In the structure of deoxyribonucleic acid (DNA), which of the following bases combines with thymine?

Correct Answer: B

Rationale: The correct answer is B: Adenine. In the structure of DNA, adenine pairs with thymine through hydrogen bonding, forming one of the complementary base pairs that make up the double helix structure of DNA. Cytosine pairs with guanine, not thymine. Rhodamine and serine are not DNA bases and do not participate in DNA base pairing. Therefore, choices A, C, and D are incorrect.

Correct Answer: D

Rationale: Rh incompatibility occurs when the mother's antibodies attack the fetus's red blood cells, leading to serious complications, usually in subsequent pregnancies. Choice A is incorrect because Rh incompatibility often occurs in subsequent pregnancies, not necessarily the first one. Choice B is incorrect as Rh incompatibility does not render a woman infertile but can lead to complications during pregnancies. Choice C is incorrect as Rh incompatibility is not carried by a sex chromosome but involves the Rh factor on red blood cells.

Correct Answer: D

Rationale: Huntington's disease is a fatal genetic neurologic disorder characterized by progressive nerve cell degeneration in the brain. It typically manifests in middle age with symptoms such as involuntary movements, cognitive decline, and psychiatric disturbances. Tay-Sachs disease (Choice A) is a genetic disorder that primarily affects the nervous system in early childhood, not middle age. Duchenne muscular dystrophy (Choice B) is a genetic disorder that primarily affects muscle function and usually presents in early childhood. Hemophilia (Choice C) is a genetic disorder related to blood clotting, and its onset is not typically in middle age.

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.

Correct Answer: A

Rationale: The correct answer is A: TRUE. Advanced parental age, particularly maternal age, is associated with an increased risk of Down's syndrome in offspring. As parents get older, the likelihood of having a child with Down's syndrome increases. Choices B, C, and D are incorrect because the risk of Down's syndrome is known to rise with parental age, especially maternal age, due to the increased likelihood of chromosomal abnormalities during egg formation.

Correct Answer: D

Rationale: An amniocentesis in this scenario is most likely being performed to assess fetal lung maturity. This is necessary when considering early delivery due to macrosomia (large fetal size), which is a common concern in gestational diabetes. Evaluating fetal lung maturity is crucial to determine if the fetus's lungs are developed enough to support breathing independently outside the womb. The presence of a neural tube defect and chromosomal abnormalities are not typically assessed through amniocentesis in this situation, and determining the gender of the fetus is not the primary purpose of the procedure here.

Correct Answer: D

Rationale: During the transitional phase of labor, which is the most intense phase, the primary focus of nursing care for a client who anticipates an unmedicated delivery should be assisting her to maintain control. This is essential to help her manage the intense pain and anxiety associated with this phase without the use of medication. Assessing the strength of uterine contractions (Choice A) is important but not the primary focus during the transitional phase. Re-evaluating the need for medication (Choice B) is not applicable as the client anticipates an unmedicated delivery. Reminding her to push 3 times with each contraction (Choice C) is more related to the pushing stage of labor and not the transitional phase.

Correct Answer: C

Rationale: The correct answer is 'Motility.' Motility refers to the ability of cells or organisms to move by themselves, often through the use of specialized structures like flagella or cilia. Mitosis (Choice A) and Meiosis (Choice B) are processes related to cell division and genetic recombination, respectively, not self-propulsion. Mutation (Choice D) refers to changes in the DNA sequence and is not related to self-propulsion.

Correct Answer: B

Rationale: Preconception counseling is essential as strict metabolic control before conception and in the early weeks of gestation helps reduce the risk of congenital anomalies. Frequent episodes of maternal hypoglycemia usually occur during the first trimester due to hormonal changes, affecting insulin production and use, rather than before conception. Hydramnios is more common in diabetic pregnancies, typically seen in the third trimester, not during early pregnancy. Hyperemesis gravidarum, although it may lead to hypoglycemic events, is related to decreased food intake and glucose transfer to the fetus, exacerbating hypoglycemia rather than being directly associated with poor glycemic control before and during early pregnancy.