Download Immunity Answers

Immunity Questions
1
Describe three barriers which prevent pathogens from entering the body.
2
Draw labelled diagrams of a macrophage and a neutrophil to the same scale.
3
Describe phagocytosis by a neutrophil using the words: histamine, antibody, engulf and lysosome.
4
Copy and complete the following table which summarises the origin, place of maturation and activities
of some of the cells of the immune system.
Produced in?
Mature in?
Action?
Neutrophil
bone marrow
B lymphocyte
T lymphocyte
bone marrow
coordinate the immune system
5
Describe the special feature of the cell membranes of B and T lymphocytes.
6
Approximately how many different types of B lymphocyte does the human body possess?
7
Describe what happens when an antigen binds to a complementary protein receptor on a B lymphocyte.
8
Explain why the secondary response of the immune system is much faster than the primary response.
9
Draw a labelled diagram of an antibody molecule.
10
Which part of the antibody molecule binds to the antigen?
11
Describe two ways in which T lymphocytes are involved in the immune response.
12
Copy and complete the table below which describes different types of immunity:
Type of Immunity
Natural active
How acquired?
Long or short lasting?
Slow or rapid
protection?
Infection with
pathogen.
Natural passive
Artificial active
Artificial passive
Short lasting.
Slow protection.
13
What is a vaccine?
14
What is meant by “herd immunity”?
15
List four reasons why vaccination is not completely successful.
16
List four reasons why vaccination has eliminated smallpox.
17
List three reasons why measles has not been eliminated by vaccination.
18
What is an allergy?
19
The following phrases describe an allergic reaction. Rearrange the phrases into the correct order.
1
2
3
4
5
6
7
20
Wrong order
Allergens enter the body for a second time.
Antigens on the allergens bind to antibodies attached to the mast cells.
Antigens on the allergens cause specific B cells to produce antibodies.
Airways become inflamed.
Antibodies attach to mast cells lining the airways
Mast cells secrete histamine.
Allergens enter the body for the first time
Suggest two reasons for the increase in cases of asthma in the UK.
Immunity Answers
1
Describe three barriers which prevent pathogens from entering the body.
 The epithelia which cover the airways
 Hydrochloric acid which kills many bacteria in the stomach
 Blood clotting which stops entry of pathogens through cuts in the skin.
2
Draw labelled diagrams of a macrophage and a neutrophil to the same scale.
 Drawings from fig. 16.1
3
Describe phagocytosis by a neutrophil using the words: histamine, antibody, engulf and lysosome.
 Cells which are infected by pathogens releases histamine which attracts neutrophils.
Pathogens are then engulfed by the neutrophils. Antibodies may have become attached to the
antigens on the surface of the pathogens. This makes it easier for the neutrophils to recognise
the pathogens and adhere to their surface. Once engulfed, the pathogens are digested by
enzymes from the neutrophil lysosomes.
4
Copy and complete the following table which summarises the origin, place of maturation and activities
of some of the cells of the immune system.
Produced in?
Mature in?
Action?
Neutrophil
bone marrow
bone marrow
phagocytosis
B lymphocyte
bone marrow
bone marrow
synthesise
antibodies
T lymphocyte
bone marrow
thymus gland
coordinate the immune
system
5
Describe the special feature of the cell membranes of B and T lymphocytes.
 The cell membranes of B and T lymphocytes have protein receptors which are similar to
antibodies and have a complementary shape to specific antigens.
6
Approximately how many different types of B lymphocyte does the human body possess?
 There are approximately 10 million different types of B lymphocyte in the human body.
7
Describe what happens when an antigen binds to a complementary protein receptor on a B lymphocyte.
 When an antigen binds to a protein receptor on a B lymphocyte the B lymphocyte divides by
mitosis to form a clone. Some of the B cells in the clone develop into short-lasting plasma cells
which secrete antibodies into the plasma. Other B cells in the clone develop into long-lasting
memory cells which rapidly form more plasma cells and memory cells on subsequent contact
with the antigen.
