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.

Correct Answer: C

Rationale: The correct answer is C. An essential nutrient is a substance that is necessary for normal body functioning but cannot be synthesized in adequate amounts by the body, therefore it must be obtained from the diet. Choices A, B, and D are incorrect because essential nutrients are not synthesized by the body, they are necessary for body functioning, and they are not typically stored in the body for long periods.

Correct Answer: D

Rationale: The correct answer is D, Kilocalorie. The term kilocalorie, often referred to as a calorie, is the amount of heat required to raise the temperature of one kilogram of water by one degree Celsius. While Choice A, Calorie, is technically correct, it is not the most specific term for the described amount of heat. Choice B, Joule, is a unit of energy but not specifically related to the amount of heat required to raise the temperature of water. Choice C, Kilojoule, is also a unit of energy but not the precise term for the heat required to raise the temperature of water by one degree Celsius.

Correct Answer: B

Rationale: Difficulty breathing is a common symptom of congenital heart disease in infants. Infants with congenital heart disease may experience difficulty breathing due to impaired cardiac function, which affects the heart's ability to pump blood effectively. This symptom is often due to issues like heart failure or fluid accumulation in the lungs. Excessive weight gain (Choice A) is not typically associated with congenital heart disease in infants. High blood pressure (Choice C) is less common in infants with congenital heart disease compared to adults. Increased appetite (Choice D) is not a typical symptom of congenital heart disease in infants.

Correct Answer: A

Rationale: Topical corticosteroids are the correct answer for a child with moderate to severe eczema. These medications are commonly used to reduce inflammation and itching associated with eczema. Oral antibiotics (Choice B) are not typically used in eczema treatment unless there is a secondary bacterial infection. Frequent saline irrigation (Choice C) may aid in wound care but is not a primary treatment for eczema. A high-calcium diet (Choice D) is not a standard treatment for eczema and does not target the underlying inflammatory process that causes eczema symptoms.