1. Which layer of the gastrointestinal tract is responsible for the peristaltic movements? A. Mucosa B. Submucosa C. Muscularis D. Serosa Answer: C. Muscularis Rationale: The muscularis layer is responsible for the peristaltic movements that propel food through the digestive tract due to its smooth muscle composition. 2. What is the primary function of the stomach's pyloric sphincter? A. To regulate the release of food into the duodenum B. To mix food with gastric juices C. To absorb nutrients D. To secrete digestive enzymes Answer: A. To regulate the release of food into the duodenum Rationale: The pyloric sphincter controls the passage of partially digested food from the stomach to the duodenum, preventing backflow and regulating the rate of gastric emptying. 3. Which of the following is a feature of the small intestine that increases surface area for absorption? A. Rugae B. Haustra C. Villi D. Plicae circulares Answer: C. Villi Rationale: Villi are small, finger-like projections that increase the surface area of the small intestine, enhancing its ability to absorb nutrients effectively. 4. The enterohepatic circulation primarily involves the recycling of which substance? A. Glucose B. Amino acids C. Bile salts D. Gastric acid