Individual nutrients are characterized by their ability to:

Correct Answer: B

Rationale: The correct answer is B: 'fulfill specific metabolic roles.' Nutrients play essential roles in specific metabolic processes in the body such as energy production, tissue repair, and growth. Choice A, 'work independently,' is incorrect as nutrients often work synergistically rather than alone. Choice C, 'influence weight loss,' is incorrect as while some nutrients may support weight loss indirectly through metabolic processes, it is not their primary characteristic. Choice D, 'improve mental status,' is also incorrect as while some nutrients are important for brain health, their primary role is not specifically to improve mental status.

Correct Answer: C

Rationale: The primary function of carbohydrates as a food source is to supply energy. Carbohydrates are the body's main source of energy, providing fuel for various physiological functions. Choice A is incorrect because carbohydrates do not primarily regulate metabolic processes; that role is mainly attributed to enzymes and hormones. Choice B is incorrect because proteins are primarily responsible for building body tissue. Choice D is incorrect because fiber, not all carbohydrates, provides bulk in the diet.

Correct Answer: A

Rationale: The correct answer is A: Glycogen. Glycogen is the stored form of carbohydrates in the body, primarily found in the liver and muscles. Starch (choice B) is a carbohydrate storage molecule in plants, not in the human body. Fat (choice C) is a different macronutrient and not the main storage form of carbohydrates. Glucose (choice D) is a simple sugar that serves as an energy source, not the main storage form of carbohydrates.

Correct Answer: B

Rationale: The correct answer is B: 120. Carbohydrates provide 4 kcal per gram, so 30 grams of carbohydrates will provide 120 kcal. This is calculated by multiplying the grams of carbohydrate (30) by the kcal per gram (4). Choices A, C, and D are incorrect because they do not reflect the correct calculation based on the energy content of carbohydrates.

Correct Answer: D

Rationale: The correct answer is D: 45% to 65%. Carbohydrates should contribute between 45% to 65% of the total daily caloric intake for healthy individuals to maintain a balanced diet. Choices A, B, and C are incorrect because they suggest lower ranges, which may not provide sufficient energy from carbohydrates for overall health and well-being.