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. How many chromosomes are typically found in human cells, organized into pairs?

• A. 50
• B. 46
• C. 48
• D. 44

Correct answer: B

Rationale: Human cells typically contain 46 chromosomes organized into 23 pairs. This is the correct number for a normal human cell. Choices A, C, and D are incorrect because they do not represent the typical chromosome count in human cells.

3. Which of the following conditions is considered a multifactorial problem?

• A. Cystic fibrosis
• B. Down syndrome
• C. Diabetes mellitus
• D. XYY syndrome

Correct answer: C

Rationale: The correct answer is 'Diabetes mellitus' because it is a multifactorial disease, influenced by both genetic predisposition and environmental factors. Cystic fibrosis (choice A) is primarily a genetic disorder caused by mutations in the CFTR gene. Down syndrome (choice B) is due to an extra copy of chromosome 21. XYY syndrome (choice D) is a genetic condition where males have an extra Y chromosome. These conditions are not considered multifactorial as their origins are primarily genetic.

4. If an individual receives a recessive gene for eye color from both parents, the:

• A. gender of the child will not determine the expression of that trait.
• B. recessive trait will be expressed in the child.
• C. recessive trait will be expressed in all the offspring.
• D. recessive trait will be suppressed, and the dominant trait will not be expressed.

Correct answer: B

Rationale: When an individual inherits a recessive gene for eye color from both parents, the recessive trait will be expressed in the child. This is because having two copies of the recessive gene overrides the presence of any dominant gene. Choice A is incorrect because the expression of the trait is determined by the genetic makeup, not the gender of the child. Choice C is incorrect as the expression of the recessive trait is certain when both parents pass on the recessive gene, but it does not mean that all offspring will express the trait. Choice D is incorrect because if both parents provide a recessive gene, the dominant trait will not be expressed in the child, but it does not mean it will be suppressed; rather, the recessive trait will be expressed.

5. 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.

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