Nokea
Cell mediated immunity has a leading role in:
- A. Infections with facultative and obligate intracellular pathogens
- B. Infections with extracellular pathogens
- C. Type 1 hypersensitivity reactions
- D. Toxin mediated infections
Correct Answer: A
Rationale: Cell-mediated immunity plays a crucial role in combating infections with intracellular pathogens by activating T cells to directly kill infected cells. Facultative and obligate intracellular pathogens, such as viruses and some bacteria, require cell-mediated immunity for effective clearance. Option A is correct due to the specificity of this immune response. Choices B, C, and D are incorrect as they are primarily associated with humoral immunity involving antibodies and not T cell responses against intracellular pathogens.
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Agents associated with human disease but generally not a serious health risk are classified in which of the following risk groups?
- A. RG1
- B. RG2
- C. RG3
- D. RG4
Correct Answer: B
Rationale: The correct answer is B: RG2. RG2 is appropriate for agents associated with human disease that pose a moderate health risk. These agents may cause disease of varying severity, but generally do not result in serious health consequences. Other choices are incorrect because: A: RG1 is for agents not associated with disease in healthy adults, C: RG3 is for agents associated with serious or lethal human disease, and D: RG4 is for agents that pose a high risk of life-threatening disease and for which there are no treatments.
Which of the following methods is the simplest heat-related method to sterilize metal?
- A. Incineration
- B. Autoclaving
- C. Direct flaming
- D. Indirect heating
Correct Answer: C
Rationale: The correct answer is C: Direct flaming. Direct flaming is the simplest heat-related method to sterilize metal because it involves passing the metal through a flame to kill microorganisms. The high temperature of the flame effectively destroys any bacteria or spores present on the metal surface. Incineration (A) is not practical for sterilizing metal as it involves burning at extremely high temperatures. Autoclaving (B) uses steam under pressure to sterilize, which is effective but more complex than direct flaming. Indirect heating (D) is not an effective method for sterilizing metal as it does not directly expose the metal to high temperatures required for sterilization.
A child suspected for tuberculosis underwent Mantoux test. 24 hours after allergen injection there appeared a swelling, hyperaemia and tenderness. What are the main components in the development of this reaction?
- A. Mononuclears, T-lymphocytes and lymphokines
- B. Granulocytes, T-lymphocytes and IgG
- C. Plasmatic cells, T-lymphocytes and lymphokines
- D. B-lymphocytes, IgM
Correct Answer: A
Rationale: The correct answer is A: Mononuclears, T-lymphocytes and lymphokines. In a Mantoux test reaction, mononuclear cells, mainly T-lymphocytes, are activated by the injected allergen. These T-lymphocytes release lymphokines, leading to the observed swelling, hyperaemia, and tenderness. Granulocytes and IgG (choice B) are not the primary players in this type of delayed hypersensitivity reaction. Plasmatic cells (choice C) are not involved in the initial stages of this reaction. B-lymphocytes and IgM (choice D) are not the key components in the Mantoux test reaction.
Nonchromosomal DNA molecules found in a bacterial cell are
- A. endospores.
- B. transposons.
- C. plasmids.
- D. prions.
Correct Answer: C
Rationale: The correct answer is C: plasmids. Plasmids are nonchromosomal DNA molecules commonly found in bacterial cells, providing additional genetic material for bacteria. They are not essential for bacterial survival but can confer advantages such as antibiotic resistance. Endospores (A) are dormant bacterial structures resistant to harsh conditions. Transposons (B) are mobile genetic elements that can move within a genome. Prions (D) are misfolded proteins causing neurodegenerative diseases, not DNA molecules.
A patient with pulmonary tuberculosis is prescribed the most effective antituberculous antibiotic. Name this drug:
- A. Furasolidone
- B. Bactrim (Co-trimoxazole)
- C. Streptocide
- D. Rifampicin
Correct Answer: D
Rationale: The correct answer is D: Rifampicin. Rifampicin is a first-line antibiotic for treating pulmonary tuberculosis due to its high efficacy against Mycobacterium tuberculosis. It works by inhibiting bacterial RNA synthesis. Furasolidone (A) is not commonly used for tuberculosis, Bactrim (B) is not a first-line drug for tuberculosis, and Streptocide (C) is not as effective as Rifampicin.