What is the result of the metabolism of energy nutrients?

Correct Answer: A

Rationale: The correct answer is A. Energy is released during the metabolism of energy nutrients. This released energy is utilized by the body for various functions. Choice B is incorrect because the metabolism of energy nutrients does not directly result in an increase in body fat. Choice C is incorrect as energy is not destroyed but rather transformed and utilized by the body. Choice D is incorrect as the metabolism of energy nutrients does not lead to a decrease in body water.

Correct Answer: D

Rationale: The Recommended Dietary Allowances (RDAs) are the best measure to describe the amounts of nutrients that should be consumed by the population. RDAs represent the average daily intake level that meets the nutrient requirements of nearly all (97-98%) healthy individuals in a particular life stage and gender group. Choice A, the Dietary Reference Intakes, provide a set of nutrient intake values but do not specifically address the average daily amount of a nutrient considered adequate for practically all individuals. Choice B, the Tolerable Upper Intake levels, focus on the maximum daily amount of a nutrient deemed safe for most healthy people, not the average daily amount needed. Choice C, the Estimated Average Requirements, reflect the average daily amount of a nutrient needed by half of the healthy individuals, which is not as comprehensive as the RDAs that cater to nearly all healthy people.

Correct Answer: D

Rationale: The correct answer is D. A placebo serves as a control for comparison with the treatment group, helping to eliminate bias and ensure the results are due to the treatment itself. Placebos are crucial in research to distinguish the actual effect of the treatment from psychological or subjective factors. Choice A is incorrect because the purpose of a placebo is not related to reducing the cost of the experiment. Choice B is incorrect because while placebos are used in double-blind studies, their primary purpose is not to make the experiment double-blind. Choice C is incorrect because the purpose of a placebo is not to increase the number of participants but rather to serve as a comparison group for the treatment being tested.

Correct Answer: D

Rationale: Glucose is the correct answer as it is the primary source of energy for the brain and nervous system. The brain relies heavily on glucose to function optimally. While protein and fat play essential roles in the body, they are not the primary sources of energy for the brain and nervous system. Carbohydrates, on the other hand, are broken down into glucose, which is then used as fuel by the brain and nervous system.

Correct Answer: A

Rationale: The main purpose of Recommended Dietary Allowances (RDAs) is to provide guidelines for nutrient intakes that meet the needs of most healthy people. Choice B is incorrect because RDAs aim beyond just survival requirements. Choice C is incorrect because establishing maximum safe levels is the role of Tolerable Upper Intake Levels (ULs). Choice D is incorrect because preventing chronic diseases is more associated with Dietary Reference Intakes (DRIs) like Adequate Intakes (AIs) and Tolerable Upper Intake Levels (ULs). Therefore, the correct answer is A.