For family Togaviridae is true that
- A. they have helical type of symmetry
- B. they have non-segmented (-)dsRNA
- C. they have non-segmented (+)ssRNA
- D. they are non-enveloped viruses
Correct Answer: C
Rationale: Step 1: Togaviridae is a family of viruses known to have non-segmented (+)ssRNA as their genetic material.
Step 2: The positive sense RNA means that the viral RNA can be directly translated into proteins by host machinery.
Step 3: This RNA genome acts as mRNA, allowing for immediate translation of viral proteins.
Step 4: Therefore, choice C is correct as it accurately describes the genetic nature of Togaviridae.
Summary:
- Choice A is incorrect because Togaviridae viruses do not have helical symmetry.
- Choice B is incorrect because Togaviridae viruses do not have non-segmented (-)dsRNA.
- Choice D is incorrect because Togaviridae viruses are enveloped viruses.
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Poxviruses are DNA viruses that replicate in the cytoplasm.
- A. TRUE
- B. FALSE
- C. Partially
- D. Not Sure
Correct Answer: A
Rationale: Step 1: Poxviruses are indeed DNA viruses, confirmed by scientific research.
Step 2: Poxviruses replicate entirely in the cytoplasm, unlike most DNA viruses.
Step 3: Cytoplasmic replication is a unique characteristic of poxviruses.
Step 4: The replication process of poxviruses in the cytoplasm is well-documented.
Step 5: Therefore, option A (TRUE) is correct, as poxviruses replicate in the cytoplasm exclusively.
A patient has food poisoning. Laboratory analysis revealed a culture of anaerobic gram-positive spore-forming bacteria. What is the most likely kind of the isolated causative agent?
- A. C. perfringens
- B. Proteus vulgaris
- C. P. mirabilis
- D. Vibrio parahemolyticus
Correct Answer: A
Rationale: The correct answer is A: C. perfringens. This is because Clostridium perfringens is a gram-positive, anaerobic, spore-forming bacterium commonly associated with food poisoning. It produces toxins that cause gastrointestinal symptoms. Proteus vulgaris (B) and P. mirabilis (C) are gram-negative bacteria not typically associated with food poisoning. Vibrio parahemolyticus (D) is a gram-negative bacterium causing seafood-related gastroenteritis, not spore-forming or anaerobic.
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.
A 42-year-old woman has foamy purulent vaginal discharges. Microscopy revealed flagellated protozoa with an undulating membrane and pear-shaped structure. What organism was found?
- A. Trichomonas vaginalis
- B. Trypanosoma gambiense
- C. Leishmania donovani
- D. Lamblia intestinalis
Correct Answer: A
Rationale: The correct answer is A: Trichomonas vaginalis. Trichomonas vaginalis is a sexually transmitted protozoan parasite that causes trichomoniasis, characterized by foamy purulent vaginal discharges. Microscopy of vaginal discharge showing flagellated protozoa with an undulating membrane and pear-shaped structure is indicative of Trichomonas vaginalis. Trypanosoma gambiense causes African sleeping sickness and is transmitted by tsetse flies. Leishmania donovani causes visceral leishmaniasis transmitted by sandflies. Lamblia intestinalis causes giardiasis and is characterized by diarrhea and flatulence.
Which bacteria is responsible for causing leprosy?
- A. Streptococcus pyogenes
- B. Mycobacterium leprae
- C. Neisseria gonorrhoeae
- D. Escherichia coli
Correct Answer: B
Rationale: The correct answer is B: Mycobacterium leprae. This bacterium is responsible for causing leprosy, also known as Hansen's disease. Mycobacterium leprae specifically targets the skin, peripheral nerves, and mucosa of the upper respiratory tract. It is an acid-fast bacterium with a slow growth rate, making it difficult to culture in the laboratory. Streptococcus pyogenes (choice A) is responsible for various infections such as strep throat, Neisseria gonorrhoeae (choice C) causes gonorrhea, and Escherichia coli (choice D) is commonly found in the gut and can lead to various infections but not leprosy.