destroying foreign particles, in a process called phagocytosis. The third
is carried out by the immune system, which plays a complex role in targeting and destroying pathogens as well as helping to make our
bodies resistant to them.

Our bodies contain very large numbers of bacteria (15% of your body weight) and many of those in the intestine are essential for our
wellbeing. The collective term for all the micro-organisms in our bodies, both the beneficial and harmless ones, is microflora. An
imbalance of microflora in the gut can lead to disease symptoms such as diarrhoea and malabsorption of nutrients.


Gather, process and present information from secondary sources to show how a named disease results from an imbalance of
microflora in humans.

Background: Pathogenic microflora usually attack specific parts of the body. For example, the protozoan that causes malaria lives in red
blood cells, the bacterium that causes cholera lives in the intestine, the bacterium that causes trachoma lives in the eyes, one type of the
Herpes virus is active in cells around the lips and nose (causing cold sores) and another type is active in cells in the genital area (genital
herpes).

          Choose a disease that results from an imbalance of microflora in humans, such as Crohn's disease or candida (thrush). Use
           biology textbooks, library references and, if possible, the Internet to gather information about the cause, symptoms and effects
           of the disease.
          To process the sources you find, assess their reliability by comparing the information provided. Look for consistency of
           information.
          It is appropriate for this syllabus point that you present your findings as a report. A scaffold and some language features of a
           report follow:


               Scaffold for a report                                                          Features

Classification                                       Classify the disease. Briefly preview the features to be described. Use generalised terms.
                                                     Use linking verbs like is, has, becomes. Use present tense.

Description                                                   Focus on a specific feature for each paragraph. Begin each paragraph with a topic
                                                               sentence.
(Feature 1: e.g. cause)
                                                              Use present tense.
(Feature 2: e.g. symptoms)
                                                              Use action verbs, such as occurs, called, makes.
(Feature 3: e.g. effects)
Identify defence barriers to prevent entry of pathogens in humans:

        o     skin
        o     mucous membrane
        o     cilia
        o     chemical barriers
        o     other body secretions

            Line of defence                             Description                                              What it does


skin                              Skin continuously grows by new cells being produced        When unbroken, skin prevents the entry of pathogens.
                                  from below. Cells fit tightly together to form a           Pores in the skin secrete substances that kill bacteria.
                                  protective layer covered by dead cells.


mucous membrane                   cells lining the respiratory tract and openings of the     Mucus is sticky and traps pathogens and other
                                  urinary and reproductive systems that secrete a            particles. When there are many pathogens more
                                  protective layer of mucus                                  mucus is produced to flush them out.


cilia                             Hair-like projections from cells lining the air passages   Move with a wavelike motion to push pathogens from
                                                                                             the lungs up to the throat.


chemical barriers                 acid in the stomach; alkali in the small intestine; the    Stomach acid destroys pathogens, including those that
                                  enzyme, lysozyme, in tears                                 are carried to the throat by cilia and then swallowed.
                                                                                             Alkali destroys acid resistant pathogens. Lysozyme
                                                                                             dissolves the cell membranes of bacteria.


Other body secretions             secretions from sweat glands and oily secretions from      Contain chemicals that destroy bacteria and fungi.
                                  glands in hair follicles
Identify defence adaptations, including:

    o    inflammation response
    o    phagocytosis
    o    lymph system
    o    cell death to seal off pathogen

inflammation response

        Inflammation occurs when blood vessels around an infected area are supplied with extra blood. This makes the area swollen and
         red. The release of histamines by the damaged tissue increases the permeability of the blood vessels, which allows white blood
         cells to leave the blood vessels and move into the damaged tissue.

phagocytosis

        Some white blood cells, called macrophages and neutrophils, can very easily change their shape so that they flow around
         particles and completely enclose them within their cell, where they are broken up by cell enzymes. This is called phagocytosis.


lymph system

        The lymph system returns intercellular fluid to the blood system, filters cell debris and produces white blood cells responsible
         for the immune response.


cell death to seal off pathogen

        For some pathogens, macrophages and lymphocytes completely surround a pathogen so that it is enclosed in a cyst. The white
         cells involved die, so that the pathogen is isolated from its food supply and also dies.

