Nokea
What is the primary mode of transmission for tetanus?
- A. Ingestion of contaminated food
- B. Inhalation of droplets
- C. Contaminated wounds
- D. Direct physical contact
Correct Answer: C
Rationale: The correct answer is C: Contaminated wounds. Tetanus is caused by the bacterium Clostridium tetani, which enters the body through breaks in the skin such as wounds or cuts. The bacteria produce a toxin that affects the nervous system, leading to muscle stiffness and spasms. Ingestion of contaminated food (choice A) is not a mode of transmission for tetanus. Inhalation of droplets (choice B) is more relevant for respiratory infections. Direct physical contact (choice D) is not the primary mode of transmission for tetanus as the bacteria need a portal of entry such as a wound to cause infection.
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Rod-shaped bacteria, some of which are endospore forming, are referred to as:
- A. cocci
- B. bacilli
- C. spirals
- D. vibrios
Correct Answer: B
Rationale: The correct answer is B. Bacilli are rod-shaped bacteria, some of which are endospore forming. Cocci are spherical, spirals are spiral-shaped, and vibrios are curved rod-shaped bacteria. Bacilli specifically refer to rod-shaped bacteria, making it the correct answer in this context.
Which of the following statements about in vitro cultivation of viruses is true?
- A. Viral cultivation under laboratory conditions is impossible
- B. Viruses are cultured on hen embryos, cell cultures and experimental animals
- C. Viruses are cultivated on special nutrient media
- D. Viruses are cultured only in human embryonic cell cultures
Correct Answer: B
Rationale: The correct answer is B because viruses can indeed be cultured on hen embryos, cell cultures, and experimental animals in vitro. This method allows for the replication and study of viruses outside the host organism. Option A is incorrect as viral cultivation is possible in laboratory settings. Option C is incorrect because while viruses can be grown on nutrient media, it is not the only method. Option D is incorrect as viruses can be cultured in various types of cell cultures, not just human embryonic ones.
A patient of surgical department complains about pain in the small of her back and in the lower part of her belly; painful and frequent urination. Bacteriological examination of urine revealed gram-negative oxidase-positive rod-like bacteria forming greenish mucoid colonies with specific smell. What causative agent can it be?
- A. Pseudomonas aeruginosa
- B. Proteus mirabilis
- C. E.coli
- D. Str.pyogenes
Correct Answer: B
Rationale: The correct answer is B: Proteus mirabilis. This bacterium is known to cause urinary tract infections (UTIs) and matches the description given in the question. Proteus mirabilis is a gram-negative rod-like bacterium that forms greenish mucoid colonies with a specific smell due to its production of urease enzyme. This enzyme leads to the formation of struvite crystals, which can cause painful and frequent urination. Pseudomonas aeruginosa (A) is not typically associated with UTIs. E.coli (C) is the most common cause of UTIs but does not match the specific description provided. Str.pyogenes (D) is a gram-positive bacterium and is not typically associated with UTIs.
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?
- A. RNA major
- B. -RNA
- C. (+RNA)
- D. RNA minor
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.
Which of the following is characteristic of obligate anaerobes?
- A. They require oxygen to survive
- B. They can survive in the presence or absence of oxygen
- C. They cannot tolerate oxygen
- D. They prefer low levels of oxygen
Correct Answer: C
Rationale: The correct answer is C: Obligate anaerobes cannot tolerate oxygen. They lack the enzymes needed to detoxify reactive oxygen species generated in the presence of oxygen. This makes them unable to survive in oxygen-rich environments. Choice A is incorrect because obligate anaerobes do not require oxygen to survive. Choice B is incorrect because obligate anaerobes specifically require the absence of oxygen. Choice D is incorrect because obligate anaerobes cannot even tolerate low levels of oxygen.