Nursing Elites

1. Which of the following illnesses causes degeneration of the central nervous system?

• A. Tay-Sachs disease
• B. Cystic fibrosis
• C. Turner syndrome
• D. Klinefelter syndrome

Correct answer: A

Rationale: Tay-Sachs disease is a genetic disorder that causes a progressive degeneration of the central nervous system, particularly in infants. Choice B, Cystic fibrosis, is a genetic disorder that primarily affects the lungs and digestive system, not the central nervous system. Choices C and D, Turner syndrome and Klinefelter syndrome, are chromosomal disorders that do not directly involve degeneration of the central nervous system.

2. 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.

3. In the context of an average ejaculation, which of the following statements is true about sperm?

• A. The average count of sperm in the ejaculate is 2.5 billion.
• B. Sperm in the ejaculate find the ovum by following the current of the fluid coming from the cervix.
• C. Only 1 in 1,000 sperm in the ejaculate will ever approach an ovum.
• D. Most of the sperm in the ejaculate move about in a random pattern in the vagina.

Correct answer: C

Rationale: Out of millions of sperm released during ejaculation, only a small fraction, about 1 in 1,000, will approach the ovum. This statement is true as sperm face many obstacles and challenges on their journey to reach and fertilize an ovum. Choice A is incorrect because the average count of sperm in an ejaculate is typically in the millions, not billions. Choice B is incorrect as sperm do not find the ovum by following the current of fluid; they navigate using other mechanisms. Choice D is incorrect because while some sperm may move randomly in the vagina, the ones that approach the ovum do so through a more purposeful and directed movement.

4. Thalidomide was marketed in the 1960s as a treatment for:

• A. insomnia and nausea.
• B. infertility and impotence.
• C. Down syndrome.
• D. Turner syndrome.

Correct answer: A

Rationale: Thalidomide was initially marketed as a treatment for insomnia and nausea, particularly in pregnant women. However, it was later found to cause severe birth defects, leading to significant consequences. Choice B, infertility and impotence, is incorrect as thalidomide was not marketed for these conditions. Choices C and D, Down syndrome and Turner syndrome, are genetic conditions and not conditions for which thalidomide was intended as a treatment.

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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