Which type of RNA carries the genetic code for protein synthesis?

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.

Correct Answer: A

Rationale: The correct answer is A because fires from combustibles such as wood fall under Class A fires. Type A fire extinguishers are specifically designed to extinguish fires involving ordinary combustible materials like wood, paper, and cloth. Choice B, C, and D are incorrect because they do not correspond to the correct classification of the fire. Choice B refers to Class B fires involving flammable liquids, Choice C refers to Class C fires involving electrical equipment, and Choice D refers to Class D fires involving combustible metals. It is crucial to match the type of fire extinguisher with the type of fire to effectively combat the fire.

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.

Correct Answer: A

Rationale: The correct answer is A: viral DNA polymerase. This enzyme is essential for replicating the viral DNA during the herpesvirus life cycle. It catalyzes the synthesis of new DNA strands using the viral genomic template. Ribonucleotide reductase (B) is involved in nucleotide synthesis, but not directly in DNA replication. Neuraminidase (C) is an enzyme found in influenza viruses, not herpesviruses. Thymidine kinase (D) is an enzyme that phosphorylates thymidine, but its role is more related to nucleotide metabolism rather than viral DNA replication.

Correct Answer: B

Rationale: The correct answer is B: Thayer-Martin agar. This selective media contains antibiotics that inhibit the growth of other organisms while allowing Neisseria gonorrhoeae to grow. The antibiotics in Thayer-Martin agar include vancomycin, colistin, nystatin, and trimethoprim, which target different types of bacteria, ensuring the isolation of N. gonorrhoeae. Phenylethyl alcohol agar (A) is used to isolate gram-positive organisms, not N. gonorrhoeae. MacConkey agar (C) is selective for gram-negative enteric bacteria. Mannitol salt agar (D) is used for isolating Staphylococcus species based on their ability to ferment mannitol.