Nokea
Which of the following best describes the role of bacterial plasmids?
- A. Regulation of bacterial growth
- B. Carrying antibiotic resistance genes
- C. Producing toxins
- D. Facilitating endospore formation
Correct Answer: B
Rationale: The correct answer is B: Carrying antibiotic resistance genes. Bacterial plasmids are small, circular DNA molecules that can carry genes, including those for antibiotic resistance. This allows bacteria to survive exposure to antibiotics. Plasmids do not directly regulate bacterial growth (A), produce toxins (C), or facilitate endospore formation (D). Plasmids play a crucial role in the spread of antibiotic resistance among bacteria.
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Which bacteria are known for producing toxins that can cause severe gastrointestinal illness?
- A. Clostridium botulinum
- B. Vibrio cholerae
- C. Escherichia coli
- D. All of the above
Correct Answer: D
Rationale: The correct answer is D, "All of the above." Clostridium botulinum produces botulinum toxin causing botulism, Vibrio cholerae produces cholera toxin leading to severe diarrhea, and certain strains of Escherichia coli produce toxins causing gastrointestinal illness. Therefore, all three bacteria are known for producing toxins that can cause severe gastrointestinal illness. Choices A, B, and C individually represent bacteria known for producing toxins that can cause severe gastrointestinal illness, making them incorrect individual choices.
Mycobacteria have in their cell walls:
- A. High amount of polysaccharides
- B. High amount of lipids
- C. High amount of mycolic acids
- D. High amount of proteins
Correct Answer: C
Rationale: The correct answer is C: High amount of mycolic acids. Mycobacteria are characterized by their unique cell wall composition, which includes a high amount of mycolic acids. Mycolic acids provide the bacteria with resistance to environmental stresses and are crucial for their pathogenicity. Polysaccharides (A) are not a prominent component of mycobacterial cell walls. While lipids (B) are present in mycobacterial cell walls, mycolic acids are the predominant lipid. Proteins (D) are also present but are not the defining feature of mycobacterial cell walls. Therefore, the correct answer is C due to the significant role mycolic acids play in the structure and function of mycobacterial cell walls.
Which of the following bacteria is responsible for causing bacterial meningitis?
- A. Neisseria meningitidis
- B. Haemophilus influenzae
- C. Streptococcus pneumoniae
- D. All of the above
Correct Answer: D
Rationale: The correct answer is D because all three bacteria (Neisseria meningitidis, Haemophilus influenzae, and Streptococcus pneumoniae) can cause bacterial meningitis. Neisseria meningitidis is a common cause of meningococcal meningitis, Haemophilus influenzae can cause H. influenzae meningitis, and Streptococcus pneumoniae is a leading cause of pneumococcal meningitis. Therefore, all of the above choices are correct. The other choices are incorrect because each of the bacteria listed can independently cause bacterial meningitis, so none of them alone can be the sole correct answer.
The following viruses are referred to the Filoviridae family:
- A. Lassa virus and lymphocytic choriomeningitis viruses
- B. Chikungunya virus and Sindbis virus
- C. Marburg virus and Ebola virus
- D. Crimean-Congo virus and Hantaan virus
Correct Answer: C
Rationale: Step-by-step rationale:
1. The Filoviridae family includes Marburg virus and Ebola virus.
2. Both viruses are characterized by filamentous, enveloped structure.
3. They cause severe hemorrhagic fever in humans.
4. Lassa virus and lymphocytic choriomeningitis viruses belong to Arenaviridae.
5. Chikungunya virus and Sindbis virus are alphaviruses.
6. Crimean-Congo virus and Hantaan virus are bunyaviruses.
7. Therefore, the correct answer is C.
A patient with suspected liver abscess was admitted to the surgical department. The patient had been staying for a long time on business in one of African countries and fell repeatedly ill with acute gastrointestinal disorders. What protozoal disease may the patient be now ill with?
- A. Amebiasis
- B. Trypanosomosis
- C. Leishmaniasis
- D. Malaria
Correct Answer: A
Rationale: Rationale: The correct answer is Amebiasis (choice A) because the patient's symptoms of acute gastrointestinal disorders and prolonged stay in an African country suggest exposure to Entamoeba histolytica, the causative agent of amebiasis. This protozoal infection commonly occurs in tropical regions, including Africa. Trypanosomosis (choice B) is caused by Trypanosoma species transmitted by tsetse flies, primarily found in sub-Saharan Africa. Leishmaniasis (choice C) is transmitted by sandflies and presents with skin lesions or visceral involvement, not acute gastrointestinal symptoms. Malaria (choice D) is caused by Plasmodium parasites transmitted by mosquitoes and typically presents with fever, not acute gastrointestinal disorders. Therefore, choices B, C, and D are incorrect based on the patient's clinical presentation and travel history.