Free Microbiology Test Bank Questions PDF

Free Microbiology Test Bank Questions PDF Related

Review Free Microbiology Test Bank Questions PDF related questions and content

A patient working at a pig farm complains about paroxysmal abdominal pain, liquid feces with admixtures of mucus and blood, headache, weakness, fever. Examination of large intestine revealed ulcers from 1 mm up to several cm large, feces contained oval unicellular organisms with cilia. What disease should be suspected?

  • A. Balantidiasis
  • B. Amebiasis
  • C. Toxoplasmosis
  • D. Lambliasis
Correct Answer: A

Rationale: Rationale: The symptoms described are consistent with Balantidiasis, caused by the parasite Balantidium coli. The presence of ciliated oval organisms in the feces is characteristic of this disease. Ulcers in the large intestine are common in Balantidiasis due to tissue invasion by the parasite. Headache, fever, and abdominal pain are typical symptoms. Other choices can be ruled out: B) Amebiasis presents with similar symptoms but usually involves the liver. C) Toxoplasmosis typically presents with lymphadenopathy and flu-like symptoms. D) Lambliasis usually causes watery diarrhea without blood or mucus. Therefore, the correct answer is A: Balantidiasis.

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Which type of bacteria can survive in extreme salty environments?

  • A. Psychrophiles
  • B. Halophiles
  • C. Thermophiles
  • D. Mesophiles
Correct Answer: B

Rationale: The correct answer is B: Halophiles. Halophiles are bacteria that can survive in extreme salty environments. They have adapted to thrive in high salt concentrations. Psychrophiles (A) thrive in cold temperatures, Thermophiles (C) thrive in high temperatures, and Mesophiles (D) thrive in moderate temperatures. Therefore, they are not adapted to survive in extreme salty environments like Halophiles.

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.

Antibiotics are distributed into following groups:

  • A. Blockaders of protein synthesis
  • B. Blockaders of cell wall synthesis
  • C. Alternators of bacterial cytoplasm
  • D. Nothing from above
Correct Answer: A

Rationale: The correct answer is A: Blockaders of protein synthesis because antibiotics in this group target bacterial ribosomes, preventing protein synthesis. This disrupts bacterial growth and replication. Choice B is incorrect as cell wall synthesis inhibitors target a different bacterial component. Choice C is incorrect as antibiotics do not alter bacterial cytoplasm. Choice D is incorrect as antibiotics do fall into different categories based on their mechanism of action.

The term “zone of inhibition†is used in which of the following procedures?

  • A. Use-dilution test
  • B. Growth inhibition test
  • C. Disk-diffusion test
  • D. Multiple inhibition test
Correct Answer: C

Rationale: The correct answer is C: Disk-diffusion test. In the disk-diffusion test, the zone of inhibition refers to the area around an antimicrobial disk where bacterial growth is inhibited. This test is used to determine the susceptibility of bacteria to specific antibiotics. The other choices, such as A: Use-dilution test, B: Growth inhibition test, and D: Multiple inhibition test, do not specifically involve measuring the zone of inhibition and are not commonly used methods for testing antibiotic susceptibility.

Microscopic examination of dental plaque revealed unicellular organisms with two layers in their cytoplasm and wide pseudopodia. What is the likely causative agent?

  • A. Entamoeba gingivalis
  • B. Entamoeba histolytica
  • C. Trichomonas tenax
  • D. Lamblia intestinalis
Correct Answer: A

Rationale: Rationale:
1. Unicellular organisms with two layers in cytoplasm = Entamoeba gingivalis.
2. Wide pseudopodia = characteristic of Entamoeba genus.
3. Entamoeba histolytica causes amoebic dysentery, not dental plaque.
4. Trichomonas tenax causes periodontal disease, not dental plaque.
5. Lamblia intestinalis causes giardiasis, not related to dental plaque.

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