does not increase growth hormone secretion.

Correct Answer: C

Rationale: Low amino acids do not stimulate GH; low glucose and stress do.

Correct Answer: A

Rationale: Most Ca2+ (~65%) is reabsorbed in the PCT passively, with further regulated reabsorption in the DCT.

Correct Answer: C

Rationale: The anterior pituitary produces 5 trophic hormones: TSH, ACTH, FSH, LH, and GH (PRL is sometimes included but not always trophic).

Correct Answer: B

Rationale: Vitamin C is water-soluble, unlike the fat-soluble vitamins A, D, E, and K.

Correct Answer: D

Rationale: The submandibular gland produces ~70% of saliva; parotid is serous, not mucous, and sublingual is mixed.