Correct Answer: A

Rationale: Carbohydrates are the body's primary source of energy. When carbohydrates are consumed, they are broken down into glucose, which is used by the body's cells for energy production. Fats and proteins are also essential nutrients, but carbohydrates are the preferred energy source for the body due to their quick conversion into fuel. Vitamins are not a direct source of energy but play crucial roles in various bodily functions.

Correct Answer: A

Rationale: The correct answer is iron. Iron is essential for enzyme function and energy production within the mitochondria. While cobalt is important for certain enzymes, it is not the primary mineral involved in this specific function. Hemoglobin is a protein in red blood cells that carries oxygen, not a mineral involved in enzyme actions. Vitamin B12 is crucial for nerve function and DNA synthesis but is not directly related to controlling enzyme actions in mitochondria.

Correct Answer: D

Rationale: The Exchange Lists for Meal Planning categorize foods based on their macronutrient content, such as carbohydrate, protein, and fat. These lists help individuals make food choices while ensuring similar amounts of macronutrients are consumed. Therefore, the correct answer is D. Choices A, B, and C are incorrect because Exchange Lists focus on macronutrient content, not weight, serving size, or micronutrient content.

Correct Answer: B

Rationale: The correct answer is 'B: amino.' Amino acids are the fundamental units that make up proteins. They are essential for various bodily functions, including building and repairing tissues. Choice A, 'fatty acids,' are not the basic building blocks of proteins but rather a type of lipid. Choice C, 'nucleic acids,' are the building blocks of nucleic acids like DNA and RNA, not proteins. Choice D, 'omega fatty acids,' are a specific type of fatty acid known for their health benefits but are not directly related to the building blocks of proteins.

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.