The main structural components of viruses are

Correct Answer: A

Rationale: Step-by-step rationale for choice A: 1. Viruses contain genetic material in the form of nucleic acids (DNA or RNA). 2. Proteins are essential for the structure and function of viral particles. 3. Nucleic acids (genetic material) and proteins are the two main components of viruses. 4. Therefore, choice A (nucleic acid and proteins) is correct. Summary: - Choice B (nucleic acids and lipids) is incorrect as lipids are not a main structural component of viruses. - Choice C (lipids and proteins) is incorrect as nucleic acids are essential components of viruses. - Choice D (proteins and glycoproteins) is incorrect as glycoproteins are a type of protein and not a separate component in viruses.

Correct Answer: B

Rationale: The correct answer is B because anaerobic bacteria can grow in environments without oxygen. Anaerobic bacteria do not require oxygen for their metabolism and energy production. They can thrive in oxygen-deprived conditions by using alternative electron acceptors. Choice A is incorrect because anaerobic bacteria do not require oxygen to survive. Choice C is incorrect because anaerobic bacteria typically cannot survive in the presence of high concentrations of oxygen. Choice D is incorrect because anaerobic bacteria do not perform photosynthesis.

Correct Answer: A

Rationale: The correct answer is A: Nystatin. Nystatin is an antifungal medication, not an antibiotic used to treat bacterial infections like generalized meningococcal infection. Penicillin G, macrolides, and chloramphenicol are antibiotics commonly used to treat bacterial infections, including meningococcal infections. Penicillin G is the drug of choice for meningococcal infections, while macrolides and chloramphenicol are alternative options. Nystatin is not effective against bacteria, so it is not a suitable treatment for meningococcal infections.

Correct Answer: C

Rationale: Step 1: The nucleocapsid is the structure containing the viral genome and the protein capsid. Step 2: The genome carries the genetic material of the virus. Step 3: The capsid is the protein coat that encloses and protects the viral genome. Step 4: Therefore, the correct answer is C: Genome and capsid. Summary: A: Capsid and spikes - Incorrect, spikes are not part of the nucleocapsid. B: Genome and envelop - Incorrect, the envelop is not part of the nucleocapsid. D: Capsid and envelope - Incorrect, the envelope is not part of the nucleocapsid.

Correct Answer: D

Rationale: The correct answer is D, Salmonella typhi, because it is a motile bacterium due to possessing flagella that aid in movement. Bacillus anthracis (A) is non-motile, Klebsiella pneumoniae (B) lacks flagella for motility, and Shigella flexneri (C) is non-motile as well. Salmonella typhi (D) is known for its flagella-driven motility, allowing it to move and spread within its host and environment. Flagella are essential for bacterial motility, enabling them to navigate and colonize different environments efficiently.

Correct Answer: D

Rationale: The correct answer is D: To determine the children that need to receive BCG vaccination. The Mantoux test is used to identify individuals who have been exposed to Tuberculosis (TB) and need BCG vaccination for protection. Parotitis (choice A) is a viral infection unrelated to TB. Allergization rate toward rickettsia (choice B) and immune stress toward diphtheria (choice C) are not related to the Mantoux test or BCG vaccination. Therefore, choice D is the correct answer as it aligns with the purpose of the Mantoux test.

Correct Answer: A

Rationale: Rationale: A is incorrect because whooping cough resurgence is mainly due to decreased vaccine immunity, not changing antigenicity. B is correct as P. aeruginosa can indeed cause infections with blue-green pus due to its pigment production. C is correct as H. influenzae type b capsule is a virulence factor contributing to invasive disease. D is correct as Legionella infection is acquired via inhalation of contaminated water aerosols. Therefore, A is incorrect as the rise in whooping cough is not due to changing antigenicity but vaccine immunity decline.

Correct Answer: D

Rationale: The correct answer is D: rabbit fever. Tularemia is commonly known as rabbit fever due to the fact that it is often contracted through handling infected rabbits or other rodents. This zoonotic disease is caused by the bacterium Francisella tularensis. Scarlet fever (A) is a streptococcal infection characterized by a rash, not related to tularemia. Strep throat (B) is a bacterial infection caused by Streptococcus bacteria and is not associated with tularemia. Cat scratch fever (C) is caused by Bartonella henselae and typically transmitted through cat scratches or bites, not related to tularemia.

Correct Answer: D

Rationale: The correct answer is D (15-Oct) because boiling items for at least 15 minutes is necessary to effectively kill most vegetative bacteria and viruses. This duration ensures that the water reaches a high enough temperature to destroy harmful microorganisms. Choices A, B, and C are incorrect because they do not provide a sufficient amount of time for the water to reach the necessary temperature to effectively kill bacteria and viruses. Shorter durations may not be effective in ensuring food safety.