You can also encourage students to identify key issues in the preceding extract and devise their own questions or topics for discussion. Barley yellow dwarf disease is caused by a virus and take-all disease is caused by a fungus. Write a short paragraph outlining the differences between viruses and fungi. Write a short essay on Koch's postulates. Include the story of their development.
Students test the effect of moisture, lemon juice and sugar on the growth of bread mould.
Students recover water moulds from water and soil and examine them with a microscope. Students grow tissue from infected apples on plates of agar jelly. At the end of the experiments, dispose of all cultures safely. This activity includes three assignments and leads students through the thought process of determining whether or not a pathogen is the cause of disease. It discusses Koch's postulates and traditional epidemiological techniques used with human diseases.