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Infectious Disease: Question 1

Syllabus 10.1

Multiple choice AS 1 mark

Cholera, malaria, tuberculosis and HIV/AIDS are all infectious diseases, but each is caused by a different type of pathogen.

Which option correctly identifies the type of organism that causes each of these four diseases?

Choose an answer to check it, then compare with the worked solution below.
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Worked solution

Step 1: Recall the pathogen and pathogen type for each disease

  • Cholera is caused by Vibrio cholerae, a bacterium.
  • Malaria is caused by Plasmodium, a protoctist (protozoan), several species infect humans, transmitted by a mosquito vector.
  • Tuberculosis is caused mainly by Mycobacterium tuberculosis (sometimes M. bovis), a bacterium.
  • HIV/AIDS is caused by the human immunodeficiency virus (HIV), a virus.

Step 2: Evaluate each option against this list

  • A: bacterium (cholera), protoctist (malaria), bacterium (tuberculosis), virus (HIV/AIDS), this matches every disease correctly.
  • B: incorrect. Wrongly gives cholera as a virus (it is a bacterium) and HIV/AIDS as a bacterium (it is a virus).
  • C: incorrect. Wrongly swaps malaria and tuberculosis, giving malaria as a virus (it is a protoctist) and tuberculosis as a protoctist (it is a bacterium).
  • D: incorrect. Wrongly gives cholera as a protoctist, malaria as a bacterium and tuberculosis as a virus; only HIV/AIDS is also wrong here (given as a bacterium).

Final answer

  • Cholera (bacterium), malaria (protoctist), tuberculosis (bacterium) and HIV/AIDS (virus) are all correctly matched only in option A.