Nokea
Which statement is correct? Yersinia pestis is the causative agent of:
- A. Cholera
- B. AIDS
- C. Plague
- D. None of the above
Correct Answer: C
Rationale: The correct answer is C: Plague. Yersinia pestis is a bacterium that causes plague, a serious infectious disease transmitted through infected fleas or direct contact with infected animals. Yersinia pestis does not cause Cholera (choice A) or AIDS (choice B). Choice D, None of the above, is incorrect as Yersinia pestis is indeed the causative agent of plague.
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Which of the following scientists performed the first vaccination against smallpox?
- A. Pasteur
- B. Jenner
- C. Semmelweis
- D. Koch
Correct Answer: B
Rationale: The correct answer is B: Jenner. Edward Jenner performed the first vaccination against smallpox in 1796 by using cowpox virus to immunize individuals. He observed that milkmaids who had contracted cowpox did not get smallpox, leading to the development of the smallpox vaccine. Pasteur is known for germ theory, Semmelweis for handwashing in healthcare, and Koch for identifying the causative agents of diseases. However, none of them performed the first smallpox vaccination like Jenner.
Transcription of viral nucleic acid to mRNA is not needed in the case of:
- A. There is no correct answer
- B. Single strand DNA viruses
- C. Double strand DNA viruses
- D. Positive strand RNA viruses
Correct Answer: D
Rationale: The correct answer is D: Positive strand RNA viruses. These viruses have RNA genomes that can be directly translated by host ribosomes without the need for transcription. In contrast, single-strand DNA and double-strand DNA viruses require transcription to generate mRNA for translation. Choice A is incorrect as there is a correct answer. Choice B and C are incorrect because both single-strand DNA and double-strand DNA viruses require transcription for mRNA synthesis.
Which type of bacteria can survive in both aerobic and anaerobic environments?
- A. Obligate aerobes
- B. Facultative anaerobes
- C. Obligate anaerobes
- D. Microaerophiles
Correct Answer: B
Rationale: Certainly! The correct answer is B: Facultative anaerobes. Facultative anaerobes can survive in both aerobic and anaerobic environments due to their ability to switch between utilizing oxygen for respiration in aerobic conditions and utilizing fermentation or anaerobic respiration in anaerobic conditions. This flexibility allows them to thrive in diverse environments.
Explanation for incorrect choices:
A: Obligate aerobes require oxygen for respiration and cannot survive in anaerobic environments.
C: Obligate anaerobes can only survive in the absence of oxygen and would not thrive in aerobic conditions.
D: Microaerophiles require low levels of oxygen to grow and are not as versatile in adapting to varying oxygen levels compared to facultative anaerobes.
A patient with pneumonia had sputum cultured, revealing Gram-negative diplococci. The bacteria were oxidase-positive and fermentative. What is the most likely causative agent?
- A. Neisseria meningitidis
- B. Neisseria gonorrhoeae
- C. Moraxella catarrhalis
- D. Haemophilus influenzae
Correct Answer: A
Rationale: The correct answer is A: Neisseria meningitidis. This is because Neisseria meningitidis is a Gram-negative diplococcus that is oxidase-positive and fermentative. Neisseria gonorrhoeae is also a Gram-negative diplococcus, but it is not fermentative. Moraxella catarrhalis is oxidase-positive but not fermentative. Haemophilus influenzae is Gram-negative but is not a diplococcus, and it is not fermentative. Therefore, based on the characteristics provided in the question, Neisseria meningitidis is the most likely causative agent.
A patient with pulmonary tuberculosis is prescribed the most effective antituberculosis antibiotic. Name this drug:
- A. Tetracycline
- B. Furasolidone
- C. Rifampicin
- D. Bactrim (Co-trimoxazole)
Correct Answer: C
Rationale: Rifampicin is the correct answer because it is a first-line antibiotic for treating pulmonary tuberculosis. It has excellent bactericidal activity and penetrates well into lung tissues where the infection is located. Rifampicin is also known for preventing the development of resistance. Tetracycline (A) and Furasolidone (B) are not commonly used for tuberculosis treatment. Bactrim (D) is a combination of sulfamethoxazole and trimethoprim, not effective for tuberculosis treatment.