Transmission of animal and plant pathogens (OCR A-level Biology A)

This lesson describes the means of transmission of animal and plant communicable pathogens, including direct and indirect transmission. The PowerPoint and accompanying worksheets have been primarily designed to cover point 4.1.1 (b) of the OCR A-level Biology A specification but intricate planning ensures that the students are constantly challenged on their recall of the content of the previous lesson, where the different types of pathogens that cause communicable diseases in plants and animals was covered.

The lesson contains a wide range of tasks which will engage the students whilst challenging them to think about the biological content. Relevant examples such as the UK government’s public message of “HANDS, FACE, SPACE” are used to explain how TB and HIV are directly transmitted through droplet infection or the exchange of bodily fluids. A series of exam-style questions challenge the students on their knowledge of the transmission of HIV and the mark scheme is embedded into the PowerPoint to allow them to assess their progress. Students will learn that although HIV is mainly a sexually transmitted infection, the sharing of needles by intravenous drug users and vertical transmission from a mother to foetus (or baby) are other mechanisms for the spread.

Moving forwards, the next part of the lesson focuses on the transmission of cholera and malaria in unsafe water and through a vector respectively. Time is taken to emphasise the meaning of a vector and student understanding is checked later in the lesson when discussing the spread of the fungus responsible for Dutch elm disease by the elm beetle. The effect of climate and social factors are also considered, and the outbreak of cholera in Yemen in 2016 is used to introduce a number of the social determinants that affect transmission.

The final part of the lesson describes the direct and indirect means of transmission of plant pathogens and biological examples are sourced to increase the relevance.