What is the primary purpose of a placebo in an experiment?

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: 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.

Correct Answer: D

Rationale: The correct answer is D. Carbohydrates are the body's primary source of energy, fueling daily activities and bodily functions. Choice A is incorrect because insulation and organ support are primarily provided by adipose tissue and structural proteins, not carbohydrates. Choice B is incorrect because the regulation of body temperature is mainly controlled by processes like sweating and shivering, not carbohydrates. Choice C is incorrect because structural components like proteins are responsible for building tissues and organs, not carbohydrates.

Correct Answer: C

Rationale: Corrected Question: Vitamin C is considered a micronutrient because it is required in small amounts for proper body functioning and is essential for health. Proteins, carbohydrates, and fats are macronutrients, needed in larger quantities for energy and other body functions. Vitamin C, being a micronutrient, plays a crucial role in various bodily functions even though it is needed in smaller quantities compared to macronutrients. Therefore, the correct answer is C. Choice A (Protein), Choice B (Carbohydrate), and Choice D (Fat) are incorrect as they are macronutrients required in larger amounts for energy and other body functions.

Correct Answer: B

Rationale: Promoting adequate hydration and pain management is crucial for managing sickle cell anemia to prevent crises and complications. Adequate hydration helps prevent sickling of red blood cells, while effective pain management is essential for addressing the frequent pain episodes associated with the condition. Ensuring the child receives frequent blood transfusions is not the initial management for sickle cell anemia; transfusions are usually reserved for specific complications. Restricting physical activity should be individualized based on the child's condition; some physical activity is beneficial for overall health. Administering high doses of vitamin C is not a standard treatment for sickle cell anemia and does not address the underlying pathology of the disease.