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: 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: A

Rationale: Encouraging joint mobility and physical therapy is crucial in managing juvenile idiopathic arthritis (JIA). This approach helps maintain joint function, reduce stiffness, and improve the overall quality of life for children with JIA. Restricting all forms of exercise (Choice B) is not recommended, as appropriate physical activity is beneficial for joint health and overall well-being. Increasing sugar intake (Choice C) is not a recommended practice for managing JIA, as a healthy diet is important for overall well-being and can help reduce inflammation. Using only oral medications (Choice D) may not be sufficient for managing JIA, as a comprehensive treatment plan often includes a combination of medications, physical therapy, and other interventions to effectively manage the condition.

Correct Answer: B

Rationale: Limited abduction of the hip is a common sign of developmental dysplasia of the hip in infants. It indicates possible hip dislocation or instability, making it a key clinical manifestation to assess for DDH. Dislocated patella (Choice A) is not typically associated with DDH. Swelling of the knee (Choice C) and hyperextension of the leg (Choice D) are not specific signs linked to DDH in infants, further supporting why they are incorrect choices.

Correct Answer: B

Rationale: A low-phenylalanine diet is crucial for managing PKU to prevent neurological damage and maintain normal development. Phenylalanine is an amino acid found in protein-containing foods, and individuals with PKU have difficulty metabolizing it. Consuming foods low in phenylalanine helps prevent the buildup of toxic byproducts in the body. Choices A, C, and D are incorrect. A high-fiber diet, increased dairy intake, and high-sodium diet are not specific dietary considerations for PKU management. In fact, dairy products are a source of protein and phenylalanine, which should be limited in PKU.

Correct Answer: A

Rationale: Iron supplements are the correct choice for treating iron-deficiency anemia in children. Iron supplements help replenish the low iron levels in the body, addressing the underlying cause of the anemia. High-protein diets may be beneficial for overall health but are not the primary treatment for iron-deficiency anemia. Vitamin B12 injections are used to treat B12 deficiency anemia, a different type of anemia. Sodium chloride solution is not a treatment for anemia and is typically used for hydration purposes.

Correct Answer: B

Rationale: The correct answer is B: Ensure strict infection control measures. Children with acute lymphoblastic leukemia (ALL) who are undergoing chemotherapy have compromised immune systems, making them highly susceptible to infections. Implementing strict infection control measures, such as hand hygiene, limiting exposure to sick individuals, and maintaining a clean environment, is essential to prevent infections. Choice A is incorrect because avoiding all physical activity may not be necessary as long as the child's activity level is appropriate. Choice C is incorrect because increasing daily caloric intake is important to support the child's nutritional needs during treatment. Choice D is incorrect because limiting fluid intake is not typically recommended unless specifically advised by the healthcare provider.

Correct Answer: B

Rationale: When administering medications to a child with hepatic dysfunction, it is crucial to make adjustments in dosage due to altered metabolism. Hepatic dysfunction can affect the way medications are metabolized in the body, potentially leading to drug toxicity or reduced effectiveness. This is why adjusting the dosage is essential to ensure the medication is both safe and efficient. Choices A, C, and D are incorrect because increasing dosing intervals, avoiding all medications, or using only topical medications do not address the specific issue of altered drug metabolism in hepatic dysfunction.

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.