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 correct answer is A: Joint swelling and pain. These are the most common initial symptoms of juvenile idiopathic arthritis, typically affecting multiple joints. Skin rash (choice B), gastrointestinal bleeding (choice C), and neurological deficits (choice D) are not typical initial symptoms of juvenile idiopathic arthritis. Skin rash may be seen in other conditions like dermatitis or systemic lupus erythematosus, gastrointestinal bleeding may be associated with conditions like inflammatory bowel disease, and neurological deficits could be indicative of conditions like multiple sclerosis.

Correct Answer: C

Rationale: To calculate the percentage of total energy contributed by fat, first determine the energy from fat by multiplying the fat amount (30g) by the energy density of fat (9 kcal/g), which equals 270 kcal. Then, divide the energy from fat (270 kcal) by the total energy intake (1400 kcal) and multiply by 100 to find the percentage: (270 kcal / 1400 kcal) * 100 = 19.29% ≈ 19.00%. Therefore, fat contributes approximately 19% of the total energy in the diet. Choice A (8.50%) is too low, while choices B (15.00%) and D (25.50%) are incorrect calculations based on the given information.

Correct Answer: B

Rationale: The correct answer is B: Daily chest physiotherapy. Daily chest physiotherapy is essential in cystic fibrosis as it helps in clearing mucus from the lungs, reducing the frequency of respiratory infections. Antibiotics (Choice A) may treat infections but are not the key preventive measure. Increased fluid intake (Choice C) and dietary supplements (Choice D) can be beneficial for overall health but do not directly prevent recurrent respiratory infections in children with cystic fibrosis.

Correct Answer: B

Rationale: In laryngotracheobronchitis (croup), a child may become restless due to poor oxygenation. Increasing the oxygen concentration in the oxygen tent is crucial to improve oxygenation levels and manage symptoms effectively. Restraint is not appropriate in this situation, as it may cause distress and worsen the child's condition. Taking the child to the playroom is not indicated when the child requires oxygen therapy. While comforting the child is important, the priority in this scenario is to optimize oxygen delivery to improve respiratory distress.

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: A bulging fontanel is a key sign of meningitis in infants, indicating increased intracranial pressure due to inflammation of the meninges. This can lead to the fontanel bulging. Choices A, C, and D are incorrect. Increased appetite is not typically associated with meningitis in infants; instead, they may have poor feeding. A decreased respiratory rate is not a common sign of meningitis in infants. Elevated blood pressure is also not a typical finding in infants with meningitis.

Correct Answer: C

Rationale: The correct answer is C: Epinephrine injection. An epinephrine injection is the primary treatment for an anaphylactic reaction in children. Epinephrine acts quickly to reverse severe symptoms such as difficulty breathing, low blood pressure, and hives. Oral antihistamines, although useful for milder allergic reactions, are not sufficient to manage the potentially life-threatening symptoms of anaphylaxis. Intravenous fluids may be necessary to support blood pressure in a child with anaphylaxis but are not the primary treatment. Antipyretics, on the other hand, are medications used to reduce fever and are not indicated as the primary treatment for an anaphylactic reaction.

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.