Nokea
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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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.
What determines a child's sex?
- A. Presence of teratogens at the time of conception.
- B. Sex chromosome received from the mother.
- C. Presence of teratogens at the time of ovulation.
- D. Sex chromosome received from the father.
Correct Answer: D
Rationale: The correct answer is the sex chromosome received from the father. The father contributes either an X or Y chromosome, which determines the child's sex. This occurs at the moment of fertilization when the sperm carrying either an X (resulting in a female) or Y (resulting in a male) chromosome fertilizes the egg. Choices A, B, and C are incorrect because the presence of teratogens at the time of conception or ovulation does not determine the child's sex. While the sex chromosome received from the mother is important, it is the father's contribution that ultimately determines the child's sex.
A 38-week primigravida is admitted to labor and delivery after a non-reactive result on a non-stress test (NST). The nurse begins a contraction stress test (CST) with an oxytocin infusion. Which finding is most important for the nurse to report to the healthcare provider?
- A. A pattern of fetal late decelerations.
- B. Fetal heart rate accelerations with fetal movement.
- C. Absence of uterine contractions within 20 minutes.
- D. Spontaneous rupture of membranes.
Correct Answer: A
Rationale: The correct answer is A: A pattern of fetal late decelerations. Late decelerations during a contraction stress test are concerning as they indicate uteroplacental insufficiency, which can pose a risk to fetal well-being. Reporting this finding to the healthcare provider is crucial for prompt intervention. Choice B, fetal heart rate accelerations with fetal movement, is a reassuring sign of fetal well-being and does not raise immediate concerns. Choice C, absence of uterine contractions within 20 minutes, may require further assessment but is not as critical as late decelerations. Choice D, spontaneous rupture of membranes, is important but not the most immediate concern during a contraction stress test.
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.
What maternal factor should the nurse identify as having the greatest impact on the development of spina bifida occulta in a newborn?
- A. Short interval between pregnancies
- B. Folic acid deficiency
- C. Preeclampsia
- D. Tobacco use
Correct Answer: B
Rationale: Folic acid deficiency during pregnancy is a well-known risk factor for neural tube defects, including spina bifida occulta, making supplementation critical in prenatal care. Folic acid plays a crucial role in neural tube formation during early pregnancy. Short intervals between pregnancies do not directly impact the development of spina bifida occulta. Preeclampsia is a hypertensive disorder of pregnancy and is not directly linked to spina bifida occulta. While tobacco use during pregnancy has various adverse effects, it is not the primary factor influencing the development of spina bifida occulta in newborns.