Free Microbiology Test Bank Questions PDF

Free Microbiology Test Bank Questions PDF Related

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After a prolonged isoniazid treatment, the patient developed polyneuritis, paresthesia, memory disorders, and convulsions. What is the most likely mechanism of the described isoniazid side-effects?

  • A. Disruption of cell membrane synthesis
  • B. Inhibition of protein synthesis
  • C. Inhibition of RNA-synthesis
  • D. Inhibition of pyridoxal phosphate synthesis
Correct Answer: D

Rationale: The correct answer is D. Isoniazid inhibits pyridoxal phosphate synthesis, which is the active form of vitamin B6. Pyridoxal phosphate is essential for various enzymatic reactions, including neurotransmitter synthesis and myelin formation. Therefore, isoniazid-induced pyridoxal phosphate deficiency can lead to neurological symptoms like polyneuritis, paresthesia, memory disorders, and convulsions.

A: Disruption of cell membrane synthesis - This is not the mechanism of isoniazid side-effects.
B: Inhibition of protein synthesis - Isoniazid does not directly inhibit protein synthesis.
C: Inhibition of RNA-synthesis - Isoniazid does not inhibit RNA synthesis; it affects vitamin B6 metabolism.

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The correct hierarchical order for virus classification is

  • A. order, genus, family, subfamily, species.
  • B. species, genus, family, subfamily, order.
  • C. order, family, subfamily, genus, species.
  • D. genus, order, family, subfamily, species.
Correct Answer: C

Rationale: The correct hierarchical order for virus classification is order, family, subfamily, genus, species. This is because classification starts at a broader level (order) and narrows down to a more specific level (species). Order comes first to group viruses based on common characteristics, followed by family, which further categorizes them. Subfamily refines the classification, then genus groups similar viruses together, and species distinguishes different strains within a genus. Choice A is incorrect because it places genus before family, which is not the correct sequence. Choice B is incorrect as it starts with species, which is the most specific level. Choice D is incorrect because it places genus at the beginning, which is too specific for the hierarchical order.

Routes for transmission of nosocomial infections are

  • A. air droplets and fecal-oral mechanism
  • B. air droplets and contact mechanism
  • C. parenteral mechanism
  • D. all are correct
Correct Answer: D

Rationale: The correct answer is D because nosocomial infections can be transmitted through various routes, including air droplets, fecal-oral mechanism, contact mechanism, and parenteral mechanism. Air droplets can carry infectious agents through the air, while contact with contaminated surfaces or individuals can spread infections. Fecal-oral transmission occurs through ingesting contaminated food or water. Parenteral transmission involves the introduction of pathogens directly into the bloodstream. Therefore, all the options listed in D are correct routes for transmission of nosocomial infections. Choices A, B, and C are incorrect because they do not encompass all possible routes of transmission for nosocomial infections.

The bacteria responsible for anthrax is:

  • A. Bacillus anthracis
  • B. Clostridium tetani
  • C. Mycobacterium tuberculosis
  • D. Streptococcus pneumoniae
Correct Answer: A

Rationale: The correct answer is A: Bacillus anthracis. This bacterium is known to cause anthrax, a serious infectious disease in humans and animals. Bacillus anthracis is a gram-positive, spore-forming bacterium that produces toxins leading to the characteristic symptoms of anthrax. Clostridium tetani causes tetanus, Mycobacterium tuberculosis causes tuberculosis, and Streptococcus pneumoniae causes pneumonia, none of which are related to anthrax. Therefore, based on the specific pathogen responsible for anthrax, Bacillus anthracis is the correct answer.

The human pinworm Enterobius vermicularis lives in the __________ of humans.

  • A. duodenum
  • B. ileum
  • C. transverse colon
  • D. rectum
Correct Answer: D

Rationale: The correct answer is D: rectum. Pinworms typically inhabit the rectum area in humans, where they lay their eggs. This is because the female pinworm migrates to the rectum at night to deposit her eggs near the anus. Other choices are incorrect because pinworms do not reside in the duodenum (A), ileum (B), or transverse colon (C) as their primary location is in the lower gastrointestinal tract near the anus.

Viruses cannot multiply in:

  • A. Artificial nutrient media
  • B. Living cells
  • C. Human embryonic cells
  • D. Bacteria
Correct Answer: A

Rationale: The correct answer is A: Artificial nutrient media. Viruses are obligate intracellular parasites, meaning they require living host cells to replicate. They cannot multiply in artificial nutrient media as they lack the cellular machinery necessary for viral replication. Living cells, including human embryonic cells and bacteria, provide the required cellular environment for viruses to replicate. Therefore, options B, C, and D are incorrect as they all contain living cells that can support viral multiplication.

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