Nokea
Which of the following statements is NOT true about influenza viruses?
- A. they are spherical viruses coated with a lipoprotein coat
- B. hemagglutinin and neuraminidase of flu viruses are antigenically variable
- C. the susceptibility of the population to influenza viruses is high
- D. there is no specific prophylaxis available
Correct Answer: D
Rationale: The correct answer is D because there is specific prophylaxis available for influenza, such as the flu vaccine. Choice A is incorrect as influenza viruses are not spherical, they are typically pleomorphic. Choice B is incorrect because hemagglutinin and neuraminidase are indeed antigenically variable, contributing to the need for annual flu vaccines. Choice C is incorrect as the susceptibility of the population to influenza viruses can vary depending on factors such as immunity and vaccination status.
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The most important virulence factor of Neisseria meningitidis is:
- A. Exotoxin
- B. Polysaccharide capsule
- C. Beta-lactamase
- D. Pyrogenic toxin
Correct Answer: B
Rationale: The correct answer is B: Polysaccharide capsule. The capsule of Neisseria meningitidis is crucial for its virulence as it helps the bacteria evade the host immune system by inhibiting phagocytosis. This allows the bacteria to survive and multiply in the host, leading to invasive infections. Exotoxins, beta-lactamase, and pyrogenic toxins are not the main virulence factors of Neisseria meningitidis and do not play as significant a role in its pathogenicity as the polysaccharide capsule.
For measles virus is true that:
- A. There is no outer membrane
- B. Contains singles-stranded RNA with negative polarity
- C. Belongs to family Togaviridae
- D. Cannot be grown on cell cultures
Correct Answer: B
Rationale: The correct answer is B: Contains single-stranded RNA with negative polarity. Measles virus is an enveloped virus with a single-stranded RNA genome that is negative-sense. This means it must first be transcribed into positive-sense RNA before it can be translated. Choice A is incorrect as the measles virus does have an outer envelope. Choice C is incorrect as measles virus belongs to the family Paramyxoviridae, not Togaviridae. Choice D is incorrect as measles virus can be grown on cell cultures, specifically on Vero cells.
From a medicinal herb a certain phytopathogenic microorganism was secured. In the nutrient medium it forms "fried egg"colonies. What is the most likely agent?
- A. Mycoplasma B.Yeasts C.Actinomycetes D.Nocardia E.Pseudomonas Legionella
Correct Answer: C
Rationale: Step 1: "Fried egg" colonies typically refer to colonies with a raised center and flattened periphery, resembling the appearance of a fried egg.
Step 2: Actinomycetes are filamentous bacteria known to form "fried egg" colonies in nutrient medium.
Step 3: Actinomycetes are commonly found in soil and are known to be phytopathogenic microorganisms.
Step 4: Actinomycetes produce secondary metabolites with medicinal properties, making them a likely agent from a medicinal herb.
Overall, the correct answer is C (Actinomycetes) as they fit the description provided in the question and are commonly associated with the given scenario. The other choices are incorrect as they do not exhibit the specific characteristics mentioned in the question or are not typically associated with forming "fried egg" colonies in nutrient medium.
Which of the following microorganisms can be cultured only in the footpads of mice or a species of armadillo?
- A. Mycobacterium tuberculosis
- B. Mycobacterium leprae
- C. Neisseria gonorrhoeae
- D. Mycoplasma
Correct Answer: B
Rationale: The correct answer is B: Mycobacterium leprae. This microorganism can only be cultured in the footpads of mice or a species of armadillo due to its specific growth requirements. Mycobacterium tuberculosis (choice A) can be cultured in various culture media in the laboratory. Neisseria gonorrhoeae (choice C) can be cultured on selective media like Thayer-Martin agar. Mycoplasma (choice D) can be cultured in cell cultures or specialized media. Therefore, the unique growth pattern of Mycobacterium leprae makes it the correct answer.
Drugs needed for diseases with fewer than 200,000 patients, and that fail to receive attention for development because of cost and need, are called:
- A. secondary drugs
- B. minor drugs
- C. orphan drugs
- D. specialty drugs
Correct Answer: C
Rationale: The correct answer is C: orphan drugs. Orphan drugs are medications developed to treat rare diseases affecting fewer than 200,000 patients. These diseases often lack attention from pharmaceutical companies due to the high cost and limited market potential. Orphan drugs receive special incentives and regulatory support to encourage their development.
A: Secondary drugs do not specifically refer to medications for rare diseases.
B: Minor drugs is not a recognized term in the context of rare disease medications.
D: Specialty drugs typically refer to high-cost medications used to treat complex or chronic conditions, but not necessarily rare diseases.