Nokea
Which type of bacteria can survive in extreme salty environments?
- A. Psychrophiles
- B. Halophiles
- C. Thermophiles
- D. Mesophiles
Correct Answer: B
Rationale: The correct answer is B: Halophiles. Halophiles are bacteria that can survive in extreme salty environments. They have adapted to thrive in high salt concentrations. Psychrophiles (A) thrive in cold temperatures, Thermophiles (C) thrive in high temperatures, and Mesophiles (D) thrive in moderate temperatures. Therefore, they are not adapted to survive in extreme salty environments like Halophiles.
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Anticodon is:
- A. Produced during the process of replication
- B. A nucleotide triplet on the molecule of mRNA
- C. A nucleotide DNA triplet defining the amino acid which has a specific sequence on the polypeptide chain during the translation
- D. A nucleotide triplet forming a unit of genetic code in a transfer RNA molecule corresponding to a complementary codon on messenger RNA
Correct Answer: D
Rationale: The correct answer is D because an anticodon is a nucleotide triplet in a tRNA molecule that pairs with a complementary codon on mRNA during translation. Step 1: Anticodons are found in tRNA, not in DNA or mRNA. Step 2: Anticodons specifically bind to codons on mRNA to ensure correct amino acid incorporation into the growing polypeptide chain, making option D the most accurate choice. Option A is incorrect as replication does not involve anticodons. Option B is incorrect because codons, not anticodons, are found on mRNA molecules. Option C is incorrect as it describes a codon on DNA, not an anticodon on tRNA.
Family Parvoviridae can cause all of these, except:
- A. Aplastic crisis in patients with chronic anemia
- B. Herpangina
- C. Fetal infections
- D. Fifth disease
Correct Answer: B
Rationale: The correct answer is B: Herpangina. Family Parvoviridae includes Parvovirus B19, which causes Fifth disease, aplastic crisis in chronic anemia, and fetal infections. Herpangina is caused by Enteroviruses, not Parvoviridae. Parvovirus B19 specifically targets erythroid progenitor cells, leading to anemia in susceptible individuals. Fetal infections can result in hydrops fetalis. Aplastic crisis occurs in patients with chronic anemia due to suppression of erythropoiesis by the virus.
Which of the following bacteria is associated with food poisoning caused by improperly canned foods?
- A. Clostridium botulinum
- B. Escherichia coli
- C. Salmonella enterica
- D. Vibrio cholerae
Correct Answer: A
Rationale: The correct answer is A: Clostridium botulinum. This bacterium is associated with food poisoning from improperly canned foods due to its ability to produce botulinum toxin, a potent neurotoxin that causes botulism. Improper canning allows spores of Clostridium botulinum to survive and germinate, producing the toxin in anaerobic conditions. The other choices are incorrect because Escherichia coli, Salmonella enterica, and Vibrio cholerae are not typically associated with food poisoning from improperly canned foods. Escherichia coli and Salmonella are more commonly linked to contaminated water or undercooked food, while Vibrio cholerae causes cholera primarily through contaminated water sources.
When examining a patient with a suspicion of food toxicoinfection, a doctor on duty has detected symptoms characteristic of botulism. The patient named the meals he had eaten the day before. What is the most probable cause of infection?
- A. Homemade canned meat
- B. Custard pastry from private bakery
- C. Sour cream from local dairy factory
- D. Strawberries from suburban vegetable garden
Correct Answer: A
Rationale: The correct answer is A: Homemade canned meat. Botulism is often caused by consuming improperly canned or preserved foods, particularly meats. The spores of the Clostridium botulinum bacteria can grow in anaerobic conditions, such as those found in improperly canned foods, leading to the production of the botulinum toxin. The symptoms of botulism align with those characteristic of the patient's condition.
Explanation of why the other choices are incorrect:
B: Custard pastry from private bakery - Unlikely to be the cause of botulism as this type of food is not typically associated with the growth of Clostridium botulinum.
C: Sour cream from local dairy factory - While dairy products can sometimes be sources of foodborne illness, botulism is not commonly associated with sour cream.
D: Strawberries from suburban vegetable garden - Botulism is not typically transmitted through fresh fruits or vegetables, making this an unlikely source of infection.
Which form of human plague is present with high fever and large lymphadenopathies (buboes). The case fatality in untreated cases may reach 60%.
- A. Bubonic plague
- B. Pneumonic plague
- C. Gastrointestinal plague
- D. Septicemic plague
Correct Answer: A
Rationale: The correct answer is A: Bubonic plague. Bubonic plague is characterized by high fever and large swollen lymph nodes (buboes). The case fatality rate in untreated cases can reach 60%. This form of plague is typically transmitted through the bite of an infected flea.
B: Pneumonic plague presents with respiratory symptoms and is transmitted through respiratory droplets.
C: Gastrointestinal plague is not a recognized form of plague.
D: Septicemic plague is a severe form of plague where the bacteria multiply in the bloodstream. It may not always present with buboes.