In the following figure, which lines most likely reflect the responses in a patient with nephrogenic diabetes insipidus?

Correct Answer: B

Rationale: The correct answer is B because in nephrogenic diabetes insipidus, the kidney tubules are unable to respond to antidiuretic hormone (ADH). This results in the inability to concentrate urine, leading to excessive dilute urine output. Lines A and D in the figure represent a high urine output (polyuria) and low urine osmolality, which are characteristic of nephrogenic diabetes insipidus. Choice A (A and C) is incorrect because line C does not show low urine osmolality. Choice C (B and C) is incorrect because line B does not show high urine output. Choice D (B and D) is incorrect because line D does not show low urine osmolality.

Correct Answer: D

Rationale: The correct answer is D: Abnormally high levels of testosterone in the maternal blood. This can cause virilization of the female fetus, leading to the development of male external genitalia. Testosterone exposure during fetal development can result in the formation of a penis and scrotum without testes in a genetic female (XX). Rationale: 1. Testosterone is responsible for the development of male external genitalia. 2. XX chromosomes indicate a genetic female. 3. Lack of testes indicates incomplete masculinization. 4. High levels of testosterone can override the default female development pattern. Other choices are incorrect because: A: Human chorionic gonadotropin does not directly affect fetal genital development. B: Estrogen is not responsible for male genital development. C: Luteinizing hormone does not directly influence the development of external genitalia in the fetus.

Correct Answer: D

Rationale: Step 1: The trophoblast cells of the blastocyst invade the endometrial lining during implantation. Step 2: The trophoblast cells secrete enzymes to digest the nutrient-rich endometrial cells. Step 3: The digested nutrients are absorbed by the trophoblast cells. Step 4: These nutrients are then utilized by the blastocyst for its growth and development. Step 5: This process ensures that the blastocyst receives the necessary nutrition for the first week after implantation. Summary: A: Incorrect. Endometrial secretions are no longer the source of nutrition after implantation. B: Incorrect. While the blastocyst may contain some stored nutrients, they are not sufficient for the first week post-implantation. C: Incorrect. The placenta is not fully functional until later in pregnancy, so it does not provide nutrition in the first week.

Correct Answer: B

Rationale: The correct answer is B, after ovulation in a female. After ovulation, the ruptured follicle transforms into a corpus luteum, which secretes progesterone to support the uterine lining. Prior to ovulation (choice A) there is a mature follicle, not a corpus luteum. Choice C is incorrect as the corpus luteum is a structure in the female reproductive system, not present in semen. Choice D is incorrect as the corpus luteum persists for about 14 days after ovulation, not just on the day of ovulation.

Correct Answer: C

Rationale: The correct answer is C: Head. The head of the sperm contains the nucleus, which houses the DNA. The nucleus carries the genetic information required for fertilization. The midpiece contains mitochondria for energy production, the flagellum provides motility, and the tail is a part of the flagellum. Therefore, the head is the only part of the sperm that houses the nucleus and DNA, making it the correct answer.