microbiology an evolving science test bank

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The process of bacterial conjugation involves:

  • A. DNA transfer via bacteriophage
  • B. Uptake of naked DNA from the environment
  • C. Direct transfer of DNA between two bacterial cells
  • D. Binary fission
Correct Answer: C

Rationale: The correct answer is C: Direct transfer of DNA between two bacterial cells. In bacterial conjugation, genetic material is transferred directly from one bacterial cell to another through a conjugative pilus. This process involves physical contact between the cells, followed by the transfer of plasmid DNA or chromosomal DNA. This mechanism allows for the exchange of genetic information between bacteria, leading to genetic diversity.

Explanation of why other choices are incorrect:
A: DNA transfer via bacteriophage - Bacteriophage is a virus that infects bacteria and transfers its genetic material, but this is not the mechanism involved in bacterial conjugation.
B: Uptake of naked DNA from the environment - This process is known as transformation, where bacteria take up free DNA from the environment, but it is not specific to bacterial conjugation.
D: Binary fission - Binary fission is a form of asexual reproduction in bacteria where a single cell divides into two identical cells, and it is not related to the process

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Which one is an example of an immunomodulator:

  • A. Rifampin
  • B. Gamma Interferon
  • C. Hexacima
  • D. Pentaxim
Correct Answer: B

Rationale: Step-by-step rationale for why B (Gamma Interferon) is the correct answer:
1. Gamma Interferon is a type of immunomodulator that helps regulate the immune response.
2. It activates macrophages and enhances the immune system's ability to fight infections.
3. Rifampin is an antibiotic, not an immunomodulator.
4. Hexacima and Pentaxim are combination vaccines, not immunomodulators.
In summary, Gamma Interferon is the correct answer as it directly influences the immune response, while the other choices are not immunomodulators.

The cleanup of various industrial wastes by living organisms is referred to as __________.

  • A. biomining
  • B. biosynthesis
  • C. bioremediation
  • D. bioengineering
Correct Answer: C

Rationale: The correct answer is C: bioremediation. Bioremediation is the process of using living organisms to clean up environmental pollution, including industrial wastes. This method utilizes microorganisms, plants, or fungi to break down or neutralize pollutants. Biomining (A) is the process of extracting valuable metals from ores using biological organisms. Biosynthesis (B) refers to the production of complex molecules by living organisms. Bioengineering (D) involves the application of engineering principles to biological systems, not specifically related to cleaning up industrial wastes. Therefore, the most appropriate term for the cleanup of industrial wastes by living organisms is bioremediation.

Microscopy of stained (Ziehl-Neelsen staining) smears taken from the sputum of a patient with chronic pulmonary disease revealed red bacilli. What property of tuberculous bacillus was shown up?

  • A. Acid resistance
  • B. Alkali resistance
  • C. Alcohol resistance
  • D. Capsule formation
Correct Answer: A

Rationale: The correct answer is A: Acid resistance. Tuberculous bacilli are acid-fast bacilli, meaning they resist decolorization by acid-alcohol after staining with Ziehl-Neelsen stain. This property is due to the high lipid content in the cell wall of Mycobacterium tuberculosis. Alkali resistance (B) and alcohol resistance (C) are not specific properties of tuberculous bacilli. Capsule formation (D) is a characteristic of some bacteria but is not a defining feature of tuberculous bacilli.

Agglutination reaction is one of the following:

  • A. Western blot
  • B. ELISA
  • C. Reaction type GRUBER
  • D. Ascoli ring test
Correct Answer: C

Rationale: The correct answer is C: Reaction type GRUBER. Agglutination reaction in GRUBER involves the clumping of particles due to specific antibodies binding to antigens on the surface. This reaction is commonly used in blood typing and serology tests.

A: Western blot is a technique used to detect specific proteins in a sample, not related to agglutination.
B: ELISA is an enzyme-linked immunosorbent assay used to detect antibodies or antigens, not based on agglutination.
D: Ascoli ring test is a method to detect the presence of DNA in a sample, not related to agglutination.

Following treatment with a highly efficient anti-tuberculosis drug a 48-yearold female developed optic nerve neuritis, memory impairment, cramps. Which of these anti-TB drugs had the patient taken?

  • A. Isoniazid
  • B. PASA
  • C. Rifampicin
  • D. Ethambutol
Correct Answer: D

Rationale: Step 1: The symptoms of optic nerve neuritis, memory impairment, and cramps are indicative of ethambutol toxicity.
Step 2: Ethambutol is known to cause optic nerve toxicity leading to neuritis, as well as CNS toxicity causing memory impairment.
Step 3: Ethambutol can also lead to peripheral neuropathy manifesting as cramps.
Step 4: Isoniazid is associated with peripheral neuropathy and hepatotoxicity but not with optic nerve neuritis or memory impairment.
Step 5: PASA is not commonly used for tuberculosis treatment and does not cause the described symptoms.
Step 6: Rifampicin is known for hepatotoxicity and flu-like symptoms, but not specifically for optic nerve neuritis, memory impairment, or cramps.
Summary: Ethambutol is the correct answer due to its known side effects of optic nerve toxicity, CNS toxicity, and peripheral neuropathy, which align with the presented symptoms. Ison

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