Nursing Elites

1. What causes Down's syndrome?

• A. Alcohol abuse by the mother at the time of conception.
• B. Sex-linked chromosomal abnormalities.
• C. An extra chromosome on the 21st pair.
• D. Drug abuse by the mother during pregnancy.

Correct answer: C

Rationale: Down's syndrome, also known as trisomy 21, is caused by the presence of an extra chromosome on the 21st pair. Choice A is incorrect as alcohol abuse is not the cause of Down's syndrome. Choice B is incorrect because Down's syndrome is not related to sex-linked chromosomal abnormalities. Choice D is also incorrect as drug abuse by the mother during pregnancy is not the cause of Down's syndrome.

2. Which of the following pairs share 100% of their genes?

• A. Biovular twins
• B. Fraternal twins
• C. Dizygotic (DZ) twins
• D. Monozygotic (MZ) twins

Correct answer: D

Rationale: The correct answer is Monozygotic (MZ) twins. Monozygotic twins, also known as identical twins, share 100% of their genes because they originate from the same fertilized egg that splits into two. Fraternal twins (choice B), also known as dizygotic (DZ) twins (choice C), result from two separate fertilized eggs and share approximately 50% of their genes. Biovular twins (choice A) is not a term used in genetics and does not describe a type of twinning.

3. Which of the following statements is true of sickle-cell anemia?

• A. It is typically managed with treatments such as pain relief medications.
• B. It is caused by a mutation in the beta-globin gene.
• C. It leads to the obstruction of small blood vessels and decreased oxygen delivery.
• D. It is more prevalent in individuals of African, Mediterranean, Middle Eastern, and Indian descent.

Correct answer: C

Rationale: The correct answer is C. Sickle-cell anemia results from a mutation in the beta-globin gene, causing red blood cells to become sickle-shaped. These misshapen cells can obstruct small blood vessels, leading to reduced oxygen delivery to tissues. Choices A, B, and D are incorrect because sickle-cell anemia is typically managed with treatments such as pain relief medications, hydration, and in severe cases, blood transfusions. It is caused by a specific mutation in the beta-globin gene, not by the inability to metabolize phenylalanine. Additionally, sickle-cell anemia is more prevalent in individuals of African, Mediterranean, Middle Eastern, and Indian descent, not exclusive to any specific gender.

4. Which of the following is most likely to develop sickle cell anemia?

• A. European American
• B. Native American
• C. African American
• D. Asian American

Correct answer: C

Rationale: Sickle cell anemia is most commonly found in individuals of African American descent. This is because sickle cell trait provides some protection against malaria, and historically, regions where malaria is or was prevalent have higher rates of sickle cell anemia. Therefore, individuals with African ancestry are at a higher risk of developing sickle cell anemia compared to other populations. Choices A, B, and D are less likely to develop sickle cell anemia due to lower genetic prevalence in their respective populations.

5. What determines a child’s sex?

• A. Presence of teratogens at the time of conception.
• B. Sex chromosome received from the mother.
• C. Presence of teratogens at the time of ovulation.
• D. Sex chromosome received from the father.

Correct answer: D

Rationale: The correct answer is the sex chromosome received from the father. The father contributes either an X or Y chromosome, which determines the child's sex. This occurs at the moment of fertilization when the sperm carrying either an X (resulting in a female) or Y (resulting in a male) chromosome fertilizes the egg. Choices A, B, and C are incorrect because the presence of teratogens at the time of conception or ovulation does not determine the child's sex. While the sex chromosome received from the mother is important, it is the father's contribution that ultimately determines the child's sex.

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