Which of the following statements is true regarding polio vaccines:

Correct Answer: A

Rationale: The correct answer is A: Salk and Sabin vaccines are vaccines against polio. Both Salk and Sabin vaccines are indeed vaccines specifically developed to prevent polio. The Salk vaccine is an inactivated polio vaccine, while the Sabin vaccine is an oral live attenuated vaccine. Therefore, choice B is incorrect as the Sabin vaccine is live attenuated, not inactivated. Choice C is also incorrect because the Salk vaccine is inactivated, not live attenuated. Choice D is incorrect because not all statements are true; only statement A is accurate.

Correct Answer: A

Rationale: Rationale: 1. Listeria monocytogenes is a Gram-positive bacterium known for causing foodborne illnesses. 2. Gram-negative bacteria have a different cell wall structure than Gram-positive bacteria, making choice A correct. 3. Choice B is incorrect as Listeria monocytogenes is not encapsulated or sporulating. 4. Choice C is incorrect as Listeria monocytogenes does have a cell wall. 5. Choice D is incorrect as Listeria monocytogenes is indeed a Gram-positive coccobacilli.

Correct Answer: A

Rationale: The correct answer is A: Meningitides. H. Influenzae type b (Hib) is a bacterium known to cause meningitis, a serious infection of the protective membranes covering the brain and spinal cord. Hib does not typically cause tonsillitis, urinary tract infections, or gastroenteritis. Meningitis is a life-threatening condition that requires prompt treatment, making it crucial to identify Hib as the causative agent.

Correct Answer: B

Rationale: The correct answer is B: Trichomonas vaginalis. Trichomonas vaginalis is a protozoan parasite that can survive and grow in low moisture conditions. It does not require a host cell and can thrive in moist environments, making it able to grow on substances with very low moisture content. Giardia lamblia (A), Balantidium coli (C), and Entamoeba histolytica (D) are all parasites that require a host to survive and reproduce, making them unable to grow on substances with very low moisture content. Trichomonas vaginalis is the only organism among the choices that fits the criteria of being able to grow on low moisture substances.

Correct Answer: D

Rationale: The correct answer is D: Paramyxoviridae. Mumps virus is a member of the Paramyxoviridae family, based on its characteristics such as structure, genome organization, and replication cycle. Paramyxoviruses are enveloped, non-segmented RNA viruses with a helical nucleocapsid. They replicate in the cytoplasm and bud from the host cell membrane. Coronaviridae (A) are a different family of viruses with distinct characteristics. Picornaviridae (B) and Orthomyxoviridae (C) are also different families with unique features that do not match those of the mumps virus.