Identify antigens as molecules that trigger the immune response.

Background: If the previous two systems fail to destroy a pathogen then the immune system comes into operation. It depends on
distinguishing between parts of the body and particles from outside. It is important that phagocytes are able to make this distinction,
otherwise they would destroy body cells.

        Any molecule that the body recognises as being foreign is called an antigen. Antigens activate the immune response.

Explain why organ transplants should trigger an immune response.

        Organs from another organism are recognised as foreign by the human immune system. The surfaces of the new organ contain
         antigens. These trigger an immune response and body attacks the new organ as if it were a pathogen.
5. The immune response

5. MacFarlane Burnet's work in the middle of the twentieth century contributed to a better understanding of the immune
response and the effectiveness of immunisation programs


Background: Sir Frank Macfarlane Burnet was an Australian scientist who won the Nobel Prize for his research into physiology. He
studied immunology and worked on the development of the influenza vaccine.

Identify components of the immune response

         o   antibodies
         o   T cells
         o   B cells

         Name                                  What it is                                                   What it does
antibodies            proteins that the body produces when it detects antigens.     join with antigens so that they are clumped together and can
                      Each different antigen stimulates the production of its own   be more easily recognised and destroyed by macrophages
                      particular antibody.


B cell                a special kind of lymphocyte produced in the bone marrow      When a B cell recognises an antigen, it divides repeatedly to
                      (thus B cell)                                                 produce a mass of identical cells (clones) that work as
                                                                                    antibody producers (plasma cells).


T cell                another kind of lymphocyte, that is passed through the        Some produce toxic substances that destroy cells that have
                      thymus gland (thus T cell)                                    been invaded by a virus. Others help the B cells to divide
                                                                                    rapidly.



Describe and explain the immune response in the human body in terms of:

         o   interaction between B and T lymphocytes
         o   the mechanisms that allow interaction between B and T lymphocytes
         o   the range of T lymphocytes types and the difference in their roles

Interaction between B and T lymphocytes

B and T lymphocytes interact as they are both attacking the same antigen. Helper T cells (see below) stimulate B cells and T cells to clone.

The mechanisms that allow interaction between B and T lymphocytes

The T lymphocytes that help B lymphocytes are called helper T cells (Th cells). If a B cell has an antigen on its surface, there is a risk that a
T cell will recognise the antigen and attack it together with the B cell. This does not happen because T cells are able to recognise “self”
molecules that are on the surface of B cells. Every person has their own particular "self" molecules, so there are millions of different B
cells. They are like personal identity used to identify cells to T lymphocytes. This means that, in the case of organ transplants, T cells can
recognise cells that have come from a different body and so help B cells to destroy them. Only identical twins have the same “self”
molecules on their B cells.

The range of T lymphocytes types and the difference in their roles
           Type of T cell                                                                Roles
killer T cells (Tc cells)            attack and destroy macrophages that have engulfed an antigen. They produce cytotoxins.


helper T cells (Th cells)            secrete chemicals that stimulate cloning in B and T cells


memory T cells                       remain in the body and reactivate quickly with subsequent infections by the same antigen


suppressor T cells                   stop the reaction when the antigen is destroyed



Outline the reasons for the suppression of the immune response in organ transplant patients

           When an organ is transplanted it is recognised by the immune system in the body as non-self. The body attacks the new organ as
            if it is an invading pathogen. To overcome this problem, transplant patients are given powerful drugs to suppress their natural
            defences. This can lead to complications, as the patient has reduced defences against any pathogen that they may encounter.

Process, analyse and present information from secondary sources to evaluate the effectiveness of vaccination programs in
preventing the spread and occurrence of once common diseases, including small pox, diphtheria and polio

Background: Vaccination gives artificially acquired immunity from a disease. Once common diseases, such as small pox, diphtheria and
polio, are now uncommon because of successful vaccination programs. Smallpox was the first disease for which a vaccine was developed.
Edward Jenner did this in 1796. The vaccination program that was started in the 1960s was so successful that the World Health
Organisation (WHO) has declared it eradicated. Diphtheria vaccine is given as part of a triple antigen injection that protects against
diphtheria, tetanus and whooping cough. In 1990, WHO stated that 80% of children had been vaccinated against this disease. There
continues to be outbreaks of this disease and continued vaccination is recommended. It is no longer thought of as a major child killer.
Polio caused thousands of children to become paralysed every year. A vaccine was introduced in 1955. It became available as an oral
vaccine in the 1960s. Worldwide, the number of cases is down by 80%.

