Testosterone

Correct Answer: D

Rationale: Step-by-step rationale for why D is correct: 1. Testosterone is a key hormone for muscle growth. 2. It stimulates protein synthesis in muscles. 3. This leads to an increase in skeletal muscle size and mass. 4. Therefore, the correct answer is D. Summary: A: Testosterone does not directly boost basal metabolic rate. B: Testosterone can influence behavior, but this is not the primary function discussed in the question. C: Testosterone does not directly increase bone density.

Correct Answer: D

Rationale: The correct answer is D: interstitial cells. Interstitial cells, also known as Leydig cells, are located in the testes and are responsible for producing male sex hormones, primarily testosterone. The other choices, A: epididymis, B: vas deferens, and C: seminiferous tubules, are not directly involved in the production of male sex hormones. The epididymis is a structure for sperm maturation, the vas deferens is a duct for transporting sperm, and the seminiferous tubules are responsible for sperm production through spermatogenesis. Therefore, interstitial cells are the source of male sex hormones, making choice D the correct answer.

Correct Answer: C

Rationale: The correct answer is C: corpora spongiosum. The urethra passes through the corpora spongiosum of the penis, which is a spongy tissue that surrounds the urethra. This allows for the passage of urine and semen during ejaculation. The other choices are incorrect because: A) The tunica albuginea is a fibrous covering of the corpora cavernosa, not the urethra. B) The prepuce is the foreskin that covers the glans penis, not part of the urethra. D) The corpora cavernosa are erectile tissue responsible for penile erection, not part of the urethra's pathway.

Correct Answer: A

Rationale: The correct answer is A: Graafian follicle. The mature follicle is called a Graafian follicle because it is the final stage of follicle development before ovulation. It is characterized by a fluid-filled cavity containing the oocyte. The other choices are incorrect because a granulosa cell is a type of cell found in the follicle wall, a primary follicle is an immature follicle, and a secondary follicle is an intermediate stage between the primary and Graafian follicle.

Correct Answer: C

Rationale: The correct answer is C: estrogen. Estrogen is a type of steroid hormone derived from cholesterol. Steroids are a specific group of lipids characterized by a particular molecular structure. Estrogen plays a vital role in the development and regulation of the female reproductive system. Choice A, FSH, and choice B, LH, are both peptide hormones, not steroids. Peptide hormones are made up of amino acids and are not derived from cholesterol. Choice D, GnRH, is also a peptide hormone that regulates the release of other hormones in the body, particularly in the reproductive system. In summary, estrogen is the only steroid hormone among the options provided, making it the correct choice.