Thyroid gland produces a hormone called 'thyroxine' which

Correct Answer: C

Rationale: Thyroxine (T4), produced by the thyroid gland, regulates the body's metabolic rate, dictating how cells convert nutrients into energy, impacting heart rate, digestion, and growth. Blood glucose is managed by insulin/glucagon from the pancreas, ovulation by LH/FSH from the pituitary neither thyroxine's role. 'More than one' is incorrect as thyroxine's primary function is singularly metabolic. This specificity distinguishes thyroxine's systemic metabolic influence, critical for energy homeostasis, contrasting with glucose or reproductive hormones.

Correct Answer: B

Rationale: Adrenal medulla secretes dopamine (minor), alongside epinephrine/norepinephrine, from chromaffin cells, aiding stress responses. Cortisol, primary glucocorticoid from zona fasciculata, isn't sole corticosterone exists, though less. Oestrogens (from zona reticularis) aren't largest molecular size varies, aldosterone similar. Cortisol has some mineralocorticoid activity (e.g., in excess like Cushing's), not negligible. Dopamine's medullary secretion distinguishes it, key to catecholamine diversity, unlike glucocorticoid exclusivity, size, or activity claims.

Correct Answer: D

Rationale: PTH increases urinary PO₄ excretion by inhibiting reabsorption, lowering serum PO₄ while raising Ca²⁺. Gastrin/glucagon/secretin don't notably inhibit calcitonin calcium does. Calcitonin's half-life is ~10 minutes, not 30. Calcitonin reduces bone resorption, not increases. PTH's phosphate effect distinguishes it, key to calcium-phosphate balance, unlike hormonal, kinetic, or resorption errors.

Correct Answer: D

Rationale: Oxytocin, from hypothalamus, is stored/released by posterior pituitary, not anterior lactation/childbirth role. ACTH (adrenal), prolactin (lactation), and β-lipoprotein (lipid metabolism, though less common term) are anterior pituitary hormones. Oxytocin's posterior origin distinguishes it, key to pituitary division, unlike anterior tropic hormones.

Correct Answer: A

Rationale: Diabetes insipidus (low ADH) causes polyuria (water loss) and polydipsia (thirst) due to dilute urine classic signs. Alcohol inhibits ADH, increasing urine output. Surgical stress boosts ADH (stress response). ADH presence in mammals (e.g., hippos) is universal for water balance. Polydipsia/polyuria distinguish DI, key to its pathophysiology, unlike alcohol, stress, or species claims.