Which motor activity is primarily responsible for mixing and churning food in the small intestine to enhance digestion and absorption?

Correct Answer: B

Rationale: Segmentation mixes chyme with digestive enzymes and increases mucosal contact for absorption in the small intestine.

Correct Answer: D

Rationale: Trypsin, an endopeptidase, cleaves peptide bonds within protein chains, producing smaller polypeptides.

Correct Answer: A

Rationale: cAMP is a common secondary messenger in hormone signaling pathways.

Correct Answer: D

Rationale: Mitochondria provide ATP for active transport of nutrients like glucose in the proximal convoluted tubule.

Correct Answer: A

Rationale: Juxtaglomerular cells secrete renin to regulate blood pressure and filtration.