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What is the role of coagulase in bacteria like Staphylococcus aureus?
- A. It facilitates adhesion to surfaces
- B. It breaks down red blood cells
- C. It forms clots to evade immune responses
- D. It aids in antibiotic resistance
Correct Answer: C
Rationale: The correct answer is C because coagulase helps bacteria like Staphylococcus aureus to form clots, allowing them to evade the host immune response. This mechanism helps the bacteria to hide from the immune system and establish infection.
A. Adhesion to surfaces is usually facilitated by other factors like adhesins.
B. Breaking down red blood cells is not a function of coagulase.
D. Antibiotic resistance is typically mediated by other mechanisms like efflux pumps or enzymatic inactivation, not coagulase.
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Study of bacteriological sputum specimens stained by the Ziel-Neelsen method revealed some bright-red acid-resistant bacilli that were found in groups or singularly. When inoculated onto the nutrient media, the signs of their growth show up on the 10-15 day. These bacteria relate to the following family:
- A. Micobacterium tuberculosis
- B. Yersinia pseudotuberculosis
- C. Histoplasma dubrosii
- D. Klebsiella rhinoscleromatis
Correct Answer: A
Rationale: The correct answer is A: Mycobacterium tuberculosis.
1. Bright-red acid-resistant bacilli indicate the presence of mycolic acids in the cell wall, characteristic of Mycobacterium species.
2. Found in groups or singularly suggests the clumping nature of acid-fast bacilli.
3. Growth appearing after 10-15 days on nutrient media is consistent with the slow growth rate of Mycobacterium tuberculosis.
4. Yersinia pseudotuberculosis (B) and Klebsiella rhinoscleromatis (D) are not acid-fast bacilli and do not match the growth characteristics described.
5. Histoplasma dubrosii (C) is a fungus, not a bacterium, and does not exhibit acid-fast staining or the described growth pattern.
Which of the following bacteria is known for causing the disease known as leprosy?
- A. Mycobacterium leprae
- B. Clostridium perfringens
- C. Streptococcus pneumoniae
- D. Neisseria gonorrhoeae
Correct Answer: A
Rationale: Step-by-step rationale:
1. Mycobacterium leprae is the correct answer as it is the bacteria known to cause leprosy.
2. Clostridium perfringens is incorrect as it is associated with gas gangrene.
3. Streptococcus pneumoniae is incorrect as it is commonly linked to pneumonia and meningitis.
4. Neisseria gonorrhoeae is incorrect as it causes gonorrhea, a sexually transmitted infection.
In summary, Mycobacterium leprae is the only bacteria among the choices specifically known to cause leprosy, making it the correct answer.
The branch of pharmacology that addresses drug amounts at various sites in the body after drug administration is called:
- A. pharmacodynamics
- B. pharmacokinetics
- C. pharmacotherapeutics
- D. pharmacy
Correct Answer: B
Rationale: The correct answer is B: pharmacokinetics. Pharmacokinetics is the study of drug movement in the body, including absorption, distribution, metabolism, and excretion. It focuses on how the body processes a drug over time. Pharmacodynamics (A) is the study of the effects drugs have on the body. Pharmacotherapeutics (C) involves using drugs to treat diseases. Pharmacy (D) is the practice of preparing and dispensing medications. Pharmacokinetics specifically deals with drug concentrations at different body sites after administration, making it the most appropriate choice for this question.
Microscopic analysis of a smear stained by Ziehl-Neelsen method revealed bright red bacilli. What microorganism is being tested for?
- A. Mycobacterium tuberculosis
- B. Staphylococcus aureus
- C. Clostridium tetani
- D. Escherichia coli
Correct Answer: A
Rationale: The Ziehl-Neelsen stain is specific for acid-fast bacteria like Mycobacterium tuberculosis. The bright red bacilli seen in the smear indicate the presence of acid-fast organisms, which is characteristic of Mycobacterium tuberculosis. Staphylococcus aureus, Clostridium tetani, and Escherichia coli are not acid-fast bacteria and would not be stained red using the Ziehl-Neelsen method. Therefore, the correct answer is A: Mycobacterium tuberculosis.
The antigen receptors on the surface of B-lymphocytes are made by proteins:
- A. TRUE
- B. FALSE
- C. Both answers can be correct depending on the given situation
- D. None of the above
Correct Answer: A
Rationale: The correct answer is A: TRUE. B-lymphocyte antigen receptors are made by proteins called immunoglobulins. These proteins are essential for recognizing and binding to specific antigens. They play a crucial role in the immune response. Choice B is incorrect because B-lymphocyte antigen receptors are indeed made by proteins. Choice C is incorrect as well because in this case, the correct answer is that the receptors are made by proteins. Choice D is also incorrect as the receptors are made by proteins.