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Immunity and disease
7 MDCAT Biology questions with answers and explanations.
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Antibodies are produced by:
- 1 Plasma cells
- 2 Red blood cells
- 3 Platelets
- 4 Neutrophils
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Correct answer: Plasma cells
When B lymphocytes are activated they become plasma cells, which make large amounts of antibody.
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Which blood group is the universal donor for red blood cells?
- 1 AB positive
- 2 O negative
- 3 A negative
- 4 B positive
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Correct answer: O negative
O negative red cells carry no A, B or Rh antigens, so they are unlikely to be attacked in the recipient.
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Rhesus incompatibility can cause problems in a pregnancy when:
- 1 The mother is Rh positive and the fetus is Rh negative
- 2 The mother is Rh negative and the fetus is Rh positive
- 3 Both are Rh negative
- 4 Both are Rh positive
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Correct answer: The mother is Rh negative and the fetus is Rh positive
An Rh negative mother can make antibodies against the Rh antigens of an Rh positive fetus.
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Which cells directly destroy virus-infected body cells?
- 1 Cytotoxic T cells
- 2 Plasma cells
- 3 Mast cells
- 4 Red blood cells
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Correct answer: Cytotoxic T cells
Cytotoxic T cells recognise infected cells and kill them.
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Which of these is an example of passive immunity?
- 1 Immunity after having measles
- 2 Immunity after a vaccine
- 3 Antibodies passed from mother to baby through breast milk
- 4 Immunity from a booster dose
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Correct answer: Antibodies passed from mother to baby through breast milk
In passive immunity the antibodies are received ready-made, so the baby makes no memory cells of its own.
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Malaria is caused by:
- 1 A virus
- 2 A bacterium
- 3 Plasmodium, a protozoan
- 4 A fungus
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Correct answer: Plasmodium, a protozoan
Plasmodium is spread by the bite of the female Anopheles mosquito.
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The dengue virus is spread by:
- 1 Anopheles mosquito
- 2 Aedes mosquito
- 3 House fly
- 4 Tsetse fly
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Correct answer: Aedes mosquito
Dengue is carried by Aedes mosquitoes, mainly Aedes aegypti.