why is it important to use randomization in a scientific experiment
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HESI PN Nutrition Practice Exam

1. Why is randomization important in a scientific experiment?

Correct answer: B

Rationale: Randomization is crucial in a scientific experiment to eliminate bias in the assignment of subjects to groups. By randomly assigning subjects, it helps ensure that any differences observed in the outcomes are due to the experimental treatment and not to preexisting differences between groups. Choice A is incorrect because randomization does not guarantee representativeness but rather minimizes the impact of confounding variables. Choice C is not entirely accurate; while randomization can contribute to accuracy and validity, its primary purpose is to reduce bias. Choice D is incorrect as the goal of randomization is not to balance the number of subjects but to prevent systematic differences between groups.

2. How should a caregiver manage a child with a new diagnosis of sickle cell anemia?

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.

3. What is a common sign of congenital hip dysplasia in infants?

Correct answer: B

Rationale: Limited range of motion in the hip, often noted as a limitation in abduction, is a common sign of congenital hip dysplasia. This limitation is due to the abnormal development of the hip joint, affecting its movement. Symmetrical hip movement (Choice A) is not a characteristic sign of congenital hip dysplasia. Swelling of the knees (Choice C) is not typically associated with this condition. Dislocated patella (Choice D) refers to a different anatomical structure and is not a common sign of congenital hip dysplasia.

4. What is a key dietary consideration for a child with phenylketonuria (PKU)?

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.

5. 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.

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