Nursing Elites

1. When both of the alleles for a trait, such as hair color, are the same, the person is said to be _____ for that trait.

• A. monozygous
• B. dizygous
• C. homozygous
• D. hemizygous

Correct answer: C

Rationale: A person is homozygous for a trait when they have two identical alleles for that trait. In this case, both alleles are the same, indicating a homozygous genotype. Choice A, 'monozygous,' is incorrect as it refers to identical twins originating from a single fertilized egg. Choice B, 'dizygous,' is also incorrect as it refers to fraternal twins or individuals that develop from two separate fertilized eggs. Choice D, 'hemizygous,' is incorrect because it describes a genetic condition where only one allele is present in a diploid organism, typically related to genes on the sex chromosomes.

2. Which of the following statements is true of Down’s syndrome?

• A. Down’s syndrome is usually caused by an extra copy of chromosome 21 in an individual.
• B. The symptoms of Down’s syndrome are similar to those of sickle-cell anemia.
• C. Down’s syndrome is caused by a sexually transmitted infection (STI) during conception.
• D. The probability of having a child with Down’s syndrome increases with the age of the parents.

Correct answer: D

Rationale: The correct answer is D. The likelihood of having a child with Down’s syndrome increases as the age of the parents increases, particularly the mother's age. Choice A is incorrect because Down’s syndrome is caused by an extra copy of chromosome 21, not a defect in the sex chromosomes. Choice B is incorrect as the symptoms of Down’s syndrome and sickle-cell anemia are different. Choice C is also incorrect as Down’s syndrome is not caused by a sexually transmitted infection during conception.

3. Which of the following processes happen during mitosis?

• A. Strands of deoxyribonucleic acid (DNA) break apart.
• B. Adenine combines with its appropriate partner, cytosine.
• C. Sperm and ova cells are created.
• D. Twenty-three chromosomes are created.

Correct answer: A

Rationale: The correct process that happens during mitosis is the breaking apart, replication, and division of DNA strands into two new cells, each with the same number of chromosomes as the original cell. Choice B is incorrect because it describes base pairing in DNA, not a process specific to mitosis. Choice C is incorrect as the creation of sperm and ova cells is related to meiosis, not mitosis. Choice D is incorrect because chromosomes are not created during mitosis; they are replicated and divided equally between the daughter cells.

4. Dizygotic (DZ) twins share _________ percent of their genes.

• A. 100
• B. 75
• C. 50
• D. 25

Correct answer: C

Rationale: Dizygotic (DZ) twins share approximately 50% of their genes. This is because dizygotic twins, also known as fraternal twins, originate from two separate fertilized eggs and share similar genetic similarity to regular siblings. Choice A (100%) is incorrect because if twins shared 100% of their genes, they would be identical twins (monozygotic). Choice B (75%) is incorrect as it is not the typical genetic similarity seen in dizygotic twins. Choice D (25%) is incorrect as it represents a significantly lower genetic similarity than what is observed in dizygotic twins.

5. According to a study in 2014 by Skakkebaek et al., who among the following is most likely to have gynecomastia?

• A. Jennifer, a dancer, who has Down syndrome
• B. Frank, a teacher, who is diagnosed with XYY syndrome
• C. Peter, a fashion designer, who has Klinefelter syndrome
• D. Ria, a gym instructor, who is diagnosed with Turner syndrome

Correct answer: C

Rationale: Individuals with Klinefelter syndrome have an extra X chromosome (XXY) and typically have reduced testosterone levels, which can lead to gynecomastia (enlarged breasts). This condition is not usually associated with Down syndrome (choice A), XYY syndrome (choice B), or Turner syndrome (choice D), making them less likely to have gynecomastia.

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