Concerning Muller’s cells, all are true except:

Correct Answer: B

Rationale: B: They are nerve cells. Rationale: Muller's cells are a type of glial cell in the retina, not nerve cells. They provide structural support and play a role in maintaining the retinal environment. Other choices are true: A) They form limiting membranes, C) They have long processes, and D) Their nuclei are in the inner nuclear layer.

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.

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.