Nokea
Listeria monocytogenes are:
- A. Gram-negative rod-shaped bacteria
- B. Gram-positive spherical bacteria
- C. Gram-positive rod-shaped bacteria
- D. None of the above
Correct Answer: C
Rationale: The correct answer is C: Gram-positive rod-shaped bacteria. Listeria monocytogenes is a Gram-positive bacterium, as it retains the crystal violet stain during the Gram staining process. The bacteria are rod-shaped, not spherical. Choice A is incorrect as Listeria monocytogenes is not Gram-negative. Choice D is incorrect as Listeria monocytogenes does fall under the category of Gram-positive bacteria. The key is to remember the characteristics of Listeria monocytogenes, which are Gram-positive and rod-shaped.
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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.
Which of the following bacteria is known for causing the disease known as whooping cough?
- A. Bordetella pertussis
- B. Clostridium tetani
- C. Haemophilus influenzae
- D. Staphylococcus aureus
Correct Answer: A
Rationale: The correct answer is A: Bordetella pertussis. This bacterium is known for causing whooping cough due to its ability to produce toxins that damage the respiratory tract, leading to severe coughing fits. Clostridium tetani causes tetanus, Haemophilus influenzae can cause respiratory infections but not whooping cough, and Staphylococcus aureus is more commonly associated with skin infections. Therefore, A is the correct choice based on its specific association with the disease in question.
Which type of RNA carries the genetic code for protein synthesis?
- A. mRNA
- B. tRNA
- C. rRNA
- D. snRNA
Correct Answer: A
Rationale: The correct answer is A: mRNA. mRNA carries the genetic code from the DNA in the cell nucleus to the ribosomes in the cytoplasm, where protein synthesis occurs. It serves as a template for protein synthesis by specifying the order of amino acids. tRNA (choice B) brings amino acids to the ribosome during protein synthesis. rRNA (choice C) is a structural component of ribosomes. snRNA (choice D) is involved in RNA processing and splicing, not protein synthesis. Therefore, choice A is correct as it directly carries the genetic code for protein synthesis.
A lot of pyoinflammatory processes in oral cavity are caused by anaerobes. What nutrient medium can be used for control of wound textile contamination by anaerobes?
- A. Kitt-Tarozzi
- B. Endo
- C. Roux
- D. Sabouraud's
Correct Answer: A
Rationale: The correct answer is A: Kitt-Tarozzi. This medium contains blood and hemin, which are essential nutrients for the growth of anaerobes. Blood provides a source of iron, while hemin stimulates the growth of anaerobes. This combination creates an environment conducive for the isolation and identification of anaerobic organisms.
B: Endo and C: Roux are selective media primarily used for the isolation of gram-negative bacteria and not specifically designed for anaerobes.
D: Sabouraud's is a medium used for the cultivation of fungi, not anaerobes.
In summary, Kitt-Tarozzi is the correct choice due to its specific nutrient composition that supports the growth of anaerobes, unlike the other options which are not suitable for this purpose.
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.