MICROBIOLOGY AND PARASITOLOGY MCQs

47 clinical MCQs in Microbiology. Which one of the following is an intracellular parasite? —. Kenya, Africa and global revision.

Questions, Answers & Explanations

1. Q1. Which one of the following is an intracellular parasite? ---

   • Trypanosoma brucei rhodesiense
   • Trichomonas vaginalis
   • Entamoeba histolytica
   • Leishmania donovani
   • All of the above

   Answer: Leishmania donovani

2. Q2. Parasites can be classified based on their hosts. Which one of the following statements classifies a Mesoparasite ? ---

   • A parasite which is occasionally found in both intermediate and definitive host
   • A parasite which entirely lives in an intermediate host
   • A parasite which entirely lives in a definitive host
   • A parasite which partly lives in and on a host
   • None of the above

   Answer: A parasite which partly lives in and on a host

3. Q3. Single-celled parasites utilize various physiological modes to take in molecules. Which one of the following is adopted for intake of a molecule for mutualism existence within the parasite? ---

   • Endocytosis
   • Active transport
   • Pinocytosis
   • Exocytosis
   • None of the above

   Answer: Endocytosis

4. Q4. The following are genetic-based conditions which can lead to resistance against malaria infection EXCEPT ? ---

   • Sickle cell trait
   • Thalassemia
   • Presence of Glucose-6-phosphate dehydrogenase
   • Absence of Duffy antigens
   • None of the above

   Answer: Presence of Glucose-6-phosphate dehydrogenase

5. Q5. In which form does Fasciola hepatica get into the human host? ---

   • Eggs
   • Cercariae
   • Trophozoites
   • Metacercariae
   • Larvae

   Answer: Metacercariae

6. Q6. Malaria infection is characterized by paroxysms. What is the interval of these paroxysms in a Plasmodium vivax infection? ---

   • 24 hours
   • 96 hours
   • 48 hours
   • 72 hours
   • 12 hours

   Answer: 48 hours

7. Q7. Which of the following parasites can be diagnosed by cerebrospinal fluid biopsy? ---

   • Giardia lamblia
   • Ascaris lumbricoides
   • Trichinella spiralis
   • Taenia solium
   • All of the above

   Answer: Taenia solium

8. Q8. Trichomonas vaginalis is characterized by how many flagella? ---

   • Five
   • Four
   • Three
   • Two
   • Six

   Answer: Five

9. Q9. Which of the following is NOT true about bacterial flagella? ---

   • Most of their length consists of a hollow, rigid protein tube.
   • They are constructed largely of a single protein called flagellin.
   • They spin like wheels, either clockwise or counterclockwise.
   • They use cytoplasmic ATP as their primary energy source.
   • None of the above

   Answer: They use cytoplasmic ATP as their primary energy source.

10. Q10. What is the purpose of bacterial endospores? ---

    • Allow the bacterium to make hundreds of "seeds" to spread on the wind.
    • Help the bacterium differentiate into faster-growing stages.
    • Allow the bacterium to survive the absence of oxygen.
    • Allow the bacterium to survive extended periods of heat or dryness.
    • All of the above

    Answer: Allow the bacterium to survive extended periods of heat or dryness.

11. Q11. Cells containing many nuclei are called ---

    • Coenocyte
    • Hyphae
    • Mycelium
    • Sporophore
    • None of the above

    Answer: Coenocyte

12. Q12. The group or mass of hyphae is ---

    • Coenocyte
    • Hyphae
    • Mycelium
    • Sporophore
    • B and C

    Answer: B and C

13. Q13. The spores produced inside the sporangia are ---

    • Conidia
    • Endospore
    • Zoospore
    • Sporangiospores
    • Microspores

    Answer: Sporangiospores

14. Q14. The spores produced at the tip of hyphae outside the sporangia are ---

    • Conidia
    • Endospore
    • Zoospore
    • Oidia
    • Sporangiospores

    Answer: Conidia

15. Q15. In some fungi, the hyphae break up into individual cells. These cells behave as spores and are called ---

    • Blastospores
    • Endospore
    • Zoospore
    • Arthrospores
    • Conidiaspores

    Answer: Arthrospores

16. Q16. The most crucial step in infection of a host cell by a virus is ---

    • Adsorption
    • Attachment
    • Penetration
    • Replication
    • Release

    Answer: Penetration

17. Q17. The viral nucleocapsid is the combination of ---

    • Genome and capsid
    • Capsid and spikes
    • Envelope and capsid
    • Capsomere and genome
    • Genome and spikes

