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

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.

Correct Answer: B

Rationale: During the transition phase of labor, a client may experience intense back pain due to the pressure of the baby descending. Applying counterpressure to the client's sacrum can help alleviate this discomfort. Effleurage is a light stroking massage technique that may not provide adequate relief for intense back pain. Patterned-paced breathing is beneficial for managing contractions but may not directly address back pain. Biofeedback is a technique that helps individuals gain awareness and control of certain physiological functions, but it may not be the most appropriate intervention for acute labor pain.

Correct Answer: C

Rationale: Thalidomide is the correct answer. Thalidomide was a drug marketed in the 1960s to pregnant women as a sedative and anti-nausea medication but tragically led to severe birth defects, including limb deformities, when taken during pregnancy. Progestin (Choice A) and Estrogen (Choice B) are hormones that are not associated with causing birth defects like Thalidomide. Oxytocin (Choice D) is a hormone that plays a role in labor and breastfeeding and is not known to cause birth defects like Thalidomide.

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.