Which physiologic role does vitamin C play in the body?

Correct Answer: C

Rationale: Vitamin C plays a crucial role in protecting the integrity of cellular membranes. It is essential for collagen synthesis, which is important for wound healing and maintaining skin, blood vessels, and other tissues. Choice A is incorrect as the transcription of DNA to RNA is facilitated by vitamin A. Choice B is incorrect as calcium absorption and regulation are functions of vitamin D. Choice D is incorrect as vitamin K serves as a catalyst for the synthesis of blood-clotting factors, not vitamin C.

Correct Answer: A

Rationale: The correct answer is A: 'Blood clotting, transmission of nerve impulses, muscle contraction and relaxation.' Calcium plays a crucial role in various physiological functions such as blood clotting, transmission of nerve impulses, muscle contraction and relaxation, membrane permeability, and activation of certain enzymes. Choice B is incorrect because while calcium is involved in calcium homeostasis, it is not the only role it plays in the body. Choice C is incorrect as calcium indeed has several known metabolic functions, and it is not solely for preventing caries. Choice D is also incorrect as the functions mentioned are primarily carried out by other nutrients and not specifically by calcium.

Correct Answer: D

Rationale: The correct answer is D. Phosphorus plays a crucial role in ATP energy release, the metabolism of fats, carbohydrates, and proteins, and regulation of acid-base balance. Choices A, B, and C are incorrect. Phosphorus is not directly involved in blood clotting, transmission of nerve impulses, muscle contraction, or calcium homeostasis. It also has known metabolic functions and is not associated with caries prevention.

Correct Answer: B

Rationale: The correct answer is B. Magnesium plays an important role in maintaining calcium homeostasis and preventing skeletal abnormalities. It is involved in more than 300 enzymatic reactions, including energy metabolism, insulin activity, and glucose use. Magnesium is vital to the structural integrity of heart muscle and other muscles and nerves. While magnesium does play a role in blood clotting, nerve impulses, muscle contraction, relaxation, ATP energy release, and metabolism of fats, carbohydrates, proteins, the primary physiologic role of magnesium in the body is related to calcium homeostasis and maintaining the structural integrity of the heart muscle. Choice A is incorrect because it includes functions of magnesium, but they are not its primary physiologic role. Choice C is incorrect as magnesium has several known metabolic functions. Choice D is incorrect because although magnesium is involved in ATP energy release and metabolism, its primary role is related to calcium homeostasis and structural integrity of muscle.

Correct Answer: A

Rationale: Wernicke-Korsakoff syndrome is indeed associated with thiamine (vitamin B1) deficiency. This syndrome is commonly seen in individuals with chronic alcoholism due to poor diet and impaired thiamine absorption. Thiamine is essential for normal brain function and energy metabolism. Riboflavin (B2) deficiency can lead to symptoms like sore throat and swollen mucous membranes, not Wernicke-Korsakoff syndrome. Niacin (B3) deficiency causes pellagra, characterized by dermatitis, diarrhea, dementia, and death, but not Wernicke-Korsakoff syndrome. Pyridoxine (B6) deficiency can result in dermatitis, glossitis, and peripheral neuropathy, but it is not associated with Wernicke-Korsakoff syndrome.