Sperm are formed in tightly coiled tubes called seminiferous tubules that are found within each ________.

Correct Answer: B

Rationale: The correct answer is B: testis. The seminiferous tubules are located within the testes, where sperm are produced through the process of spermatogenesis. The spermatic cord (A) contains blood vessels, nerves, and the vas deferens but not the seminiferous tubules. The ductus deferens (C) is a tube that carries sperm from the epididymis to the urethra, not where sperm are formed. The epididymis (D) is where sperm mature and are stored but not where they are initially formed. Therefore, the testis is the only choice where the seminiferous tubules are located for sperm production.

Correct Answer: C

Rationale: The correct answer is C: 120 days. Spermatogenesis is the process of sperm production, which involves several stages including mitosis, meiosis, and maturation. It takes around 64 days for the sperm to develop from spermatogonia to mature spermatozoa in the seminiferous tubules. After that, the sperm undergo additional maturation in the epididymis for approximately 12-14 days. Therefore, the entire process of spermatogenesis, from the initial division of spermatogonia to the release of mature sperm, takes approximately 120 days. Choice A (25-50 days) is too short for the complete process of spermatogenesis. Choice B (64-72 days) only covers the time for sperm development in the seminiferous tubules but does not include the maturation period in the epididymis. Choice D (1 year) is too long for spermatogenesis and does not accurately represent the

Correct Answer: A

Rationale: Estrogens stimulate growth of the endometrium during the proliferative phase by promoting cell proliferation and thickening of the endometrial lining. Estrogens also increase blood flow to the endometrium. Progesterone, on the other hand, prepares the endometrium for implantation and supports pregnancy, but does not directly stimulate growth during the proliferative phase. Insulin and testosterone do not have direct roles in stimulating endometrial growth during this phase.

Correct Answer: A

Rationale: The correct answer is A: bulbo-urethral glands. These glands produce a thick, yellowish secretion known as pre-ejaculate or Cowper's fluid. It serves to nourish and activate sperm. The other choices are incorrect because: B: The prostate gland produces a milky fluid that helps with sperm motility. C: The seminal glands (vesicles) produce a fluid that provides energy for sperm. D: The ejaculatory duct is a passageway for semen to leave the body, it does not produce any secretions.

Correct Answer: B

Rationale: The correct answer is B: bulbo-urethral glands. These glands secrete a milky-colored fluid called pre-ejaculate or Cowper's fluid, which lubricates the urethra and neutralizes any acidic urine residue to protect sperm. The other choices are incorrect because the epididymis (A) stores and matures sperm, the prostate (D) secretes a milky fluid that nourishes and protects sperm, and option C is incomplete.