A surge of FSH and LH is induced in the adenohypophysis 24 hours before ovulation and the first meiotic division of the primary oocyte resumes. At what stage does the oocyte become arrested until it becomes fertilized?

Correct Answer: D

Rationale: The correct answer is D: Second meiotic division, metaphase. After the surge of FSH and LH induces the first meiotic division to resume, the oocyte becomes arrested at the metaphase stage of the second meiotic division until fertilization. This arrest allows for the completion of meiosis upon fertilization. Choices A and B are incorrect because the oocyte does not become arrested at the prophase or metaphase of the first meiotic division. Choice C is incorrect because the oocyte does not become arrested at the prophase of the second meiotic division, but rather at the metaphase stage.

Correct Answer: B

Rationale: The correct answer is B: epididymis. Sperm maturation occurs in the epididymis, a coiled tube located on the posterior surface of the testes. Here, sperm undergo the process of capacitation, gaining the ability to fertilize an egg. The seminiferous tubules (choice A) are responsible for sperm production, not maturation. The vas deferens (choice C) is a duct that carries mature sperm from the epididymis to the urethra, and the urethra (choice D) is a passage for both urine and sperm but not the site of sperm maturation.

Correct Answer: B

Rationale: The correct answer is B: Inhibin. Inhibin is a hormone secreted by the testes in response to high levels of sperm production. Inhibin acts as a negative feedback signal to the pituitary gland, inhibiting the production of follicle-stimulating hormone (FSH). This helps to regulate spermatogenesis by preventing excessive FSH stimulation. A: Testosterone is not the negative feedback signal for inhibiting FSH production. While testosterone does play a role in regulating spermatogenesis, it does not directly inhibit pituitary FSH production. C: Estrogen is not involved in the negative feedback control system of spermatogenesis. Estrogen is more closely associated with the female reproductive system. D: Luteinizing hormone is not the negative feedback signal for inhibiting FSH production. LH is involved in the regulation of testosterone production, not FSH.

Correct Answer: A

Rationale: The correct answer is A: She has been receiving hormone replacement therapy with estrogen and progesterone since she completed menopause. Hormone replacement therapy suppresses the release of FSH by providing exogenous hormones, thereby reducing the body's need to produce FSH. This explains the low levels of FSH in her blood despite being postmenopausal. Explanation for why the other choices are incorrect: B: Her adrenal glands continue to produce estrogen - Adrenal glands do produce small amounts of estrogen, but not in sufficient quantities to significantly impact FSH levels. C: Her ovaries continue to secrete estrogen - Ovaries cease estrogen production after menopause, so this would not explain the low FSH levels. D: She took birth control pills for 20 years before menopause - Birth control pills do not directly impact FSH levels in postmenopausal women.

Correct Answer: B

Rationale: The correct answer is B: Rate of movement will decrease. Sperm cells require a slightly alkaline environment to maintain their motility. Lowering the pH to 4.5 will create an acidic environment, causing decreased sperm motility. Choice A is incorrect as lowering pH doesn't affect metabolic rate. Choice C is incorrect because prostaglandin E2 formation is not directly related to pH changes. Choice D is incorrect as oxygen consumption rate of sperm cells is not affected by vaginal pH.