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: D

Rationale: Step-by-step rationale for why answer D is correct: 1. Tetanus exotoxins are produced by Clostridium tetani bacteria. 2. Once formed, the exotoxins can spread through the bloodstream. 3. Retrograde axonal transport allows the exotoxins to travel to the central nervous system (CNS). 4. In the CNS, the exotoxins can cause the symptoms of tetanus. 5. Options A, B, and C are incorrect as tetanus exotoxins do not follow those pathways. In summary, option D is correct as tetanus exotoxins can spread through the blood and reach the CNS via retrograde axonal transport, while the other options do not align with the known pathophysiology of tetanus.

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.

Correct Answer: A

Rationale: The correct answer is A because spores are heat-resistant and require high temperatures for destruction. Autoclaving at 121°C for 15-20 minutes ensures spore destruction due to the high pressure and temperature. Choice B (heating to 80°C) is insufficient to destroy spores. Choice C (boiling at 100°C for 10 minutes) is also inadequate as spores require higher temperatures for elimination. Choice D (None of them) is incorrect as autoclaving is the standard method for spore sterilization.

Correct Answer: C

Rationale: The correct answer is C, Meat-peptone agar, as it provides a simple nutritive media for bacterial growth. This agar contains meat extract and peptone, which are good sources of nutrients for bacterial growth. Glucose broth (A) is a liquid medium with glucose but lacks other essential nutrients. Ascites (serum) agar (B) is a selective medium used for detecting pathogens in clinical samples. Blood agar (D) is a differential medium used to distinguish different types of bacteria based on hemolytic reactions. Meat-peptone agar is the simplest and most general-purpose medium among the options provided.