Sperm maturation occurs in the

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: 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.

Correct Answer: C

Rationale: The correct answer is C: The placenta secretes estrogen. The placenta is an endocrine organ that produces hormones, including estrogen, which plays a crucial role in maintaining pregnancy. Estrogen helps in regulating the menstrual cycle, promoting fetal growth, and preparing the body for childbirth. Choices A and B are incorrect because the placenta does not develop from granulosa cells and does not secrete luteinizing hormone. Choice D is incorrect because the placenta does not allow direct mixing of maternal and fetal blood; instead, it facilitates the exchange of nutrients and waste products between the mother and the fetus through a barrier called the placental barrier.

Correct Answer: C

Rationale: The correct answer is C because semen does not contain enzymes that enhance sperm motility. Sperm motility is primarily influenced by the structure and health of the sperm themselves. Semen aids in sperm transport, provides nutrients, buffers the acidic vaginal environment, and contains antibiotics. Enzymes in semen primarily help with liquefaction of semen after ejaculation, not sperm motility. Choices A, B, and D are incorrect because semen does dilute sperm, neutralizes the acidic vaginal environment, and contains antibiotic chemicals, respectively.