8
Explain why the secondary response of the immune system is much faster than the primary response.
 The primary response of the immune system involves very few specific B cells so antibodies
are produced more slowly and in smaller numbers. The secondary response involves much
larger numbers of memory cells, so antibodies are produced in much larger numbers at a faster
rate.
9
Draw a labelled diagram of an antibody molecule.
 See fig. 16.9
10
Which part of the antibody molecule binds to the antigen?
 The variable region of the antibody molecule binds to the antigen.
11
Describe two ways in which T lymphocytes are involved in the immune response.
 T helper cells release cytokines which stimulate the activities of the B cells and the
macrophages.
 T killer cells secrete toxins which destroy infected cells and their pathogens.
12
Copy and complete the table below which describes different types of immunity:
Type of Immunity
Natural active
Natural passive
Artificial active
Artificial passive
How acquired?
Infection with pathogen.
Via placenta or breast
milk.
Vaccination with antigen.
Injection with antibodies.
Long or short lasting?
Long lasting.
Short lasting.
Slow or rapid protection?
Slow protection.
Rapid protection.
Long lasting.
Short lasting.
Slow protection.
Rapid protection.
13
What is a vaccine?
 A vaccine is a preparation containing antigens, for example from live microorganisms, from
dead or harmless ones, from harmless toxins, or from surface antigens only.
14
What is meant by “herd immunity”?
 Herd immunity occurs when a large number of people are vaccinated at the same time. This
prevents the pathogen from being transmitted within the population because there are no
longer any host individuals who act as reservoirs of infection.
15
List four reasons why vaccination is not completely successful.
 Some people do not respond to vaccination because they have a poor immune system. E.g.,
individuals with protein energy malnutrition.
 Some pathogens mutate regularly to produce new strains with different antigens. E.g., the
influenza virus.
 Larger pathogens have so many different genes for their surface antigens that a single vaccine
will not produce all the necessary antibodies. E.g. eukaryotic protoctists such as Plasmodium
and Trypanosoma.
 Some pathogens are hidden from the immune system by living inside the host’s cells. E.g.
Plasmodium parasitises red blood cells and liver cells. Vibrio, which causes cholera,
parasitises the intestines.
16
List four reasons why vaccination has eliminated smallpox.
 The variola virus causing smallpox was stable and did not mutate.
 The vaccine was made from a harmless similar virus which was “live”.
 The vaccine could be kept easily, even in tropical conditions.
 Infected people were easy to identify.
17
List three reasons why measles has not been eliminated by vaccination.
 Many children show a poor response to the vaccine.
 It can be difficult to give booster injections to children in large cities with high birth rate and
mobile populations.
 Measles is highly infectious and a very high percentage of the population needs to be
vaccinated before herd immunity is achieved,
18
What is an allergy?
 An allergy is an overreaction of the immune system to a harmless antigen.
19
The following phrases describe an allergic reaction. Rearrange the phrases into the correct order.
1
2
3
4
5
6
7
20
Wrong order
Allergens enter the body for a second time.
Antigens on the allergens bind to antibodies
attached to the mast cells.
Antigens on the allergens cause specific B cells
to produce antibodies.
Airways become inflamed.
Antibodies attach to mast cells lining the
airways
Mast cells secrete histamine.
Allergens enter the body for the first time
Correct order
Allergens enter the body for the first time.
Antigens on the allergens cause specific B cells
to produce antibodies.
Antibodies attach to mast cells lining the
airways.
Allergens enter the body for a second time.
Antigens on the allergens bind to antibodies
attached to the mast cells.
Mast cells secrete histamine.
Airways become inflamed.
Suggest two reasons for the increase in cases of asthma in the UK.
 An increase in the amount of air pollution by sulphur dioxide.
 An increase in cases of passive tobacco smoking.