All of the statements about Rotaviruses are correct EXCEPT
- A. non-specific antiviral therapy is available
- B. Rotaviruses are ubiquitous worldwide
- C. Rotaviruses are a major cause of meningitis
- D. large amounts of viruses are released in fecal matter
Correct Answer: C
Rationale: The correct answer is C because Rotaviruses are not a major cause of meningitis; they primarily cause gastroenteritis. This is because Rotaviruses infect the gastrointestinal tract, not the central nervous system. Choice A is incorrect because there is no specific antiviral therapy for Rotaviruses. Choice B is correct as Rotaviruses are indeed widespread globally. Choice D is correct as Rotaviruses are shed in large amounts in feces, contributing to their ability to spread easily.
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The main function of bacterial ribosomes is:
- A. DNA replication
- B. protein synthesis
- C. cell wall synthesis
- D. RNA splicing
Correct Answer: B
Rationale: The correct answer is B: protein synthesis. Bacterial ribosomes are responsible for translating messenger RNA into proteins through a process called translation. Ribosomes are composed of both protein and RNA molecules and facilitate the binding of transfer RNA to the messenger RNA to assemble the amino acids in the correct order to form a protein. DNA replication (A) is carried out by enzymes such as DNA polymerase, not ribosomes. Cell wall synthesis (C) is a process involving enzymes that build the structure of the cell wall in bacteria. RNA splicing (D) is a eukaryotic process that involves removing introns from pre-mRNA molecules, which is not a function of bacterial ribosomes.
All of the following areas of the human body contain normal flora except:
- A. Peritoneum
- B. Urethra
- C. Vagina
- D. Mouth
Correct Answer: A
Rationale: The correct answer is A: Peritoneum. Normal flora refers to the microorganisms that naturally inhabit the human body without causing harm. The peritoneum is a sterile area, so it does not harbor normal flora. The urethra, vagina, and mouth all have normal flora due to their moist and warm environments, which provide an ideal habitat for microorganisms to thrive. The peritoneum, being a sterile cavity that houses organs like the stomach and intestines, does not have a natural microbial population like the other areas mentioned. Therefore, it does not contain normal flora.
Pseudomonas aeruginosa can cause:
- A. Burn wounds infection, severe pneumonia in patients with cystic fibrosis, nosocomial infections
- B. Food poisoning
- C. Bacterial pharyngitis
- D. None of the above
Correct Answer: A
Rationale: Step-by-step rationale for answer A:
1. Pseudomonas aeruginosa is known to cause burn wounds infections due to its ability to survive in moist environments.
2. It can cause severe pneumonia in patients with cystic fibrosis due to its resistance to antibiotics and ability to form biofilms.
3. It is a common cause of nosocomial infections in hospitals due to its ability to colonize medical equipment and surfaces.
Summary of other choices:
B. Pseudomonas aeruginosa typically does not cause food poisoning, as it is not a common pathogen associated with foodborne illnesses.
C. Bacterial pharyngitis is usually caused by Streptococcus pyogenes, not Pseudomonas aeruginosa, making this choice incorrect.
D. None of the above is incorrect as Pseudomonas aeruginosa is associated with specific infections mentioned in option A.
The Baltimore classification system places viruses into __________ groups.
- A. four
- B. five
- C. seven
- D. nine
Correct Answer: C
Rationale: The Baltimore classification system categorizes viruses based on their genome type and replication strategy. It divides viruses into seven groups: Group I (dsDNA), Group II (ssDNA), Group III (dsRNA), Group IV (ssRNA(+)), Group V (ssRNA(-)), Group VI (ssRNA-RT), and Group VII (dsDNA-RT). Each group represents a distinct viral genome and replication method. Therefore, the correct answer is C. The other choices are incorrect because the Baltimore classification system specifically identifies viruses into seven groups, not four, five, or nine.
A patient with a sore throat had a throat smear stained by Neisser's method. Microscopy revealed rods with polar dark blue granules. What microorganism is likely responsible?
- A. Corynebacterium diphtheriae
- B. Bacillus anthracis
- C. Clostridium tetani
- D. Escherichia coli
Correct Answer: A
Rationale: The presence of rods with polar dark blue granules stained by Neisser's method indicates metachromatic granules consistent with Corynebacterium diphtheriae. The characteristic staining pattern is due to the presence of polar granules in the bacterial cells, a feature specific to Corynebacterium diphtheriae. Bacillus anthracis, Clostridium tetani, and Escherichia coli do not exhibit this staining pattern or morphology typical of Corynebacterium diphtheriae, making them incorrect choices.