Explain how the structure of an antigen-binding site makes it specific to a particular antigen, as shown in Fig. 6.1.
State the function of the hinge region of the antibody shown in Fig. 6.1.
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Antibodies can bind to membrane receptors on cells of the immune system, such as macrophages.
Suggest an advantage of antibodies binding to receptors on macrophages.
It is estimated that the immune system of each person can make enough antibodies to bind to over different antigens.
When plasma cells make antibody molecules they combine the polypeptides produced by the expression of genes for heavy chains and the genes for light chains.
Research has shown that producing this very large number of antibodies is only possible by modifying the primary transcripts of the genes that code for heavy chains and the genes that code for light chains.
Suggest how this modification of the primary transcripts occurs in plasma cells.
U4 and V4 are types of active T-lymphocyte. State the names given to these types of T-lymphocyte.
U4 ______
V4 ______
Polio is a highly infectious viral disease. The virus infects the nervous system of humans. The disease can cause total paralysis within hours and can be fatal.
The Global Polio Eradication Initiative (GPEI) was started in 1988 by the World Health Organization. In 2022, polio had been successfully eradicated from most of the world. However, cases of the disease have been recorded in some countries.
Discuss the steps that must be taken by health authorities during a vaccination programme if an infectious disease, such as polio, is to be eradicated from the whole world.
The toxins released by some pathogenic bacteria can be altered chemically so that they are harmless. These harmless toxins are called toxoids.
Toxoids are used in vaccines to provide protection against some infectious diseases.
Describe the response of the immune system to the injection of a toxoid.
Use Fig. 3.1 to explain how the structure of the variable region of an antibody molecule is related to its function.
RA is classed as an auto-immune disease where the immune system treats some self antigens as non-self.
Explain what is meant by the term non-self antigens.
Name the parts of the antibody molecule labelled P, Q and R.
P ______
Q ______
R ______
Name the type of bonds that hold the polypeptide chains together in the antibody structure.
Suggest how the binding of monoclonal antibody to the diseased cells causes their destruction by cells of the person’s immune system.
Explain why the parasites were killed using radioactivity and not by using high temperatures.
With reference to Fig. 5.1, explain why the researchers decided to use the form of the parasite which is injected by mosquitoes and not the form which leaves the liver.
The volunteers who were injected with the killed parasites produced antibodies, which provided some protection against the disease.
Outline the events that occur following injection of the parasites, which lead to the production of antibodies.
Explain why the vaccine for measles is not given in the first few months of a child’s life.
The World Health Organization (WHO) publishes data on the vaccination programmes for infectious diseases. The WHO recommends vaccination rates of over 90% of children.
Each health authority in a country reports its success in vaccinating children in their district. The WHO uses these figures to estimate the percentage of districts in each country that vaccinate 90% of children against measles.
The WHO also collects statistics on death rates of children under the age of 5 from all causes, including infectious diseases.
Fig. 6.1 shows these statistics for 24 countries for the year 2007.
Use the information in Fig. 6.1 to explain why the WHO recommends immunisation of 90% of children.
Explain the roles of the cells, A, B and C in an immune response.
In your answer use the terms antigen and non-self.
Choose the correct term from the list below to complete Fig. 4.1.
lymphocytes antigens mitosis vaccine
-lymphocytes plasma cells macrophages
Explain why the person is unlikely to become ill if they are infected by the same pathogen some months later.
Some parents decide that their children should not take part in a vaccination schedule.
Suggest how a country-wide vaccination schedule can give protection against infection to unvaccinated children.