Chapter 2 - Immunity Past Paper Questions

Question 1

Past Paper Question - CCEA A21 May 2016 Q6 a) [9]
Q6 Activation of the human immune system can have both positive and negative consequences.
Vaccination was first carried out by Edward Jenner in 1796. Many countries now have vaccination programmes.

Meningitis is a disease which can be caused by a bacterium referred to as Meningococcal B. Each year 1 in 10 of the 1200 people in the UK who get meningitis caused by this bacterium will die. In 2015 the vaccination programme for children in the UK was widened to include Meningococcal B vaccine. The vaccine contains an inactive form of the bacterium.

a) With reference to the human immune system, explain how Meningococcal B vaccination will result in fewer children suffering the effects of meningitis. [9]

Answer 1

Any nine from:
• This is an example of active immunity/ active immunity provides long term immunity
• Antibody-mediated immunity
• Antigens (of the Meningococcal B bacterium) present in the vaccine
• B-lymphocytes are sensitised
• B-lymphocytes divide rapidly by mitosis/clones form
• Plasma cells and memory cells are formed
• Plasma cells produce antibodies
• The antibodies are complementary to the antigens/ attach to the antigens/ an antigen-antibody complex is formed causing clumping/agglutination
• Memory cells will only be activated in the presence of specific (Meningococcal B bacterium) antigen/bacterium/pathogen
• If stimulated they will divide rapidly producing large numbers of plasma cells
• These plasma cells produce antibodies very quickly/secondary immune response is much quicker
• Appropriate reference to phagocytosis with regards the clump being engulfed

Question 2

Past Paper Question- CCEA A21 May 2016 Q6 b)

Answer 2

Any seven from:
• rhesus negative mothers do not have the rhesus antigen/antigen D on their red blood cells/erythrocytes
• a rhesus negative mother is pregnant with a rhesus positive baby
• during/before birth some foetal red blood cells/cell fragments/antigen D can be transferred to the mother
• mother’s immune system will produce anti-D antibodies
• the baby will be born before these antibodies are produced in large numbers/ antibodies produced slowly so will not be affected
• subsequent pregnancies may be affected as memory cells have remained in the mother’s blood
• antibodies may be produced immediately and cross the placenta/ transfer to foetus causing agglutination/clumping of the foetal red blood cells/haemolytic disease (of the newborn)
• anti-D antibodies (present in injection) attach to any antigen-D foetal red blood cells which cross the placenta/ transferred to the mother
• before the B-lymphocytes are stimulated
• (as B-lymphocytes aren’t stimulated) no plasma or memory cells are produced/ no immune response.