Thyroxine (T_4) has great affinity for:

Correct Answer: A

Rationale: Thyroxine-binding globulin (TBG) has the highest affinity for T_4, binding most of it in plasma.

Correct Answer: C

Rationale: MMC occurs during fasting to clear the gut, distinct from BER; secretions decrease, and Phase I is quiescent, not contractile.

Correct Answer: C

Rationale: Gastrin stimulates histamine release from ECL cells, increasing acid secretion; histamine acts via cAMP, not Ca2+.

Correct Answer: D

Rationale: The adrenal medulla secretes epinephrine and norepinephrine.

Correct Answer: D

Rationale: All functions listed are affected or controlled by the pituitary gland.