Nokea
The causative agent of the pertussis (also known as whooping cough) morphologically appears as:
- A. Gram positive bacillus
- B. Gram negative coccobacillus
- C. Long Gram-negative rod shaped bacterium
- D. None of the above
Correct Answer: B
Rationale: The correct answer is B: Gram negative coccobacillus. Bordetella pertussis, the causative agent of pertussis, is a gram-negative coccobacillus. This is because it is a small, rod-shaped bacterium that appears both as a bacillus (rod-shaped) and a coccus (spherical) shape. It does not retain the crystal violet stain in the Gram staining process, indicating its negative gram nature. Choice A is incorrect because pertussis is not a gram-positive bacillus. Choice C is incorrect because pertussis is not a long gram-negative rod-shaped bacterium. Choice D is incorrect as the other options do not accurately describe the morphology of Bordetella pertussis.
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Which of the following bacteria is responsible for causing the plague?
- A. Yersinia pestis
- B. Clostridium difficile
- C. Neisseria gonorrhoeae
- D. Pseudomonas aeruginosa
Correct Answer: A
Rationale: The correct answer is A: Yersinia pestis. Y. pestis is responsible for causing the plague, a severe infectious disease. This bacterium is transmitted via fleas from rodents to humans. It causes bubonic, septicemic, and pneumonic plague. Clostridium difficile causes gastrointestinal infections, Neisseria gonorrhoeae causes gonorrhea, and Pseudomonas aeruginosa can cause various infections but not the plague.
The causative agent of syphilis is:
- A. Borrelia burgdorferi
- B. Treponema pallidum
- C. Leptospira interrogans
- D. Rickettsia rickettsii
Correct Answer: B
Rationale: The correct answer is B: Treponema pallidum.
1. Treponema pallidum is a spirochete bacterium known to cause syphilis.
2. Borrelia burgdorferi causes Lyme disease, not syphilis.
3. Leptospira interrogans causes leptospirosis, not syphilis.
4. Rickettsia rickettsii causes Rocky Mountain spotted fever, not syphilis.
Therefore, Treponema pallidum is the causative agent of syphilis, making it the correct answer.
What is the primary function of bacterial ribosomes?
- A. Synthesize proteins
- B. Generate ATP
- C. Produce DNA
- D. Synthesize lipids
Correct Answer: A
Rationale: The correct answer is A: Synthesize proteins. Bacterial ribosomes are responsible for translating mRNA into proteins through a process called translation. Ribosomes do not generate ATP (choice B), produce DNA (choice C), or synthesize lipids (choice D). These processes are carried out by other cellular components such as mitochondria for ATP production, DNA polymerase for DNA replication, and enzymes for lipid synthesis. The primary function of bacterial ribosomes is protein synthesis, making choice A the correct answer.
The normal microflora is related to the defense in pathogens in
- A. circulatory system
- B. hepatobiliary tract
- C. skin and mucus
- D. CNS
Correct Answer: C
Rationale: The normal microflora plays a crucial role in defending against pathogens in the skin and mucus. This is because the skin and mucus act as physical barriers and the normal microflora outcompetes potential pathogens, preventing their colonization. In contrast, the circulatory system (A), hepatobiliary tract (B), and CNS (D) are not typically colonized by normal microflora, so they do not directly contribute to defense against pathogens in those areas.
Which one of the methods is used to identify cytoplasmic inclusions?
- A. Neisser staining
- B. Clett staining
- C. Ziehl-Nielsen staining
- D. Gram staining
Correct Answer: A
Rationale: The correct answer is A: Neisser staining. This method is specifically used to identify cytoplasmic inclusions by staining them with a specific dye that highlights these structures. Neisser staining is designed to selectively target and visualize cytoplasmic inclusions, making it the most appropriate choice for this purpose.
Option B: Clett staining, Option C: Ziehl-Nielsen staining, and Option D: Gram staining are not typically used for identifying cytoplasmic inclusions. Clett staining is not a commonly known staining method for this purpose. Ziehl-Nielsen staining is primarily used to detect acid-fast bacteria like Mycobacterium tuberculosis. Gram staining is used to differentiate bacteria into Gram-positive and Gram-negative based on cell wall characteristics. Therefore, these options are not suitable for identifying cytoplasmic inclusions.