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. What is the process in which the double helix of deoxyribonucleic acid (DNA) duplicates?

• A. Amniocentesis
• B. Mitosis
• C. Meiosis
• D. Mutation

Correct answer: B

Rationale: Mitosis is the correct answer because it is the process of cell division in which a cell duplicates its DNA and divides into two identical daughter cells. During mitosis, the DNA is replicated, and each daughter cell receives an identical copy of the genetic material. Amniocentesis is a medical procedure to collect amniotic fluid for prenatal genetic testing and is not related to DNA duplication. Meiosis is a type of cell division that produces gametes with half the genetic material of the parent cell, leading to genetic diversity. Mutation is a permanent alteration in the DNA sequence that can lead to genetic variations but is not the process of DNA duplication.

3. What is the central layer of the embryo from which the bones and muscles develop?

• A. neural tube
• B. mesoderm
• C. ectoderm
• D. umbilical cord

Correct answer: B

Rationale: The correct answer is mesoderm. The mesoderm is the middle layer of the embryo that gives rise to the bones, muscles, and other connective tissues. The neural tube (choice A) develops into the nervous system, not bones and muscles. The ectoderm (choice C) forms the skin and nervous system, not bones and muscles. The umbilical cord (choice D) is a structure that connects the developing fetus to the placenta; it is not a layer of the embryo that gives rise to bones and muscles.

4. Tim, a 27-year-old man, has unusually narrow shoulders, low muscle mass, and has no facial and body hair. His doctor recently prescribed testosterone replacement therapy to him. Tim is most likely suffering from:

• A. Phenylketonuria (PKU).
• B. Cystic fibrosis.
• C. Klinefelter syndrome.
• D. Huntington’s disease (HD).

Correct answer: C

Rationale: Tim's physical characteristics, such as narrow shoulders, low muscle mass, and lack of facial and body hair, are typical signs of Klinefelter syndrome, a genetic condition where males have an extra X chromosome (XXY). This leads to underdeveloped testes and reduced testosterone production, resulting in features like gynecomastia, sparse facial and body hair, and reduced muscle mass. Testosterone replacement therapy is commonly used to address the hormonal imbalance in individuals with Klinefelter syndrome. Phenylketonuria (PKU) is a metabolic disorder unrelated to the symptoms described in Tim's case. Cystic fibrosis is a genetic respiratory condition that does not present with the physical characteristics mentioned. Huntington’s disease (HD) is a neurodegenerative disorder primarily affecting motor function and cognition, not physical appearance and muscle mass.

5. Does a blastocyst gain mass only when it receives nourishment from outside?

• A. TRUE
• B. FALSE
• C. Sometimes
• D. Always

Correct answer: A

Rationale: A blastocyst does indeed require external nourishment from the mother's body to continue developing and gaining mass. Without this external nourishment, the blastocyst would not be able to grow and develop properly. Therefore, the statement that a blastocyst gains mass only when it receives nourishment from outside is true. Choices B, C, and D are incorrect because they do not accurately reflect the dependency of a blastocyst on external nourishment for its development and growth.

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