ATI RN
microbiology chapter 10 test bank Questions
Question 1 of 5
What is the function of teichoic acid in Gram-positive bacteria?
Correct Answer: A
Rationale: The correct answer is A: Cell wall rigidity. Teichoic acid in Gram-positive bacteria helps to maintain the structural integrity of the cell wall by providing rigidity and stability. It also plays a role in regulating the movement of ions across the cell membrane. Choices B, C, and D are incorrect because teichoic acid is not involved in energy production, spore formation, or motility in bacteria. It primarily functions in cell wall maintenance and integrity.
Question 2 of 5
A sputum smear from a patient with pneumonia revealed Gram-positive diplococci with pointed ends surrounded by capsules. What microorganism is most likely?
Correct Answer: A
Rationale: Step-by-step rationale: 1. Gram-positive diplococci with pointed ends indicate Streptococcus pneumoniae. 2. Presence of capsules supports the likelihood of S. pneumoniae. 3. S. pneumoniae is a common cause of pneumonia. 4. Klebsiella pneumoniae is Gram-negative and does not form diplococci. 5. Neisseria meningitidis typically causes meningitis, not pneumonia. 6. Staphylococcus aureus is Gram-positive but does not typically present as diplococci in pneumonia cases.
Question 3 of 5
A Gram-positive, spore-forming bacterium was isolated from a wound infection. The bacteria were anaerobic and produced gas. What is the likely causative agent?
Correct Answer: A
Rationale: The correct answer is A: Clostridium perfringens. This bacterium is Gram-positive, spore-forming, anaerobic, and produces gas. Clostridium perfringens is commonly associated with wound infections due to its ability to produce gas gangrene. Choice B: Bacillus anthracis is also a Gram-positive, spore-forming bacterium, but it does not typically produce gas in wound infections. Choice C: Clostridium botulinum is a spore-forming, anaerobic bacterium, but it is associated with foodborne botulism rather than wound infections. Choice D: Clostridium tetani is a spore-forming, anaerobic bacterium that causes tetanus, but it does not produce gas in wound infections.
Question 4 of 5
A patient presented with an abscess caused by Gram-positive cocci in clusters, catalase-positive and coagulase-positive. What is the causative agent?
Correct Answer: A
Rationale: Rationale: 1. Gram-positive cocci in clusters point to Staphylococcus or Micrococcus. 2. Catalase-positive eliminates Streptococcus. 3. Coagulase-positive distinguishes Staphylococcus aureus. 4. Thus, the causative agent is Staphylococcus aureus. Summary: - B: Streptococcus pyogenes is catalase-negative. - C: Enterococcus faecalis is catalase-negative. - D: Micrococcus luteus is catalase-positive but coagulase-negative.
Question 5 of 5
A patient presented with fever, malaise, and an ulcerated lesion. A Gram stain of the lesion revealed large, Gram-positive rods. What is the likely causative agent?
Correct Answer: A
Rationale: The correct answer is A: Bacillus anthracis. Bacillus anthracis is the likely causative agent as it is a Gram-positive rod-shaped bacterium known to cause ulcerated lesions with associated fever and malaise. Anthrax typically presents with these symptoms and fits the description given in the question. Clostridium perfringens (Choice B) causes gas gangrene and typically presents with different symptoms. Clostridium tetani (Choice C) causes tetanus and is not associated with ulcerated lesions. Bacillus cereus (Choice D) is known for causing food poisoning and does not typically present with the symptoms described in the question.