What normally inhibits testosterone production?

Correct Answer: B

Rationale: The correct answer is B because increasing ICSH (Luteinizing Hormone) inhibits testosterone production by exerting negative feedback on the testes. ICSH stimulates Leydig cells in the testes to produce testosterone. When testosterone levels rise, it signals the pituitary gland to decrease ICSH secretion, thus inhibiting further testosterone production. A: Increasing FSH (Follicle-Stimulating Hormone) does not inhibit testosterone production. C: Decreasing ICSH would lead to reduced stimulation of Leydig cells and lower testosterone production. D: Decreasing FSH would not directly inhibit testosterone production as FSH primarily stimulates sperm production in the testes.

Correct Answer: B

Rationale: The correct answer is B: estrogen. Estrogen is produced throughout the menstrual cycle by the ovaries. It plays a key role in regulating the menstrual cycle, promoting the growth of the uterine lining, and preparing the body for ovulation. FSH and LH are involved in stimulating the ovaries to produce estrogen and progesterone, respectively. Progesterone is mainly produced in the second half of the menstrual cycle, after ovulation, to support pregnancy. Therefore, estrogen is the hormone that is produced consistently throughout the menstrual cycle, making it the correct answer.

Correct Answer: D

Rationale: The correct answer is D: oxytocin. Oxytocin is the hormone responsible for initiating and sustaining labor contractions by stimulating the uterine muscles. It acts on the smooth muscle cells of the uterus to increase contractions. Estrogen (A) plays a role in preparing the uterus for labor but doesn't initiate contractions. HCG (B) is a hormone produced during pregnancy but is not directly involved in labor. Relaxin (C) helps relax the pelvic ligaments to facilitate childbirth, but it doesn't initiate contractions.

Correct Answer: A

Rationale: The correct answer is A: Placenta. The placenta is a temporary organ that connects a mammalian mother to its foetus by facilitating the exchange of nutrients, gases, and waste products between the mother and the developing baby. It also produces hormones necessary for pregnancy. Explanation of other choices: B: Chorion - The chorion is a membrane that surrounds the embryo and contributes to the formation of the placenta, but it is not the organ that directly connects the mother to the foetus. C: Endometrium - The endometrium is the inner lining of the uterus where implantation of the fertilized egg occurs, but it is not the organ that connects the mother to the foetus. D: None of the above - This choice is incorrect as the placenta is indeed the temporary organ that serves as the connection between the mother and the foetus in mammalian reproduction.

Correct Answer: D

Rationale: The correct answer is D because the ovaries produce secondary oocytes, which are released during ovulation for fertilization. Additionally, the ovaries produce estrogen and progesterone, which are essential for the menstrual cycle and reproductive health. Choice A is incorrect as primary oocytes are present before birth and insulin is produced by the pancreas. Choice B is incorrect because cortisol is produced by the adrenal glands, not the ovaries. Choice C is incorrect as tertiary oocytes do not exist, and insulin is produced by the pancreas.