           Use the Internet, biology text books and encyclopedias to gather information on the use of vaccines over the last 200 years and
            on the use of vaccines in controlling common diseases. Make sure you gather information on small pox, diphtheria and polio.
            Numerical data or graphs are particularly useful for the evaluation purposes.
           Assess the reliability of secondary information and data by considering information from various sources. This is an ideal
            opportunity to process claims about the effectiveness of vaccination made in the mass media.
           Analyse information by identifying trends or contradictions.
           Present your findings as an evaluation report. Consider such aspects as how vaccination programs are implemented in
            Australia and different parts of the world. Discuss the problems associated with producing and using vaccines, especially in less
            developed countries. Comment on the effectiveness of vaccination. Consider using graphs to demonstrate the points you make.

Outline the way in which vaccinations prevent infection

Background: When a person has had an infection, some of the B cells produced in response to the pathogen are stored in the lymphatic
tissue. They are called memory B cells. They are ready to provide a very rapid response if the same pathogen later attacks the body.

           Vaccination is a way of giving a person the “experience” of having had an infection without actually having it, so that the body
            responds to the “experience” by producing the appropriate memory B cells.
           The way in which the “experience” is given depends on the pathogen. In the case of small pox a very similar, but very much less
            harmful pathogen (cow pox), was used. In other cases, the virus is made weaker, and therefore harmless (attenuated), before
            being used in a vaccine. Examples of this type of vaccine are those for poliomyelitis, measles and whooping cough.
   Many pathogenic bacteria are harmful to the body because of the toxins they produce. For diphtheria these toxins are modified
    to produce the vaccine.
   Whatever the source of the vaccine, the effect is the same. It introduces antigens into the body so that B cells are activated to
    produce large amounts of antibody and B cells that are stored in the lymph system are ready for a future attack by the
    particular pathogen.
6. Epidemiological Studies

6. Epidemiological studies involve the collection and careful statistical analysis of large quantities of data. Such studies assist
the causal identification of non-infectious diseases

Background: An epidemic is an outbreak of a disease that affects a large number of people in a particular place at the same time.
Epidemiology is the study of epidemics, especially by looking for common factors in populations affected by the disease. It is based on
careful collection and analysis of statistical information.

Gather, process and analyse information to identify the cause and effect relationship of smoking and lung cancer

Background: Cause and effect is difficult to establish. For example, it is one thing to say that everyone with a certain disease also
watches television, but to make the next step, and say that television caused the disease, is not possible. There could be any number of
other possible causes for the disease. This difficulty arises with epidemiological studies. Smoking and lung cancer have been linked by
research time after time but it is difficult to get the manufacturers of tobacco products to accept that it is a direct cause and effect
relationship, that is, smoking causes lung cancer.

        Use the Internet to gather information on lung cancer. Make sure the information provides examples of or discusses the results
         of epidemiological studies.
         Process the information to identify statistics that can be used to demonstrate a possible link between cause and effect for the
         disease chosen.
        Analyse the information to decide how the cause and effect relationships demonstrated in epidemiological studies can be used
         to identify the cause of the disease.

Identify and describe the main features of epidemiology using lung cancer as an example

        Epidemiological studies need to investigate cause and effects of a disease. To be valid they must:
              o focus on large groups of people rather than individuals and relate to a target population that can be identified. This
                  allows statistics to be used to identify trends and possible causative factors.
              o use populations where there is occurrence of the disease and where there are unequal exposures to the suspected or
                  possible causes. No conclusions about the effect of smoking could be drawn from a group of people who each smoke 20
                  cigarettes a day
              o allow for analysis of factors that might contribute to the occurrence of the disease among those afflicted, such as age,
                  sex, ethnic group, and occupation.
Identify causes of non-infectious disease using an example from each of the following categories:

    o    inherited diseases
    o    nutritional deficiencies
    o    environmental diseases

Inherited diseases

        Inherited diseases result from mutations that lead to the production of different or faulty enzymes, resulting in impaired body
         function.

