1. Every organism has unique molecules on the surface of its cells.

• Define antigen.

• List example antigen molecules.

2. Pathogens can be species-specific although others can cross species barriers.

• Explain the “challenge and response” mechanism of specific immunity.

• Describe activation of helper T lymphocytes by the macrophage.

• Describe activation of B cell lymphocytes by the helper T cells.

3. B lymphocytes are activated by T lymphocytes in mammals. [Limit the immune response to mammals. ]

4. Activated B cells multiply to form clones of plasma cells and memory cells.

5. Plasma cells secrete antibodies.

6. Antibodies aid the destruction of pathogens.

7. White cells release histamine in response to allergens.

8. Histamines cause allergic symptoms.

9. Immunity depends upon the persistence of memory cells.

10. Vaccines contain antigens that trigger immunity but do not cause the disease.

11. Fusion of a tumour cell with an antibody-producing plasma cell creates a hybridoma cell.

12. Monoclonal antibodies are produced by hybridoma cells.

1. Smallpox was the first infectious disease of humans to have been eradicated by vaccination.

2. Monoclonal antibodies to HCG are used in pregnancy test kits.

3. Antigens on the surface of red blood cells stimulate antibody production in a person with a different blood group.

1. Analysis of epidemiological data related to vaccination programmes.