Plant Disease


  • 1) The tobacco mosaic virus infects the chloroplasts of tobacco leaves, turning them yellow and white in a mosaic pattern. The image below shows an example of some leaves affected by the virus. How will the leaves’ change in colour from green to yellow limit the growth of the plant? 2 Marks



    Video Mark Scheme


  • 2) The leaves of an infected plant may become crinkled or curled up. Why might this happen? 2 Marks


    Video Mark Scheme


  • 3) Tobacco mosaic virus cannot be treated. Why is it important for the farmer to remove any infected plants? 1 Marks


    Video Mark Scheme


  • 4) Some of his other crops show evidence of stunted growth. What should the farmer do to improve this, and why? 2 Marks


    Video Mark Scheme


  • 5) Aphids are an extremely common pest in the UK. Aphids are capable of acting as a vector, thereby transferring microbial pathogens between many different species. They particularly infest roses and tomatoes. Gardeners will often cultivate ladybirds to control the spread of disease to their plants via aphids. Suggest how this may work, and give an advantage of using a natural pest control, as oppose to artificial pesticides. 2 Marks


    Video Mark Scheme


  • 6) Plants have many natural defences of their own to protect themselves from disease. Outline some of these physical, chemical and mechanical defences 6 Marks


    Video Mark Scheme



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