Nokea
You have been asked to help a top nutrition researcher conduct human experiments on vitamin C. As the subjects walk into the laboratory, you distribute all the vitamin C pill bottles to the girls and all the placebo pill bottles to the boys. What should you have done?
- A. Giving all the boys the vitamin C and the girls the placebo, and telling them what they were getting.
- B. Distributing the bottles randomly, randomizing the subjects, and telling them what they were getting.
- C. Telling the subjects which group they were in, but preventing yourself from knowing the contents of the pill bottles.
- D. Preventing yourself from knowing what is in the pill bottles, and distributing the bottles randomly to the subjects.
Correct Answer: D
Rationale: The correct approach in a scientific experiment is to prevent yourself from knowing the contents of the pill bottles and distribute them randomly to the subjects. This randomization helps to avoid bias and ensures that the results are not influenced by preconceived notions. Option A is incorrect because it introduces gender bias by assigning pills based on gender. Option B is incorrect as it mentions telling the subjects what they are getting, which could lead to placebo effects. Option C is incorrect as it suggests disclosing group information to the subjects, which can also introduce bias.
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The parents of a child with sickle cell anemia ask why their child experiences pain. What is the most likely cause?
- A. Inflammation of the vessels
- B. Obstructed blood flow
- C. Overhydration
- D. Stress-related headaches
Correct Answer: B
Rationale: In sickle cell anemia, pain is primarily caused by the obstruction of blood flow by sickle-shaped cells. This obstruction leads to inadequate oxygen supply to tissues, resulting in tissue damage and pain. Choice A, inflammation of the vessels, is incorrect as it is not the primary cause of pain in sickle cell anemia. Choice C, overhydration, is unrelated to the pathophysiology of sickle cell anemia and would not lead to the characteristic pain experienced. Choice D, stress-related headaches, is also unrelated to the underlying mechanisms of pain in sickle cell anemia.
What is the primary symptom of a urinary tract infection in young children?
- A. Frequent urination
- B. Abdominal pain
- C. Vomiting
- D. Fever
Correct Answer: D
Rationale: The correct answer is D, Fever. In young children, fever is a common primary symptom of a urinary tract infection, often accompanied by irritability and discomfort. Frequent urination (Choice A) is a symptom more commonly seen in adults with UTIs. While abdominal pain (Choice B) and vomiting (Choice C) can be present, they are not as primary as fever in young children with UTIs.
Why is randomization important in a scientific experiment?
- A. To minimize the impact of confounding variables.
- B. To eliminate bias in the assignment of subjects to groups.
- C. To contribute to the accuracy and validity of the experiment's results.
- D. To prevent systematic differences between groups.
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.
What is a common sign of congenital hip dysplasia in infants?
- A. Symmetrical hip movement
- B. Limited range of motion in the hip
- C. Swelling of the knees
- D. Dislocated patella
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.
What is a causative factor of Hirschsprung disease?
- A. Frequent evacuation of solids, liquids, and gases
- B. Excessive peristaltic movement
- C. Absence of parasympathetic ganglion cells in a portion of the colon
- D. One portion of the bowel telescoping into another
Correct Answer: C
Rationale: The correct answer is C: Absence of parasympathetic ganglion cells in a portion of the colon. Hirschsprung disease is a congenital condition characterized by the absence of nerve cells (ganglia) in parts of the colon. This absence leads to a lack of peristalsis in the affected segment, resulting in severe constipation and bowel obstruction. Choices A, B, and D are incorrect. Choice A describes symptoms of diarrhea rather than a causative factor of Hirschsprung disease. Excessive peristaltic movement (choice B) is not a causative factor but rather the opposite, as Hirschsprung disease is associated with reduced peristalsis. Choice D, which refers to intussusception, is a different condition unrelated to Hirschsprung disease.