In humans, structures that release digestive secretions directly into the small intestine include both the

Correct Answer: D

Rationale: The pancreas releases digestive enzymes and the gall bladder releases bile directly into the small intestine via ducts to aid digestion. Salivary glands (A, C) secrete into the mouth, not the small intestine. Lacteals absorb fats, not secrete. Villi are absorptive structures, not secretory.

Correct Answer: C

Rationale: Partly-digested food (chyme) moves from the stomach to the small intestine for further digestion and absorption, making C correct. The gullet is before the stomach, the appendix is a side structure, and the large intestine follows the small intestine.

Correct Answer: A

Rationale: The appendix is attached to the cecum, part of the colon, making A correct.

Correct Answer: D

Rationale: Low stomach pH converts pepsinogen to active pepsin for protein digestion, making D correct.

Correct Answer: A

Rationale: The gallbladder stores bile for fat digestion, making A correct.