Nokea
Which of the following proteins are encoded by herpesviruses and required for viral DNA replication?
- A. viral DNA polymerase
- B. ribonucleotide reductase
- C. neuraminidase
- D. thymidine kinase
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.
You may also like to solve these questions
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.
The correct hierarchical order for virus classification is
- A. order, genus, family, subfamily, species.
- B. species, genus, family, subfamily, order.
- C. order, family, subfamily, genus, species.
- D. genus, order, family, subfamily, species.
Correct Answer: C
Rationale: The correct hierarchical order for virus classification is order, family, subfamily, genus, species. This is because classification starts at a broader level (order) and narrows down to a more specific level (species). Order comes first to group viruses based on common characteristics, followed by family, which further categorizes them. Subfamily refines the classification, then genus groups similar viruses together, and species distinguishes different strains within a genus. Choice A is incorrect because it places genus before family, which is not the correct sequence. Choice B is incorrect as it starts with species, which is the most specific level. Choice D is incorrect because it places genus at the beginning, which is too specific for the hierarchical order.
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.
A man died from an acute disease characterized by fever, jaundice, hemorrhagic rash, and acute renal insufficiency. Histological examination revealed spiral bacteria shaped like 'C' and 'S' letters. Identify the pathogen.
- A. Leptospira
- B. Treponema
- C. Borrelia
- D. Spirochaeta
Correct Answer: A
Rationale: The correct answer is A: Leptospira. Leptospira is a spiral-shaped bacterium that causes a disease known as leptospirosis, characterized by fever, jajsondice, hemorrhagic rash, and renal insufficiency. The characteristic spiral shape of the bacteria, resembling 'C' and 'S' letters, is a key identifying feature. Leptospira is commonly associated with contaminated water sources and can be transmitted to humans through contact with infected animals or water.
Summary of other choices:
B: Treponema - Treponema pallidum is the causative agent of syphilis, which does not typically present with the combination of symptoms described in the question.
C: Borrelia - Borrelia species are associated with Lyme disease and relapsing fever, but do not match the specific symptoms and histological appearance described in the question.
D: Spirochaeta - Spirochaeta is a genus of bacteria, but specific species within
Which of the following bacteria is responsible for causing gonorrhea?
- A. Chlamydia trachomatis
- B. Neisseria gonorrhoeae
- C. Treponema pallidum
- D. Escherichia coli
Correct Answer: B
Rationale: The correct answer is B: Neisseria gonorrhoeae. This bacterium is responsible for causing gonorrhea. Neisseria gonorrhoeae is a sexually transmitted bacterium that infects the mucous membranes of the reproductive tract. It is known for causing symptoms such as painful urination and discharge. Chlamydia trachomatis (choice A) is another sexually transmitted bacterium but is not responsible for gonorrhea. Treponema pallidum (choice C) causes syphilis, not gonorrhea. Escherichia coli (choice D) is a common bacterium found in the gut and is not associated with causing gonorrhea. Therefore, Neisseria gonorrhoeae is the correct answer for this question.