Communicable diseases: immune system defence, treatment and prevention
GCSE Biology students need to understand the fundamental concept that communicable diseases are an interaction between a particular pathogen and the body's various defence mechanisms. They need to be able to explain how such diseases are spread and should be able to describe a common human infection. Students should also know about sexually transmited infections in humans including HIV/AIDS. For these diseases students should be able to explain how the spread of these may be reduced or prevented.
Students will need to be able to describe the non-specific defence mechanisms of the human body, in terms of what these mechanisms are and the fact that they do not distinguish between one type of pathogen and another. This will then lead onto students being able to describe the specific defence mechanisms in terms of the role of the immune system. In terms of treatments related to communicable diseases, students should be able to describe how monoclonal antibodies are produced and how they can be used. They should also be able to explain the use of vaccines.
In delivering this topic, students understanding of pathogens needs to be confirmed. Often students do not seem to appreciate that there are different types of pathogens, i.e bacteria and viruses. It is worth spending time on this area before moving onto non-specific and specific defence mechanisms. Using a range of illustrations/images and asking students to prepare annotated diagrams of different pathogens will support learning. A common misconception is how communicable diseases are spread, students do not always appreciate the different modes of transmission of different pathogens, so ensure they complete activities to support this understanding.
Students often display confusion between with use of antibiotics and the use of vaccines, a misconception being that vaccines are possible alternatives to the use of antibiotics. It would be worth developing some comparison activities for these two ways to treat/prevent communicable diseases. Students could be given website links-one on antibiotics and one on vaccines - then asked to note five key bullet points from what they have read.
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