When an increase in exercise is accompanied by a decrease in body weight, it is an example of what?

Correct Answer: C

Rationale: When an increase in exercise is accompanied by a decrease in body weight, it demonstrates a negative correlation. This means that as one variable (exercise) increases, the other variable (body weight) decreases. Choice A, 'variable effect,' is vague and does not accurately describe the relationship between exercise and body weight. Choice B, 'positive correlation,' is incorrect because in a positive correlation, both variables would increase or decrease together. Choice D, 'randomization effect,' is unrelated to the scenario described.

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.

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.