The distal portion of the male urethra ________. that runs the length of the penis is the epididymis, ductus (vas) ________.

Correct Answer: D

Rationale: The correct answer is D because the question is referring to the male urethra, not the epididymis or vas deferens. The distal portion of the male urethra that runs the length of the penis is the membranous urethra and the spongy (penile) urethra. A and B are incorrect as they mention the prostatic urethra, which is not the distal portion that runs the length of the penis. Choice C is incorrect as it only mentions the membranous urethra and does not address the full distal portion.

Correct Answer: A

Rationale: The correct answer is A because luteinising hormone (LH) and follicle stimulating hormone (FSH) are not secreted by the hypothalamus, but by the anterior pituitary gland. LH stimulates Leydig cells to produce testosterone, not the hypothalamus. Testosterone stimulates sertoli cells, not the other way around. Inhibin is indeed secreted by sertoli cells, but it does not relate to the incorrect statement regarding the origin of LH and FSH.

Correct Answer: D

Rationale: The correct answer is D because Sertoli cells do secrete inhibin, but it does not inhibit luteinizing hormone secretion. Inhibin actually inhibits follicle-stimulating hormone (FSH) secretion. Sertoli cells support spermatogenesis by nourishing developing sperm (A), they are stimulated by testosterone (B), and they also phagocytose defective sperm (C). Therefore, option D is incorrect as it misrepresents the role of inhibin in the endocrine regulation of the male reproductive system.

Correct Answer: B

Rationale: The correct answer is B: Ovum. The ovum is the mature female sex cell that unites with a male sperm during fertilization to form a zygote. Ovary (A) is the organ that produces eggs but is not the actual female sex cell. Gonad (C) is a general term for reproductive organs, not the specific female sex cell. Gametes (D) refer to both male and female sex cells, so it is a broad term and not the specific female sex cell. The ovum is the only choice that accurately represents the tiny female sex cell involved in fertilization.

Correct Answer: B

Rationale: The correct answer is B: ovaries. Ovaries are the organs responsible for producing, storing, and releasing human eggs. They are oval-shaped and play a crucial role in the female reproductive system. The other choices are incorrect because: A: clitoris is a small, sensitive organ located near the entrance of the vagina, not involved in egg production. C: Fallopian tubes are responsible for transporting eggs from the ovaries to the uterus, not for producing or storing eggs. D: Vagina is the muscular tube connecting the uterus to the outside of the body, not involved in egg production.