Nokea
For which family the following morphological features are typical: filamentous spiral nucleocapsid, linear unsegmented single strand (-) RNA and lipid bilayer membrane of cellular origin:
- A. Picornaviridae
- B. Filoviridae
- C. Orthomyxoviridae
- D. Togaviridae
Correct Answer: B
Rationale: Step-by-step rationale:
1. Filamentous spiral nucleocapsid is characteristic of Filoviridae, such as Ebola virus.
2. Linear unsegmented single strand (-) RNA is a key feature of Filoviridae genomes.
3. The lipid bilayer membrane of cellular origin is found in Filoviridae viruses.
4. Therefore, the correct answer is B (Filoviridae) due to the alignment of all three morphological features.
Summary:
- A (Picornaviridae): Has an icosahedral capsid, not filamentous spiral.
- C (Orthomyxoviridae): Has a segmented genome, not linear unsegmented.
- D (Togaviridae): Has a spherical capsid, not filamentous spiral.
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Native microscopic slides are good for observation of:
- A. Motility
- B. Division
- C. Presence of capsules
- D. None of the above
Correct Answer: A
Rationale: The correct answer is A: Motility. Native microscopic slides are ideal for observing motility because they allow for the observation of living microorganisms in their natural state. By observing the movement of microorganisms on a native slide, one can assess their motility characteristics accurately.
Choice B (Division) is incorrect because native slides may not provide the ideal conditions for observing cell division, as it may be difficult to capture the exact moment of division in a live organism.
Choice C (Presence of capsules) is also incorrect because observing capsules usually requires specific staining techniques that may not be suitable for native slides.
Choice D (None of the above) is incorrect as native slides are indeed beneficial for observing motility.
The most important fungi that cause diseases of the skin, hair, and nails are called:
- A. Plasmodium
- B. sporozoites
- C. dermatophytes
- D. nematodes
Correct Answer: C
Rationale: Correct Answer: C: dermatophytes
Rationale:
1. Dermatophytes are fungi that specifically infect the skin, hair, and nails.
2. They are the most common fungi causing such infections in humans.
3. Plasmodium and sporozoites are parasites causing malaria, not skin diseases.
4. Nematodes are a type of roundworm and do not typically cause skin, hair, or nail infections.
In summary, dermatophytes are the correct answer because they are specialized fungi that commonly cause skin, hair, and nail diseases, distinguishing them from the other choices.
The sample used to proving epidemic meningitis is:
- A. CSF transported at 37°C (CSF sample, blood, nasopharyngeal secretion)
- B. Feces
- C. CSF transported at +4°C
- D. None of the above
Correct Answer: A
Rationale: The correct answer is A because CSF (Cerebrospinal fluid) is the sample used for proving epidemic meningitis. It should be transported at 37°C to maintain its integrity. Blood and nasopharyngeal secretions are not typically used for diagnosing meningitis. Choice B, feces, is unrelated to the diagnosis of meningitis. Choice C, CSF transported at +4°C, is incorrect as it should be transported at 37°C to prevent degradation of the sample. Therefore, A is the correct choice for proving epidemic meningitis due to the specificity of the sample and the proper transport conditions.
Which bacteria are capable of surviving in anoxic (oxygen-free) conditions?
- A. Obligate anaerobes
- B. Facultative anaerobes
- C. Obligate aerobes
- D. Microaerophiles
Correct Answer: A
Rationale: The correct answer is A: Obligate anaerobes. These bacteria can only survive in the absence of oxygen as they lack the enzymes needed for aerobic respiration. They typically use fermentation or anaerobic respiration for energy production.
Incorrect choices:
B: Facultative anaerobes can switch between aerobic and anaerobic metabolism based on oxygen availability.
C: Obligate aerobes require oxygen for survival and cannot survive in anoxic conditions.
D: Microaerophiles require low levels of oxygen for growth and are not capable of surviving in completely anoxic conditions.
The most important virulence factor of Bordetella pertussis is:
- A. the flagellum
- B. pertussis toxin
- C. P fimbriae
- D. mannose-resistant adhesins
Correct Answer: B
Rationale: The correct answer is B: pertussis toxin. This toxin is the most important virulence factor of Bordetella pertussis because it plays a key role in causing the characteristic symptoms of whooping cough. Pertussis toxin interferes with the host's immune response, leading to inflammation and tissue damage in the respiratory tract. The other choices (A: the flagellum, C: P fimbriae, D: mannose-resistant adhesins) are important for bacterial attachment and colonization, but they do not directly contribute to the severity of the disease like pertussis toxin does.