Growth hormone, via , stimulates growth in a long bone to influence its length.

Correct Answer: C

Rationale: IGF-1 from GH stimulates epiphyseal plate growth.

Correct Answer: B

Rationale: Calcitonin increases renal Ca2+ excretion and decreases blood Ca2+ by promoting bone deposition, not resorption. It's stimulated by high Ca2+ and gastrin, not decreased gastrin or CCK2.

Correct Answer: B

Rationale: B (beta) cells are the most abundant in the endocrine pancreas, producing insulin.

Correct Answer: C

Rationale: LDL primarily contains apolipoprotein B-100, distinguishing it from chylomicrons (B-48).

Correct Answer: A

Rationale: Cl^- activates salivary α-amylase; its optimum pH is ~6.9, it produces maltose (not glucose), and targets α-1-4 linkages, not lipids.