ATI RN
mastering microbiology test bank Questions
Question 1 of 5
Poxviruses are the largest viruses, almost visible on a light microscope.
Correct Answer: A
Rationale: The correct answer is A: TRUE. Poxviruses are indeed the largest viruses, ranging from 200-450 nm in size, which is close to the resolution limit of a light microscope. This makes them almost visible under a light microscope. The other choices are incorrect because poxviruses are not smaller or uncertain in size (choices B and C), nor are they partially visible - they are almost visible due to their relatively large size.
Question 2 of 5
A scientist identifies a strand of RNA that can be directly used to code for important viral proteins during viral replication. What have they found?
Correct Answer: C
Rationale: The correct answer is C: (+RNA). This indicates that the scientist found a positive-sense RNA strand that can be directly translated by host cell machinery to produce viral proteins. Positive-sense RNA can act as messenger RNA, allowing immediate protein synthesis during viral replication. Choice A (RNA major) and D (RNA minor) are not standard terms used to describe RNA strands in virology. Choice B (-RNA) indicates a negative-sense RNA strand, which requires transcription to form a complementary positive-sense strand before protein synthesis. Thus, the identification of a strand of RNA that directly codes for viral proteins aligns with the characteristics of a positive-sense RNA strand.
Question 3 of 5
Microscopy of a wound abscess revealed Gram-negative rods producing blue-green pigment with a distinctive odor of jasmine. What is the likely causative agent?
Correct Answer: A
Rationale: The correct answer is A: Pseudomonas aeruginosa. Pseudomonas aeruginosa is known for producing a blue-green pigment called pyocyanin, which gives the characteristic color seen in the wound abscess. The distinctive odor of jasmine is also a key feature of Pseudomonas aeruginosa. Proteus vulgaris (B) and Klebsiella pneumoniae (D) do not produce blue-green pigment or have a jasmine-like odor. Escherichia coli (C) typically does not produce blue-green pigment or have a jasmine-like odor.
Question 4 of 5
Which bacteria produce exotoxins that can cause severe gastrointestinal illness?
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. Each bacterium has specific exotoxins that can result in severe gastrointestinal symptoms. Therefore, all three choices are correct in producing exotoxins that can cause severe gastrointestinal illness.
Question 5 of 5
The main structure components of viruses are
Correct Answer: A
Rationale: The correct answer is A: nucleic acid and proteins. Viruses consist of genetic material (nucleic acid) surrounded by a protein coat. The nucleic acid carries the viral genetic information, while the proteins form the capsid that protects the genetic material. This combination is essential for the virus to infect host cells and replicate. Lipids (choice B) are not typically part of the main structure of viruses. Lipids are more commonly found in the host cell membrane. Lipids and proteins (choice C) may be present in the viral envelope but are not the main structural components. Proteins and glycoproteins (choice D) are important for viral attachment and entry into host cells but do not constitute the main structural components of viruses.