    Answer: Genome and capsid

18. Q18. In the absence of cytopathic effects (CPE), how would one demonstrate that a permissive cell is infected by a virus? ---

    • By Immunofluorescence Test (IFT)
    • By plaque test
    • By cell counting
    • By hemagglutination assay
    • None of the above

    Answer: By Immunofluorescence Test (IFT)

19. Q19. What is a phage? ---

    • Bacterium that infects viruses
    • A virus that infects bacteria
    • A bacterium that infects animal cells
    • An arbovirus
    • Virus-transformed cell

    Answer: A virus that infects bacteria

20. Q20. Prevention of viral diseases is best achieved by ---

    • Antibiotics
    • Use of condoms
    • Vaccination
    • Antiviral drugs
    • All of the above

    Answer: Vaccination

21. Q21. A chemical component that is found in all viruses is ---

    • Protein-coated nucleic acid
    • Lipid
    • DNA
    • RNA
    • All of the above

    Answer: Protein-coated nucleic acid

22. Q22. Interferons are ---

    • Synthesized by the virus when infecting a cell
    • Synthesized by the host cell when infected by a virus
    • Synthesized by defective particles during infection
    • Synthesized by subviral agents in the cell during infection
    • A and B

    Answer: Synthesized by the host cell when infected by a virus

23. Q23. During what stage of the viral life cycle is the nucleic acid packed inside the capsid? ---

    • Penetration
    • Late protein synthesis (capsid)
    • Early protein synthesis
    • Assembly
    • At the time of uncoating

    Answer: Assembly

24. Q24. Which types of viruses contain reverse transcriptase? ---

    • Herpes viruses
    • Adenoviruses
    • Influenza viruses
    • Retroviruses
    • All single-stranded RNA viruses

    Answer: Retroviruses

25. Q25. A phage that exhibits both lytic and lysogenic life cycles is called ---

    • Prophage
    • Provirus
    • Virulent
    • Temperate
    • Plaque

    Answer: Temperate

26. Q26. In which type of virus is the production of double-stranded DNA from RNA a necessary intermediate in the life cycle? ---

    • Influenza virus
    • Polio virus
    • Herpes virus
    • Retrovirus
    • T-even phage

    Answer: Retrovirus

27. Q27. The significance of the plasma membrane is that ---

    • It selectively allows some molecules to pass into the organism.
    • It prevents movement of molecules out of the organism.
    • It is the site of protein synthesis.
    • B and C
    • All of the above

    Answer: It selectively allows some molecules to pass into the organism.

28. Q28. Commonly encountered bacteria are roughly spherical. The microbiological term describing this shape is ---

    • Coccus
    • Coccobacillus
    • Pleomorphic
    • None of the above
    • Coccus and sometimes coccobacillus

    Answer: Coccus

29. Q29. Another common bacterial shape is that of a rod, often called ---

    • Coccus
    • Bacillus
    • Pleomorphic
    • Vibrio
    • None of the above

    Answer: Bacillus

30. Q30. In bacterial cells, ribosomes are packed into the cytoplasmic matrix and also loosely attached to the plasma membrane. What is the function of ribosomes? ---

    • Site of energy production
    • Site of protein synthesis
    • Site of genetic reproduction
    • Both A and B
    • None of the above

    Answer: Site of protein synthesis

31. Q31. What is a plasmid? ---

    • Self-replicating segment of double-stranded DNA
    • Self-replicating segment of single-stranded RNA
    • A bacterial chromosome
    • All of the above
    • None of the above

    Answer: Self-replicating segment of double-stranded DNA

32. Q32. Plasmids are important to the genetics of many bacteria because ---

    • They are inherited from one generation to the next.
    • They may carry genes that give their host a selective advantage.
    • They can render bacteria drug-resistant.
    • All of the above.
    • They facilitate lysogeny.

    Answer: All of the above.

33. Q33. Some bacteria are considered pleomorphic. This means ---

    • They are shaped like bent rods.
    • They have a corkscrew shape.
    • They do not have just one shape.
    • They are restricted to one biotope.
    • They are not either bacilli or cocci.

    Answer: They do not have just one shape.

34. Q34. The 70S prokaryotic ribosomes consist of ---

    • Two 40S subunits.
    • A 50S and a 30S subunit.
    • A 40S and a 30S subunit.
    • A 50S and a 20S subunit.
    • A 20S and a 60S subunit.

