Nokea
Which of the following stains is the most widely used differential stain in hematology laboratories?
- A. Carbolfuchsin stain
- B. Wright’s stain
- C. Ziehl-Neelson stain
- D. Kinyoun stain
Correct Answer: D
Rationale: The correct answer is D: Kinyoun stain. This stain is the most widely used differential stain in hematology labs because it is specifically designed for acid-fast bacteria like Mycobacterium tuberculosis. It differentiates these bacteria from others based on their cell wall composition. Carbolfuchsin stain (A) is used for acid-fast bacteria in microbiology. Wright's stain (B) is used for blood cell morphology. Ziehl-Neelsen stain (C) is also used for acid-fast bacteria but is less commonly used compared to Kinyoun stain in hematology labs.
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Fires from flammable metals require type __________ fire extinguishers.
- A. A
- B. B
- C. C
- D. D
Correct Answer: D
Rationale: The correct answer is D because fires from flammable metals require specialized Class D fire extinguishers designed to extinguish these unique types of fires. Class A, B, and C fire extinguishers are not suitable for flammable metal fires as they are designed for different types of materials and fire classes. Class A extinguishers are for ordinary combustibles, Class B for flammable liquids, and Class C for electrical fires. Therefore, Class D fire extinguishers are specifically designed for flammable metal fires, making them the correct choice for this scenario.
It is planned to use the territory of an old cattle burial ground (which is not used for more than 50 years) for building houses. But ground analysis revealed presence of the pathogen of the very dangerous illness. Which of the indicated microorgonisms is likely to remain in the ground for such a long time?
- A. Mycobacterium bovis
- B. Brucella abortus
- C. Bacillus anthracis
- D. Francisella tularensis
Correct Answer: C
Rationale: Rationale:
1. Bacillus anthracis is a spore-forming bacterium that can survive for decades in the soil.
2. The spores are resistant to harsh conditions and can remain dormant for long periods.
3. This resilience allows Bacillus anthracis to persist in the old cattle burial ground for over 50 years.
4. Mycobacterium bovis, Brucella abortus, and Francisella tularensis are not known for long-term survival in soil.
Summary:
- Mycobacterium bovis, Brucella abortus, and Francisella tularensis do not have the spore-forming ability.
- Mycobacterium bovis causes tuberculosis in cattle.
- Brucella abortus causes brucellosis in cattle.
- Francisella tularensis causes tularemia in animals and humans.
Gram-negative bacteria have a cell wall that:
- A. contains teichoic acid
- B. is thicker than that of Gram-positive bacteria
- C. contains lipopolysaccharides
- D. is composed entirely of peptidoglycan
Correct Answer: C
Rationale: The correct answer is C, as Gram-negative bacteria have a cell wall containing lipopolysaccharides. This outer membrane structure is unique to Gram-negative bacteria and plays a critical role in pathogenicity and immune response. Teichoic acid (choice A) is found in Gram-positive bacteria. The cell wall of Gram-negative bacteria is thinner than that of Gram-positive bacteria (choice B). The cell wall of Gram-negative bacteria is not composed entirely of peptidoglycan (choice D), as it also contains other components like lipopolysaccharides.
What type of bacteria is responsible for the formation of acid in the stomach?
- A. Staphylococcus aureus
- B. Helicobacter pylori
- C. Bacillus cereus
- D. Clostridium botulinum
Correct Answer: B
Rationale: The correct answer is B: Helicobacter pylori. This bacterium is responsible for stomach acid formation by producing an enzyme called urease, which converts urea into ammonia and carbon dioxide, leading to an increase in stomach pH. Staphylococcus aureus (A) does not cause stomach acid formation. Bacillus cereus (C) and Clostridium botulinum (D) are not involved in stomach acid processes.
Which scientist performed the first successful vaccination against smallpox?
- A. Pasteur
- B. Jenner
- C. Semmelweis
- D. Koch
Correct Answer: B
Rationale: The correct answer is B: Jenner. Edward Jenner is credited with performing the first successful vaccination against smallpox in 1796. He used cowpox virus to inoculate individuals, leading to immunity against smallpox. Jenner's experiment laid the foundation for modern vaccination. Pasteur (A) is known for developing the germ theory of disease. Semmelweis (C) advocated for handwashing to prevent infections. Koch (D) identified the causative agents of several diseases but did not develop the smallpox vaccine.