Nursing Elites

1. Is Duchenne muscular dystrophy a sex-linked abnormality?

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

Correct answer: A

Rationale: The correct answer is A: TRUE. Duchenne muscular dystrophy is an X-linked recessive disorder, primarily affecting males. This is due to the inheritance of the mutated gene on the X chromosome. Choices B, C, and D are incorrect because Duchenne muscular dystrophy is specifically classified as a sex-linked disorder affecting males due to the inheritance pattern.

2. Monozygotic (MZ) twins share _________ percent of their genes.

• A. 100
• B. 75
• C. 50
• D. 25

Correct answer: A

Rationale: Monozygotic (MZ) twins share 100% of their genes because they originate from the same fertilized egg that splits into two, resulting in identical genetic material for both twins. Choice B (75%) is incorrect as it implies a partial genetic similarity, which is not the case for MZ twins. Choice C (50%) is incorrect as it suggests half of the genes are shared, which is applicable to dizygotic (DZ) twins, not MZ. Choice D (25%) is incorrect as it indicates minimal genetic sharing, which is not true for MZ twins.

3. When children who are reared by adoptive parents are nonetheless more similar to their natural parents in a trait, it can be concluded that:

• A. the genetic characteristics of the children change over time.
• B. heredity is solely responsible for how a child grows.
• C. the environment is solely responsible for the development of those characteristics.
• D. genetics play a role in the development of those characteristics.

Correct answer: D

Rationale: When children exhibit traits that are more similar to their biological parents than their adoptive parents, it indicates a strong genetic influence on those traits. This similarity suggests that genetics play a significant role in the development of the observed characteristics. Choice A is incorrect because genetic characteristics do not change over time in this context. Choice B is incorrect as it implies that heredity is the only factor, disregarding the impact of the environment. Choice C is also incorrect as it suggests that only the environment influences trait development, overlooking the genetic contribution.

4. Which of the following statements about Rh incompatibility is true?

• A. Rh incompatibility occurs most commonly during a woman’s first pregnancy.
• B. Rh incompatibility is an untreatable condition that leaves a woman infertile for the rest of her life.
• C. Rh incompatibility is an abnormality that is transmitted from generation to generation and carried by a sex chromosome.
• D. Rh incompatibility occurs due to antibodies transmitted to a fetus during subsequent deliveries causing brain damage or death.

Correct answer: D

Rationale: Rh incompatibility occurs when the mother's antibodies attack the fetus's red blood cells, leading to serious complications, usually in subsequent pregnancies. Choice A is incorrect because Rh incompatibility often occurs in subsequent pregnancies, not necessarily the first one. Choice B is incorrect as Rh incompatibility does not render a woman infertile but can lead to complications during pregnancies. Choice C is incorrect as Rh incompatibility is not carried by a sex chromosome but involves the Rh factor on red blood cells.

5. When both alleles' effects are shown, there is said to be:

• A. codominance.
• B. preponderance.
• C. ascendance.
• D. concurrence.

Correct answer: A

Rationale: The correct answer is A: codominance. Codominance refers to a genetic scenario where both alleles in a gene pair are fully expressed, leading to a phenotype that displays traits from both alleles equally. This is distinct from incomplete dominance where the traits blend. Choices B, C, and D are incorrect. Preponderance does not specifically relate to the expression of alleles. Ascendance and concurrence do not describe the genetic concept of codominance where both alleles are fully expressed.

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