Steroid hormones function by binding to receptor proteins within the Once the hormone binds to a receptor, it activates

Correct Answer: B

Rationale: Steroid hormones (e.g., cortisol) bind nuclear receptors, entering the nucleus to activate gene transcription altering protein synthesis over hours. Nuclear second messengers aren't typical cAMP is membrane-based. Membrane binding fits peptides (e.g., insulin), not steroids, and genes aren't at membranes. Nuclear gene activation distinguishes steroid action, key to their genomic effects, unlike messenger or membrane errors.

Correct Answer: D

Rationale: Ovary is controlled by anterior pituitary's FSH/LH, driving follicle growth and ovulation reproductive link. Pancreas (insulin) isn't pituitary-regulated autonomous. Parathyroid (PTH) self-regulates via calcium. Adrenal medulla (epinephrine) is neural, not pituitary. Ovary's pituitary dependence distinguishes it, critical for gonadal function, unlike independent or neural glands.

Correct Answer: C

Rationale: Adult hypothyroidism (low T3/T4) causes myxedema fatigue, weight gain, cold intolerance from slow metabolism. Graves is hyperthyroidism opposite. Diabetes insipidus is ADH lack water loss. Acromegaly is GH excess bone growth. Myxedema's hypometabolic state distinguishes it, key to thyroid deficiency, unlike hyperactive, water, or growth conditions.

Correct Answer: D

Rationale: Calcium aids clotting (coagulation cascade), hardens bone (hydroxyapatite), and enables nerve conduction/muscle contraction (depolarization, release) multifaceted. Each is true: clotting stops bleeding, bone supports, nerve/muscle drive movement. All-inclusive role distinguishes calcium, key to physiology, unlike partial functions.

Correct Answer: C

Rationale: Glucagon (pancreas) opposes insulin by raising blood glucose via glycogenolysis/gluconeogenesis direct antagonist. Cortisol (adrenal) raises glucose longer-term, indirect. Norepinephrine/epinephrine (medulla) spike glucose acutely, stress-related. Mineralocorticoids (aldosterone) manage sodium, not glucose. Glucagon's glucose-elevating role distinguishes it, critical for balance, unlike stress or electrolyte hormones.