Correct Answer: D

Rationale: Macronutrients are nutrients required by the body in large amounts to provide energy and include carbohydrates, fats, and proteins. While protein is essential for the body, it is not classified as a macronutrient. Proteins are made up of amino acids and serve various functions in the body, such as building and repairing tissues, but they are not a direct energy source like carbohydrates and fats. Therefore, protein is the exception among the listed options, making it the correct answer. Choice A, Fat, Choice B, Polyunsaturated fatty acids, and Choice C, Carbohydrate, are all examples of macronutrients that provide energy and support various bodily functions.

Correct Answer: C

Rationale: The hypothalamus, located in the middle of the brain, plays a crucial role in regulating hunger and satiety. It contains specific regions that control appetite and feeding behavior. The Medulla Oblongata (Choice A) is responsible for regulating vital functions like heartbeat and breathing, not hunger. The Pituitary Gland (Choice B) is an endocrine gland that secretes hormones but is not primarily involved in hunger regulation. The Parathyroid (Choice D) is responsible for regulating calcium levels in the body and not related to hunger or satiety.

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: A deficiency in iron can lead to various symptoms, such as microcytic anemia, fatigue, faulty digestion, blue sclerae, pale conjunctivae, and tachycardia. Iron-deficiency anemia may be caused by inadequate dietary intake; accelerated demand or losses; and inadequate absorption secondary to diarrhea, decreased acid secretions, or antacid therapy. Iron deficiency is frequently the result of postnatal feeding practices and has a serious impact on growth and mental and psychomotor development in infants and children. Choices A, C, and D are incorrect as zinc deficiency typically presents with symptoms like impaired wound healing, taste abnormalities, and hair loss; sodium deficiency can lead to symptoms such as muscle cramps, dizziness, and confusion; and potassium deficiency may cause muscle weakness, fatigue, and abnormal heart rhythms.