Which hormone stimulates the male testes to produce sperm and stimulates the development of the follicle in the female on a monthly cycle.

Correct Answer: C

Rationale: Follicle-stimulating hormone (FSH) from the anterior pituitary stimulates spermatogenesis in male testes' Sertoli cells and follicle growth in female ovaries monthly, driving gamete production. Luteinizing hormone (LH) triggers testosterone in males and ovulation/oestradiol in females, not sperm/follicle initiation. Somatostatin inhibits hormone release (e.g., GH), not stimulating reproduction. Thymosin, from the thymus, boosts immunity, not gonadal function. FSH's dual reproductive role distinguishes it, key to fertility, unlike ovulation, inhibition, or immune hormones.

Correct Answer: D

Rationale: The thyroid gland sits at the throat's base, below the Adam's apple, secreting T3/T4 for metabolism and calcitonin for calcium. The pituitary, at the brain's base, controls other glands. The pineal, in the brain's midline, releases melatonin. The hypothalamus, above the pituitary, regulates it, not at the throat. Thyroid's neck location and metabolic role distinguish it, key to its anatomical and functional identity, unlike brain-based glands.

Correct Answer: C

Rationale: The pancreas is both endocrine (islets secrete insulin/glucagon into blood) and exocrine (acini release digestive enzymes via ducts). Thyroid (T3/T4) and thymus (thymosin) are purely endocrine, lacking ducts. Pituitary (e.g., GH) is endocrine-only, no exocrine function. Pancreas' dual role distinguishes it, essential for metabolic and digestive integration, unlike single-function glands.

Correct Answer: A

Rationale: Glucagon accelerates glycogenolysis, converting liver glycogen to glucose to raise blood levels, countering insulin. Slowing gluconeogenesis (glucose from lactic acid) opposes glucagon's role it promotes it. Decreasing glycogen conversion is insulin's job. Protein synthesis isn't glucagon-driven GH or insulin-like factors handle that. Glycogenolysis acceleration distinguishes glucagon, key to fasting glucose supply, unlike inhibitory or anabolic actions.

Correct Answer: A

Rationale: The parathyroid glands secrete PTH to raise blood calcium via bone resorption and kidney reabsorption, while the thyroid's calcitonin lowers it by inhibiting resorption. Adrenal medulla (catecholamines), pancreas (insulin), testes (testosterone), and thymus (immunity) don't regulate calcium. Parathyroid-thyroid balance distinguishes this control, key to skeletal and metabolic homeostasis.