         Examples

         Examples of inherited diseases are Down syndrome, colour blindness, haemophilia, phenylketonuria, thalassaemia and sickle cell
         anaemia.

        Down syndrome is an inherited disease that is caused by the non-disjunction of chromosome 21. This results in three
         chromosomes and not the usual two (trisomy 21). People with Down syndrome have a characteristic appearance and may have a
         shortened life span. Mothers who have children later in life are more prone to produce Down syndrome children.

Nutritional deficiencies

        The effect of nutritional deficiencies depends on the kind of deficiency. In some parts of the world diets may be deficient in
         certain elements, such as iodine, copper, iron or zinc.

         Examples

         Examples of nutritional diseases are scurvy, rickets, goitre, kwashiorkor and beri beri.

        Scurvy is caused by a deficiency in vitamin C. Symptoms include bleeding gums and tooth loss. It is treated by increasing the
         intake of food and drinks containing vitamin C, such as citrus fruit.
        Rickets is a metabolic bone disease resulting from a deficiency of Vitamin D. This can be due to a lack of sufficient vitamin D in
         the diet or due to insufficient exposure to sunlight. The disease is called osteomalacia when it occurs in adults.

Environmental diseases

        Environmentally caused diseases include those due to lifestyle, such as smoking-related diseases, as well as those caused by
         something in the environment, such as lead or substances that cause allergies.


         Examples

         Examples of environmental diseases include smoking-related diseases, Minamata disease, lead or asbestos related diseases and
         melanoma.

        Mesothelioma is caused by exposure to asbestos and patients don't get any symptoms until 20 to 30 years after exposure. There
         is no cure and treatment can only slow down the progression of the disease.

Identify data sources, plan and perform a first hand investigation or gather information from secondary sources to analyse and
present information about the occurrence, symptoms, cause, treatment/management of a named non-infectious disease
If you know someone with a non-infectious diseases, you could ask their permission to interview them and then carry out a first-hand
investigation of the disease.

        If this is the case, begin by determining the type of data that needs to be collected through interview and what information you
         may need to collect from secondary sources. Consider how you might analyse the information to make it useful in generalising
         about the occurrence, symptoms, cause and treatment or management of the disease.
        Plan your investigation so that valid and reliable information is collected. You may need to research some issues from
         secondary sources, particularly if your subject is uncertain about particular aspects required.
        Perform your investigation by conducting the interviews and compiling a report. You could summarise your findings in a table
         format, like the one below.

If you complete this syllabus point using secondary sources, you could:

        choose a non-infectious disease from one of the categories listed in the previous section.
        gather information from a range of resources, including popular scientific journals, digital technologies like CD-ROMs and the
         Internet.
        analyse the information to make a generalisation for each of the factors being examined.
        present a summary using a table like the one below.

         Name of disease

         Occurrence




         Symptoms




         Cause
Treatment or management
7. Modern strategies

7. Increased understanding has led to the development of a wide range of strategies to prevent and control disease

Background: Modern knowledge of disease has led to the development of a wide range of strategies to prevent and control disease.

Discuss the role of quarantine in preventing the spread of disease and plants and animals into Australia and across regions of
Australia.

        Australia has generally been fortunate in preventing the spread of plant and animal disease from other parts of the world
         because of its geographical isolation. Quarantine seeks to prevent the entry of harmful diseases into Australia and to stop the
         spread of diseases within Australia.
        These diseases cause huge financial losses to farmers in other countries. Australia is able to sell its products to overseas
         markets because of the absence of diseases, like mad cow disease and foot-and-mouth.
        Australia also has declared fruit-fly free areas where the produce is sold with a guarantee of no fruit fly. This can be done by
         having inspections and bins to put fruit in when entering particular fruit growing areas.

