Nokea
For filoviruses is true that:
- A. They are the most common cause of gastroenteritis
- B. They can be investigated in specifically equipped laboratories with a high level of biological protection
- C. They are widespread
- D. Mass immunization for specific prophylaxis is used in some countries
Correct Answer: B
Rationale: The correct answer is B because filoviruses, such as Ebola virus, require investigation in specifically equipped laboratories with high biological protection due to their high pathogenicity and risk of transmission. This is essential for ensuring the safety of researchers and preventing outbreaks.
A: This is incorrect as filoviruses are not the most common cause of gastroenteritis; they primarily cause severe hemorrhagic fevers.
C: Filoviruses are not widespread; they are typically confined to specific regions during outbreaks.
D: Mass immunization is not used for filoviruses as there is no established vaccine for general prophylaxis.
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The net gain of ATP molecules after the breakdown of one glucose molecule in glycolysis is
- A. 1
- B. 2
- C. 3
- D. 4
Correct Answer: B
Rationale: The correct answer is B (2). During glycolysis, one glucose molecule is broken down into two molecules of pyruvate. In this process, a net gain of 2 ATP molecules is produced through substrate-level phosphorylation. Specifically, ATP is generated during the conversion of glyceraldehyde-3-phosphate to 1,3-bisphosphoglycerate and during the conversion of phosphoenolpyruvate to pyruvate. The other choices are incorrect because the net gain of ATP molecules in glycolysis is not 1, 3, or 4; it is 2 based on the specific enzymatic reactions involved in the pathway.
A patient with pneumonia had sputum cultured on Endo agar, revealing red colonies. The bacteria were Gram-negative rods. What is the most likely causative agent?
- A. Escherichia coli
- B. Klebsiella pneumoniae
- C. Pseudomonas aeruginosa
- D. Proteus mirabilis
Correct Answer: A
Rationale: Rationale for correct answer (A: Escherichia coli):
1. Endo agar selects for Gram-negative bacteria.
2. Red colonies on Endo agar indicate lactose fermentation, characteristic of E. coli.
3. E. coli is a common cause of pneumonia, especially in immunocompromised patients.
Summary of why other choices are incorrect:
- B: Klebsiella pneumoniae: Typically forms mucoid colonies on agar.
- C: Pseudomonas aeruginosa: Produces characteristic greenish-blue colonies on agar.
- D: Proteus mirabilis: Does not typically ferment lactose, so would not produce red colonies on Endo agar.
Which of the following bacteria produces a neurotoxin that causes botulism?
- A. Clostridium botulinum
- B. Clostridium tetani
- C. Escherichia coli
- D. Staphylococcus aureus
Correct Answer: A
Rationale: The correct answer is A: Clostridium botulinum. Clostridium botulinum produces the neurotoxin that causes botulism. This bacterium thrives in anaerobic conditions and contaminated food. The neurotoxin blocks acetylcholine release at the neuromuscular junction, leading to muscle paralysis. Choices B, C, and D are incorrect because Clostridium tetani causes tetanus, Escherichia coli can cause food poisoning but not botulism, and Staphylococcus aureus produces enterotoxins causing food poisoning, not botulism.
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.
How is detected viral multiplication in cell culture
- A. by the presence of a specific cytopathic effect
- B. by using of an immunofluorescence detection method
- C. the characteristic type of viral colonies
- D. A and B both
Correct Answer: D
Rationale: The correct answer is D (A and B both). In viral multiplication, the presence of a specific cytopathic effect (CPE) in cell culture indicates viral replication. This is detected visually through changes in cell morphology. Additionally, immunofluorescence detection methods can be used to detect viral antigens within infected cells, confirming viral multiplication. Options C is incorrect as viral colonies are not typically used to detect viral multiplication in cell culture. Option B alone is not sufficient as it only focuses on immunofluorescence detection, while option A alone may not always be specific. Therefore, the combination of A and B provides a more comprehensive and accurate detection method for viral multiplication in cell culture.