Download 7.5 Immune response – questions and answers Q1. Bk Ch7 S7.6 Q1

7.5 Immune response – questions and answers
Q1.
Bk Ch7 S7.6 Q1
Briefly summarise what happens in the body during an immune response.
A1.
Bk Ch7 S7.6 A1
The body mounts an immune response when a pathogen has gained entry to the body. During an
immune response white blood cells called lymphocytes are produced. There are two main kinds of
lymphocytes: B cells and T cells. The B cells produce plasma cells that in turn produce antibodies
against the foreign antigens on the pathogen. These antibodies bind with the foreign antigens, forming
an antigen–antibody complex. This inactivates the pathogen. T cells bind to the foreign antigen and
attract phagocytes that engulf and destroy the invading cells.
Q2.
Bk Ch7 S7.6 Q2
Explain what is meant by the term ‘cell-mediated immune response’.
Explain what is meant by the term ‘humoral (blood) response’.
a
b
A2.
Bk Ch7 S7.6 A2
a
b
A ‘cell-mediated immune response’ is the response of T cells to the presence of foreign antigens
on cells not recognised as ‘self’. In cell mediated immune responses the T cells destroy the
invading cells.
During the ‘humoral’ response B cells present in the blood and lymph are activated by the
presence of antigens. Activated B cells clone themselves and then differentiate, either into
plasma cells that send antibodies into the blood or into memory cells.
Q3.
Bk Ch7 S7.6 Q3
Define memory cells. Describe their role in defending the body against disease.
A3.
Bk Ch7 S7.6 A3
B cells and T cells form memory cells. These cells retain a ‘memory’ of a previously encountered
antigen so that the next time the body is exposed to the same antigen (pathogen) a more rapid response
occurs and the pathogen is destroyed before any symptoms can be produced.
Q4.
Bk Ch7 S7.6 Q4
Complete the following table, summarising the role of the different components involved in the
immune response.
Immune system
component
Kind of structure
Produced in/by
Role
T cell
B cell
Antigen
Antibody
A4.
Bk Ch7 S7.6 A4
Immune system
component
Kind of structure
Produced in/by
7.5 Immune response QA
Copyright
© Pearson Australia (a division of Pearson Australia Group Pty Ltd)
Role
page 1 of 3
T cell
Lymphocyte
Produced in the bone
marrow and matures in
the thymus gland
Cytotoxic T cells destroy
cells that have foreign
antigens; helper T cells
assist in the regulation of
T cell and B cell function
B cell
Lymphocyte
Bone marrow
Multiply and differentiate
into plasma cells that
produce antibodies and
memory B cells that
recognise the foreign
antigen the next time it is
encountered so that a
more rapid response can
be elicited
Antigen
Protein
Present on cells of living
organisms
Stimulate the production
of antibodies
Antibody
Immunoglobulin
(protein)
Produced by B cells in
response to the presence
of a foreign antigen
Bind with foreign antigen
thereby inactivating
invading pathogen
Q5.
Bk Ch7 S7.6 Q5
a
b
Define ‘immunisation’.
Draw a flow chart illustrating how the body’s immune system responds to a poliomyelitis
vaccination.
A5.
Bk Ch7 S7.6 A5
a
b
Immunisation involves the injection of a vaccine that is intended to produce resistance to an
infection caused by a particular pathogen.
1. The poliomyelitis vaccine is given in oral form.
2. An attenuated strain of poliomyelitis stimulates the body to mount an immune response.
3. Antibodies that are specific to poliomyelitis antigens are produced.
4. Protection against polio is conferred.
Q6.
Bk Ch7 S7.6 Q6
a
b
Explain the difference between active and passive immunity.
Use an example to outline at least one advantage and one disadvantage of these two processes.
A6.
Bk Ch7 S7.6 A6
a
b
Active immunity involves the body producing antibodies in response to the presence of a foreign
antigen. Passive immunity occurs when antibodies specific to a particular pathogen are injected
into a person rather than the person producing the antibodies.
Active immunity is long lasting because the body has produced the antibodies itself and therefore
retains a ‘memory’ of the pathogen. However, when a person is immunised against a particular
pathogen, for example the measles virus, they can display some mild symptoms of the infection.
Passive immunity does not confer immunity as long lasting as active immunity; however, it does
confer immunity for people who would otherwise be at risk because they cannot produce their
own antibodies or because to stimulate antibody production may be risky. This would be so in the
case of a pregnant woman who has had exposure to the rubella virus.
Q7.
Bk Ch7 S7.6 Q7
a
b
Describe the circumstances in which the activity of the immune system is deliberately suppressed.
Explain the reason for this.
7.5 Immune response QA
Copyright
© Pearson Australia (a division of Pearson Australia Group Pty Ltd)
page 2 of 3
c
Outline any disadvantages associated with this practice?
A7.
Bk Ch7 S7.6 A7
a
b
c
Transplant patients undergo treatment to suppress the activity of the immune system.
When a patient receives a transplanted organ their body will recognise the cells of the new organ
as foreign and mount an immune response against them, that is, antibodies will be produced to
destroy the foreign cells. In order to ensure that this response is reduced to a minimum the
immune system must be suppressed.
When the immune system is suppressed in transplant patients they become more susceptible to
infections because their immune system is less likely to mount a vigorous attack against the
pathogen.
Q8.
Bk Ch7 S7.5 FQ8
Explain the difference between an antigen and an antibody. Use diagrams to illustrate the specificity of
the antigen–antibody complex.
A8.
Bk Ch7 S7.5 FA8
An antigen is a protein whose presence stimulates the production of antibodies in the host organism.
Antibodies are substances produced in response to the presence of foreign antigens. The role of
antibodies is to lock onto a foreign antigen to disarm or destroy it.
7.5 Immune response QA
Copyright
© Pearson Australia (a division of Pearson Australia Group Pty Ltd)
page 3 of 3