Perform an investigation to examine plant shoots and leaves and gathering first hand information of evidence of pathogens and
insect pests

        To perform this investigation, you may need some background information to aid identification of the pathogens. Use gardening
         books or the Internet to gather pictures of plant diseases.
        When you know what several plant diseases look like, go to an area of vegetation (such as a garden, park or area of bush) and
         examine plant shoots and leaves to gather evidence of plant diseases caused by pathogens or insect pest attack. You should aim
         to identify at least two examples of pathogens and insect pests if possible. Look for black patches on the leaves, white powdery
         residue or other spots that indicate a pathogen such as a fungus, or holes in the leaves caused by insect pests such as
         caterpillars. Use a hand lens to observe the symptoms.
        For each example, record observations systematically and use the evidence to suggest what kind of organism has caused the
         disease.

Explain how one of the following strategies has controlled and/or prevented disease:

    o    public health programs
    o    pesticides
    o    genetic engineering to produce disease resistant plants and animals

Public health programs

        These provide quarantine, sanitation, safe drinking water and immunisation. They are also responsible for advertising campaigns
         that target cancer and AIDS. Examples of successful health campaigns are the Slip! Slop! Slap! skin cancer advertisements, the
         advertisements that show various diseases that can be caused by smoking and the Grim Reaper series for education about AIDS.

Pesticides

        Pesticides, such as DDT, have been used to destroy mosquitoes, which are the vectors of some diseases, such as malaria and
         dengue fever.

         A good example of a strategy to control or prevent disease is the pesticide control of the disease malaria. Adult mosquitoes can
         be destroyed by chemicals such as DDT, dieldrin, or by safer chemicals, such as pyrethrums. In 1956, the World Health
         Organisation was responsible for a major campaign using a residual form of DDT. DDT has been banned in many countries of the
         world because of its harmful ecological effects, but it is still used for mosquito eradication in malarial areas. This has rid many
         areas of the world from malaria but has unfortunately not reduced it globally and malaria is still a major killer of children today.
         Many areas have DDT-resistant mosquitos. Other pesticides, such as organophosphates and pyrethrums, have become popular.
         In some areas, bed nets have been sprayed with pyrethrums and have been found to be effective in controlling mosquitoes.

Genetic engineering to produce disease resistant plants and animals

        Genetically engineered plants can now kill their own pests because of the insertion of a gene from a soil bacterium, Bacillus
         thuringiensis (Bt). Bt cotton was the first genetically engineered crop grown in Australia. The bacteria contain a gene that
         produces chemicals that kill certain insects. By taking that gene from the bacteria and inserting into the genome of plants, the
         plants now produce the chemical that will kill insect pests.

Gather, process information and use available evidence, to discuss the changing methods of dealing with plant and animal
diseases, including the shift in emphasis from treatment and control to management or prevention of disease

Background: There has been a shift from waiting for a disease to occur, to preventing the occurrence of the disease. This can be seen in
agriculture where genetically resistant crops are grown so that the plants do not have to be sprayed for diseases later in life. Animal and
plant diseases have been managed by quarantine restrictions in Australia. Diseases, such as foot and mouth, rabies and plum pox, are
managed by not allowing infected organisms to enter the country. World-wide immunisation has caused diseases such as small pox to be
eradicated.

        Consider all the aspects of the disease you have studied. Make notes on those aspects that relate to the above syllabus
         statement.
        Using these notes, plan a discussion of the changing methods of dealing with plant and animal diseases.
        Decide whether you need further information, and if so, gather it from textbooks or the Internet.
        Write a short concise response from the available evidence to show what you deduce about the shift in emphasis from
         treatment and control to management or prevention of disease. Make sure the response has:
              o an introductory paragraph, written in general terms
              o a series of paragraphs that focus on specific issues. Each paragraph could discuss any debatable issues, e.g.
                  advantages and disadvantages of a particular approach
              o a concluding statement, providing your position or recommendations based on your evaluation.




Process and analyse information from secondary sources to evaluate the effectiveness of quarantine in preventing the spread
of plant and animal disease into Australia or across regions of Australia

        Use the Internet to obtain and process information from a range of sources, including the Australian Quarantine and Inspection
         Service (AQIS) about the control of the movement of plants and animals and their products into Australia and within Australia.
         Quarantine prevents entry of goods that may carry diseases or pests at airports and seaports. Affected goods are destroyed.
         Fumigation is also part of the quarantine program.
        Analyse this information to evaluate the effectiveness of quarantine regulations in Australia, being sure to identify relationships
         as well as contradictions in the information.

				
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