Which of the following bacteria is responsible for causing the disease known as tuberculosis?
- A. Mycobacterium tuberculosis
- B. Neisseria meningitidis
- C. Salmonella enterica
- D. Streptococcus pneumoniae
Correct Answer: A
Rationale: The correct answer is A: Mycobacterium tuberculosis. This bacteria is responsible for causing tuberculosis because it is the specific pathogen known to infect the lungs and other parts of the body, leading to the disease. Mycobacterium tuberculosis has unique cell wall components that allow it to evade the immune system and survive in the host.
Neisseria meningitidis (B) causes meningitis, not tuberculosis. Salmonella enterica (C) causes food poisoning, not tuberculosis. Streptococcus pneumoniae (D) causes pneumonia, not tuberculosis. Therefore, the correct answer is A based on the specific characteristics and pathogenicity of Mycobacterium tuberculosis.
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Which of the following statements for genus Klebsiella is correct?
- A. They have real capsule and are non-motile
- B. They are obligatory anaerobic
- C. They form spores only under aerobic conditions
- D. None of the above
Correct Answer: A
Rationale: The correct answer is A because Klebsiella species have a real capsule, which is a distinguishing feature used for their identification. This capsule helps them evade the host immune response. Additionally, Klebsiella species are non-motile, meaning they do not possess flagella for movement. Choices B and C are incorrect because Klebsiella species are facultative anaerobes and do not form spores under any conditions. Choice D is also incorrect as option A is the correct statement for genus Klebsiella.
Agglutination reaction is one of the following:
- A. Western blot
- B. ELISA
- C. Reaction type GRUBER
- D. Ascoli ring test
Correct Answer: C
Rationale: The correct answer is C: Reaction type GRUBER. Agglutination reaction in GRUBER involves the clumping of particles due to specific antibodies binding to antigens on the surface. This reaction is commonly used in blood typing and serology tests.
A: Western blot is a technique used to detect specific proteins in a sample, not related to agglutination.
B: ELISA is an enzyme-linked immunosorbent assay used to detect antibodies or antigens, not based on agglutination.
D: Ascoli ring test is a method to detect the presence of DNA in a sample, not related to agglutination.
A toxic, odorless gas often used as a sterilizing agent in hospitals and dental officials is
- A. ethylene oxide.
- B. carbon dioxide.
- C. carbon monoxide.
- D. propane.
Correct Answer: A
Rationale: The correct answer is A: ethylene oxide. Ethylene oxide is a toxic, odorless gas commonly used as a sterilizing agent in healthcare settings due to its ability to effectively kill bacteria, viruses, and fungi. It is a highly reactive compound that can penetrate porous materials, making it an ideal choice for sterilization purposes.
Incorrect choices:
B: Carbon dioxide is not used as a sterilizing agent and is not toxic.
C: Carbon monoxide is not commonly used for sterilization and has a distinct odor.
D: Propane is not used for sterilization in healthcare settings and is not odorless.
Which of the following viruses belong to family Arenaviridae
- A. Lassa virus
- B. Crimean-Congo hemorrhagic fever virus
- C. Rabies virus
- D. Epstein-Bar virus
Correct Answer: A
Rationale: The correct answer is A: Lassa virus. The rationale is as follows:
1. Lassa virus is a member of the Arenaviridae family, known for causing Lassa fever.
2. Arenaviridae family includes viruses with a segmented genome and are transmitted through rodents.
3. Crimean-Congo hemorrhagic fever virus (Choice B) belongs to the Bunyaviridae family, not Arenaviridae.
4. Rabies virus (Choice C) belongs to the Rhabdoviridae family, not Arenaviridae.
5. Epstein-Barr virus (Choice D) belongs to the Herpesviridae family, not Arenaviridae.
In summary, Lassa virus is the correct choice as it aligns with the characteristics of the Arenaviridae family, while the other choices belong to different virus families.
The classic causative agent of croupous pneumonia is:
- A. Chlamydia pneumoniae
- B. Streptococcus pneumoniae
- C. Mycoplasmas pneumoniae
- D. Staphylococcus aureus
Correct Answer: B
Rationale: The correct answer is B, Streptococcus pneumoniae. This bacterium is the classic causative agent of croupous pneumonia due to its ability to infect the lungs and cause inflammation. Streptococcus pneumoniae is a common pathogen known for causing pneumonia in both adults and children. It is characterized by the presence of a capsule that helps it evade the host immune system.
Choice A, Chlamydia pneumoniae, is not the correct answer as it is more commonly associated with atypical pneumonia. Choice C, Mycoplasma pneumoniae, is also associated with atypical pneumonia and not croupous pneumonia. Choice D, Staphylococcus aureus, can cause pneumonia, but it is not the classic causative agent of croupous pneumonia.