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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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A client at 26 weeks gestation was informed this morning that she has an elevated alpha-fetoprotein (AFP) level. After the healthcare provider leaves the room, the client asks what she should do next. What information should the nurse provide?
- A. Reassure the client that the AFP results are likely to be a false reading.
- B. Explain that a sonogram should be scheduled for definitive results.
- C. Inform her that a repeat alpha-fetoprotein (AFP) test should be evaluated.
- D. Discuss options for intrauterine surgical correction of congenital defects.
Correct Answer: B
Rationale: An elevated AFP level during pregnancy can indicate potential fetal anomalies. Further evaluation is necessary to confirm the findings and assess the need for additional interventions. Scheduling a sonogram is the appropriate next step as it can provide more definitive results and help identify any underlying issues. Choice A is incorrect because dismissing the elevated AFP level as a false reading without further investigation can lead to missing important information about the baby's health. Choice C is not the best immediate action, as scheduling a sonogram would provide more detailed information than just repeating the AFP test. Choice D is incorrect as discussing intrauterine surgical correction is premature at this stage and not typically indicated based solely on an elevated AFP level.
Which of the following statements is true of sickle-cell anemia?
- A. It is typically managed with treatments such as pain relief medications.
- B. It is caused by a mutation in the beta-globin gene.
- C. It leads to the obstruction of small blood vessels and decreased oxygen delivery.
- D. It is more prevalent in individuals of African, Mediterranean, Middle Eastern, and Indian descent.
Correct Answer: C
Rationale: The correct answer is C. Sickle-cell anemia results from a mutation in the beta-globin gene, causing red blood cells to become sickle-shaped. These misshapen cells can obstruct small blood vessels, leading to reduced oxygen delivery to tissues. Choices A, B, and D are incorrect because sickle-cell anemia is typically managed with treatments such as pain relief medications, hydration, and in severe cases, blood transfusions. It is caused by a specific mutation in the beta-globin gene, not by the inability to metabolize phenylalanine. Additionally, sickle-cell anemia is more prevalent in individuals of African, Mediterranean, Middle Eastern, and Indian descent, not exclusive to any specific gender.
According to a study conducted in 2013 by Fellman, what affects the chances of having twins?
- A. Increase when a woman conceives at a younger age.
- B. Increase with parental age.
- C. Decrease with the frequency of intercourse before conception.
- D. Decrease with the use of fertility drugs.
Correct Answer: B
Rationale: The correct answer is B. According to the study by Fellman in 2013, the chances of having twins actually increase with parental age. Choice A is incorrect as the study does not specify a younger age for conceiving to increase the chances of twins. Choice C is incorrect as the frequency of intercourse before conception is not a highlighted factor in the study. Choice D is also incorrect as the study does not discuss the impact of fertility drugs on the likelihood of having twins.
Chromosomes are _____ structures found in cells.
- A. rod-shaped
- B. circular
- C. cone-shaped
- D. octagonal
Correct Answer: A
Rationale: Chromosomes are rod-shaped structures that carry genetic information in the form of DNA. They are typically seen as elongated structures when visualized under a microscope. Choice B, circular, is incorrect as chromosomes do not have a circular shape; they are linear. Choice C, cone-shaped, is not accurate as chromosomes do not resemble cones in any way. Choice D, octagonal, is also incorrect as chromosomes do not have an octagonal appearance. Therefore, the correct answer is A, rod-shaped, which accurately describes the shape of chromosomes.
Which of the following pairs of bases is present in the rungs of the ladder-like structure of deoxyribonucleic acid (DNA)?
- A. Cytosine with guanine.
- B. Rhodamine with biotin.
- C. Diaminopurine with ribozyme.
- D. Serine with tyrosine.
Correct Answer: A
Rationale: The correct answer is A: Cytosine with guanine. In the DNA double helix, cytosine always pairs with guanine forming a base pair, and adenine pairs with thymine. These complementary base pairs form the rungs of the ladder-like structure of DNA. Choice B, Rhodamine with biotin, is incorrect as they are not base pairs found in DNA. Choice D, Serine with tyrosine, is incorrect as they are amino acids, not DNA bases. Choice C, Diaminopurine with ribozyme, is also incorrect as ribozyme is an enzyme, not a base, and diaminopurine is not one of the standard bases found in DNA.