    Answer: A 50S and a 30S subunit.

35. Q35. Gram-positive cells:A) Have thick, homogeneous cell walls. ---

    • Have large amounts of teichoic acids.
    • Have large molecular chitins.
    • Do not have an outer membrane.
    • All of the above are true.
    • Occurs only after chronic exposure

    Answer: Have large amounts of teichoic acids.

36. Q36. The outer membrane of Gram-negative cells is more permeable than the plasma membrane because:A) LPS is larger than most membrane phospholipids. ---

    • Lipoproteins stretch the outer membrane.
    • Porin proteins establish holes in the outer membrane.
    • The core polysaccharide spans the lipid bilayer.
    • None of the above.
    • Limited to a single tissue compartment

    Answer: Lipoproteins stretch the outer membrane.

37. Q37. The most important role of the prokaryotic cell wall is to:A) Maintain the shape of the cell. ---

    • Protect the cell from osmotic pressures.
    • Prevent ions from diffusing away from the cell.
    • Block the effects of antibiotics like penicillin.
    • All of the above.
    • Primarily an incidental laboratory finding

    Answer: Protect the cell from osmotic pressures.

38. Q38. Which of the following is NOT true about capsules and slime layers?A) They consist of secreted material lying outside of the bacterial cell wall. ---

    • They can prevent desiccation of bacterial cells.
    • They are required for bacteria to grow normally in culture.
    • They help bacteria resist phagocytosis by macrophages.
    • None of the above.
    • Usually mediated by non-specific mechanisms

    Answer: They can prevent desiccation of bacterial cells.

39. Q39. Fimbriae:A) Attach bacteria to various surfaces. ---

    • Cause bacteria to move through fluids.
    • Sense changes in nutrient concentration.
    • Are pathways for the secretion of exoenzymes.
    • C and D.
    • Mostly unchanged in early disease

    Answer: Cause bacteria to move through fluids.

40. Q40. A bacillus bacterium with a single flagellum at each end is described as:A) Monotrichous ---

    • Amphitrichous
    • Lophotrichous
    • Peritrichous
    • All of the above
    • Reduced by routine feedback control

    Answer: Amphitrichous

41. Q41. Bacterial capsules are useful for:A) Attachment to surfaces. ---

    • Protection against macrophages.
    • Production of toxins.
    • Motility.
    • Reproduction.
    • Occurs only after chronic exposure

    Answer: Protection against macrophages.

42. Q42. Which of the following is a true pathogen?A) Candida ---

    • Sporothrix
    • Mucor
    • Aspergillus
    • None
    • Limited to a single tissue compartment

    Answer: Sporothrix

43. Q43. Bacterial capsules are best demonstrated by:A) Methylene blue stain. ---

    • Gram stain.
    • Negative staining.
    • Impregnation technique.
    • None of the above.
    • Primarily an incidental laboratory finding

    Answer: Gram stain.

44. Q44. In a light microscope, what function does the condenser serve?A) Focuses the light rays on the sample. ---

    • Magnifies the light rays after their passage through the sample.
    • Focuses the light rays into the observer’s eyes.
    • Increases the light intensity.
    • Reduces glare.
    • Usually mediated by non-specific mechanisms

    Answer: Magnifies the light rays after their passage through the sample.

45. Q45. One of the diseases below is not caused by bacteria:A) Leprosy ---

    • Plague
    • Rabies
    • Tetanus
    • Meningitis
    • Mostly unchanged in early disease

    Answer: Plague

46. Q46. The presence of D-amino acids in the crosslinks of the peptidoglycan layer is most likely because:A) Most peptidases can only cleave L-amino acids. ---

    • D-amino acids fit the structural constraints of the cell wall better than L-amino acids.
    • Most L-amino acids have already been used for protein synthesis.
    • D-amino acids are easier to crosslink in the absence of ribosomes.
    • They promote synthesis of much-needed essential amino acids.
    • Reduced by routine feedback control

    Answer: D-amino acids fit the structural constraints of the cell wall better than L-amino acids.

47. Q47. Which of the following is not a characteristic of fungi?A) Can be unicellular or multicellular.

    • Have cell walls made of chitin.
    • Are photosynthetic.
    • Can produce antibiotics.
    • Can be infected by viruses.
    • Occurs only after chronic exposure

    Answer: Have cell walls made of chitin.