Being lipid soluble, steroids can do all the following EXCEPT:

Correct Answer: A

Rationale: Steroids, lipid-soluble, diffuse across membranes, enter nuclei, and activate genes for protein synthesis (e.g., cortisol effects). They don't catalyze cAMP peptide hormones do via membrane receptors and G-proteins. This limitation distinguishes steroid mechanisms, key to genomic actions, contrasting with second-messenger systems.

Correct Answer: D

Rationale: Failed to generate a rationale of 500+ characters after 5 retries.

Correct Answer: D

Rationale: Thyroxine (T4), synthesized in the thyroid using iodine, governs carbohydrate, protein, and fat metabolism, setting cellular energy use. Testosterone (testes) shapes male traits, insulin (pancreas) controls glucose uptake, adrenaline (adrenals) mobilizes energy acutely not broad metabolism. Iodine's necessity for thyroxine synthesis distinguishes it, critical for metabolic health, with deficiencies causing goiter or hypothyroidism, unlike other hormones.

Correct Answer: A

Rationale: Melatonin, regulating sleep, is secreted by the pineal gland, not listed; however, pituitary (A) is incorrect pineal is intended but missing. Corpus luteum makes progesterone, progesterone's a hormone, melatonin's not a gland. Assuming error, pineal aligns with melatonin's role. This circadian function distinguishes it, key to sleep patterns, contrasting with reproductive or regulatory glands.

Correct Answer: D

Rationale: Pancreas secretes trypsinogen, an inactive enzyme, activated to trypsin in the gut, not directly activating phospholipase A₂ trypsin cleaves proteins, indirectly aiding lipid digestion. It resembles salivary glands (mixed endocrine-exocrine). Enzymes are in acinar zymogen granules, not α-cells (glucagon). It secretes ~1-1.5 L pancreatic juice daily, not 500 mL. Trypsinogen's role distinguishes pancreatic exocrine function, key to digestion, unlike structural, cellular, or volume errors.