Which of the following statements concerning vitamin C functions are true:

Correct Answer: D

Rationale: Rationale: 1. Vitamin C is known for its antioxidant properties, which help in neutralizing free radicals and protecting cells from damage. 2. It is required for hydroxylation reactions, such as converting proline to hydroxyproline for collagen synthesis, essential for maintaining connective tissues. 3. Vitamin C does not function as pyridoxal phosphate (choice A) or a constituent of coenzyme A (choice B). 4. While vitamin C is involved in one-carbon metabolism, it does not directly act as a carrier of one-carbon groups as described in choice C. Summary: The correct answer (D) highlights the antioxidant properties and the role of vitamin C in hydroxylation reactions for collagen synthesis. Choices A, B, and C are incorrect as they misrepresent the functions of vitamin C.

Correct Answer: B

Rationale: The correct route of administration for vitamin D3 is oral (Choice B) because it is a fat-soluble vitamin that can be effectively absorbed through the digestive system. Subcutaneous (Choice A) and intravenous (Choice C) routes are not typically used for vitamin D3 as it can lead to potential risks and complications. Intranasal (Choice D) administration is not a common route for vitamin D3 absorption, as it may not provide adequate bioavailability compared to oral ingestion. Therefore, the oral route is the most appropriate and efficient method for administering vitamin D3.

Correct Answer: D

Rationale: The correct answer is D: Fractures. Plicamycin is not known to cause fractures. Thrombocytopenia, GI toxicity, and bleeding disorders are potential unwanted effects of plicamycin due to its impact on bone marrow and gastrointestinal tract. It is crucial to recognize that fractures are not a documented side effect of plicamycin, making option D the correct answer.

Correct Answer: D

Rationale: Rationale: 1. Choice A is correct because combining antimicrobial agents can enhance their effectiveness against resistant strains. 2. Choice B is correct because a combination can target a wider range of microorganisms. 3. Choice C is correct because using a combination can help reduce the chance of resistance developing. Summary: All of the above choices are correct because rational antimicrobial combinations provide synergism, broad coverage, and prevent resistance emergence.

Correct Answer: C

Rationale: The correct answer is C: "Does not demonstrate nephrotoxicity." Amphotericin B is known for its nephrotoxicity, which can lead to kidney damage. This is a well-documented side effect of the drug. Choices A, B, and D are incorrect because Amphotericin B is indeed used for systemic mycosis treatment, poorly absorbed from the gastrointestinal tract, and influences the permeability of fungus cell membrane, making them true characteristics of the drug.