Risks associated with scientific research—Florey and Chain’s tests on the safety of penicillin would not be compliant with current protocol on testing. (4.8)
Understandings:
The skin and mucous membranes form a primary defence against pathogens that cause infectious disease. [Diagrams of skin are not required.]
Cuts in the skin are sealed by blood clotting. Clotting factors are released from platelets. The cascade results in the rapid conversion of fibrinogen to fibrin by thrombin.
Ingestion of pathogens by phagocytic white blood cells gives non-specific immunity to diseases.
Production of antibodies by lymphocytes in response to particular pathogens gives specific immunity.(students should be aware that some lymphocytes act as memory cells and can quickly reproduce to form a clone of plasma cells if a pathogen carrying a specific antigen is re-encountered.]
Antibiotics block processes that occur in prokaryotic cells but not in eukaryotic cells.
Viruses lack a metabolism and cannot therefore be treated with antibiotics. Some strains of bacteria have evolved with genes that confer resistance to antibiotics and some strains of bacteria have multiple resistance.
Applications and Skills:
Causes and consequences of blood clot formation in coronary arteries.
Florey and Chain’s experiments to test penicillin on bacterial infections in mice.
Effects of HIV on the immune system and methods of transmission. [The effects of HIV on the immune system should be limited to a reduction in the number of active lymphocytes and a loss of the ability to produce antibodies, leading to the development of AIDS.]