ATI RN
microbiology chapter 1 test bank Questions
Question 1 of 5
The central dogma concerning the flow of information from genetic material was first introduced by
Correct Answer: B
Rationale: The central dogma of molecular biology, which describes the flow of genetic information from DNA to RNA to proteins, was first proposed by Francis Crick. Crick, along with James Watson, discovered the structure of DNA in 1953, leading to the understanding of how genetic information is stored and transmitted. Ernst Ruska was a physicist who developed the electron microscope, not related to genetic information flow. Camillo Golgi was an Italian biologist known for the discovery of the Golgi apparatus, not central to the central dogma. Carl Bender is not a prominent figure in the field of molecular biology. In summary, Francis Crick is the correct answer as he played a pivotal role in introducing the central dogma of molecular biology.
Question 2 of 5
A stool sample from a patient with severe diarrhea revealed non-lactose-fermenting, Gram-negative rods on Endo agar. What is the likely causative agent?
Correct Answer: A
Rationale: The correct answer is A: Shigella dysenteriae. It is the likely causative agent because it is a non-lactose-fermenting, Gram-negative rod commonly associated with severe diarrhea. Shigella dysenteriae specifically causes bacillary dysentery. Other choices are incorrect because:
B: Escherichia coli is a lactose-fermenting bacterium commonly found in the gut and not typically associated with severe diarrhea.
C: Salmonella typhi causes typhoid fever, not severe diarrhea.
D: Proteus mirabilis is a urease-positive bacterium associated with urinary tract infections, not severe diarrhea.
Question 3 of 5
Microscopy of a wound smear revealed Gram-positive rods with terminal spores resembling drumsticks. What microorganism is most likely responsible?
Correct Answer: A
Rationale: The correct answer is A: Clostridium tetani. The presence of Gram-positive rods with terminal spores resembling drumsticks indicates Clostridium tetani, the causative agent of tetanus. This bacterium forms spores at one end, giving it a drumstick appearance under the microscope. Clostridium perfringens (
B) and Clostridium botulinum (
D) do not have terminal spores. Bacillus anthracis (
C) forms spores but typically appears as a square-ended or bamboo stick shape.
Therefore, based on the microscopy findings, Clostridium tetani is the most likely microorganism responsible for the wound infection.
Question 4 of 5
Detection of galactomannan and free mannan is used for diagnosing
Correct Answer: A
Rationale: The correct answer is A: aspergillosis and candidiasis. Detection of galactomannan and free mannan is commonly used in diagnosing these fungal infections. Galactomannan is a component of the cell wall of Aspergillus species, while free mannan is associated with Candida species. This detection method helps in identifying these specific fungal infections accurately.
B: Syphilis is caused by a bacterium, Treponema pallidum, and is not diagnosed using galactomannan or free mannan detection.
C: Leptospirosis is a bacterial infection caused by the Leptospira species and is not diagnosed using galactomannan or free mannan detection.
D: HIV infection is a viral infection caused by the human immunodeficiency virus and is not diagnosed using galactomannan or free mannan detection.
Question 5 of 5
The capsule of the bacteria is composed of:
Correct Answer: B
Rationale: The correct answer is B because the capsule of bacteria is mainly composed of polysaccharides or polypeptides. This outer layer helps bacteria evade the host's immune system and protects them from desiccation. Peptidoglycan (choice
A) is a component of the bacterial cell wall, not the capsule. Flagellin (choice
C) is a protein component of the bacterial flagella, not the capsule.
Choice D is incorrect as the capsule is indeed composed of polysaccharides or polypeptides.