Topic 11: Human health and physiology
11.1 Defence against infectious disease
Assessment statement
Example Questions
11.1.1
Describe the process of blood clotting.
Which is the correct sequence of events when skin is cut and bleeding
occurs?
I.
Thrombin is produced
II.
Fibrinogen is converted into fibrin
III.
Platelets release clotting factors
A.
I  II  III
B.
I  III  II
C.
III  II  I
D.
III  I  II
11.1.2
Outline the principle of challenge and
response, clonal selection and memory cells
as the basis of immunity.
11.1.3
Define active and passive immunity.
Define the terms active, passive, natural and artificial immunity. (4)
active immunity – production of antibodies by the organism itself;
passive immunity – acquisition of antibodies from another organism / from
elsewhere;
natural immunity – immunity due to infection / acquisition from mother;
artificial immunity – due to inoculation with vaccine / antibodies /
vaccination;
11.1.4
Explain antibody production.
Explain the production of antibodies. (8)
antigens stimulate an immune response;
antibodies are produced in response to specific antigens;
antibodies are made by B-cells / lymphocytes / plasma cells;
antigen is engulfed by macrophages;
antigen is presented on macrophage membrane;
helper T-cells bind to antigen (on macrophage);
helper T-cells are activated;
helper T-cells activate B-cells;
B-cells clone;
into plasma cells and memory cells;
plasma cells produce specific antibodies to the antigen;
memory cells for long-term immunity;
a faster / stronger response later;
11.1.5
Describe the production of monoclonal
antibodies and their use in diagnosis and in
treatment.
State one use of monoclonal antibodies in diagnosis and one use in
treatment. (2)
Award [1 max] for use in diagnosis and [1 max] for use in treatment.
diagnosis:
detection of (antibodies to) HIV;
detection of HCG / pregnancy test kits;
detection of cardiac enzyme in suspected heart attacks;
detection of tissue / blood type;
testing for (different strains of) malaria;
ELISA test;
treatment:
targeting cancer cells with attached drugs;
treatment of rabies / Ebola / lymphoma
destroying T-cells to reduce rejection of transplants;
11.1.6
Explain the principle of vaccination.
Outline the process of immunization. (6)
vaccine is used (to induce immunity artificially);
vaccine contains dead / weakened /
attenuated forms of the pathogen / bacterium / virus;
vaccine is injected / ingested;
booster shot may be needed;
immunity due to vaccination /
immunisation lasts for life / a long period;
immunity to a disease is due to presence of the
appropriate antibodies / cells that can make them;
active immunity is when the body makes the antibodies itself;
natural immunity is caused by exposure to a disease /
pathogen / bacterium / virus;
antibodies are made in response to antigens / vaccine;
memory cells are made in response to antigens / vaccine;
11.1.7
Discuss the benefits and dangers of
vaccination.
Discuss the benefits and dangers of immunization against bacterial and viral
infections. (8)
benefits:
prevent disease;
prevent epidemics;
healthier society;
reduce medical costs;
less job absenteeism;
disease free cattle / more food;
eradicate diseases / smallpox entirely;
prevent harm / disabilities due to diseases;
speed up the body’s response to a disease;
allergic reactions;
autoimmune response;
weakened virus becomes virulent / get disease;
danger of side-effects / example of side-effects;
vaccine with side-effects eg salk vaccine /
whooping cough vaccine / MMR vaccine;