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. Jill bears the genetic code for Von Willebrand disease, but she has never developed the illness herself. Jill would be considered:

• A. a carrier of the recessive gene that causes the disease.
• B. susceptible to the disease after adolescence.
• C. an acceptor of the recessive gene that causes the disease.
• D. susceptible to the disease in late adulthood.

Correct answer: A

Rationale: Jill is a carrier of the recessive gene for Von Willebrand disease. Being a carrier means that she has one copy of the gene but does not show symptoms of the disease. Carriers can pass on the gene to their offspring. Choice B is incorrect as being a carrier does not mean she is susceptible to developing the disease after adolescence. Choice C is incorrect as 'acceptor' is not a term used in genetics in this context. Choice D is incorrect as susceptibility to the disease is not related to late adulthood in carriers of a recessive gene.

3. Which of the following is a sexually transmitted infection that, in advanced stages, can attack major organ systems?

• A. Rubella
• B. Syphilis
• C. Cystic fibrosis
• D. Phenylketonuria

Correct answer: B

Rationale: Syphilis is the correct answer. Syphilis is a sexually transmitted infection caused by the bacterium Treponema pallidum. If left untreated, it can progress through various stages and potentially attack major organ systems, causing severe complications. Rubella, Cystic fibrosis, and Phenylketonuria are not sexually transmitted infections. Rubella is a viral infection, Cystic fibrosis is a genetic disorder affecting the lungs and digestive system, and Phenylketonuria is a genetic metabolic disorder. These conditions do not typically affect major organ systems in the same way as untreated syphilis.

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. Before meiosis, a sperm cell:

• A. contains 46 chromosomes.
• B. contains two X chromosomes.
• C. is significantly larger than an egg cell.
• D. contains both an X and a Y chromosome.

Correct answer: A

Rationale: Before meiosis, a sperm cell contains 46 chromosomes. This is because sperm cells, like other somatic cells, have a diploid number of chromosomes. During meiosis, the number of chromosomes is halved to 23 to combine with an egg cell during fertilization. Choice B is incorrect because a sperm cell carries either an X or a Y chromosome, not both (Choice D). Choice C is incorrect as sperm cells are generally smaller than egg cells, which is an adaptation that aids in motility and penetration of the egg during fertilization.

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