Other pathogens: stem rust, influenza and malariaEdexcel A-Level Biology B: Flashcards

Exam questions on Other pathogens: stem rust, influenza and malaria

1. A wheat farmer finds red-brown pustules on the stems and leaves of her crop. Hyphae of the fungus Puccinia graminis are seen growing through the leaf tissue under a microscope. Spores from the pustules are carried across neighbouring fields, and the infected plants produce small, shrivelled grains and a much lower yield.
   Explain why wheat plants infected with Puccinia graminis produce a lower yield of grain.2 marks
2. Over three days, many pupils in a school develop fever, aching muscles and a dry cough. Swabs show influenza virus, an enveloped RNA virus, in the cells lining the nose and throat of the pupils. One pupil later develops a bacterial chest infection.
   Explain why influenza makes a patient more likely to develop a bacterial chest infection.2 marks
3. A traveller returns from a region where malaria is endemic. Ten days later she develops a fever that returns every two to three days, and she feels weak and pale. A blood test shows a low haemoglobin concentration, and Plasmodium parasites are seen inside her red blood cells.
   Describe how the traveller became infected with Plasmodium.3 marks