Free Human Digestive System MCQs with Answers

51. The function of bile salts is to

• A. Digest fats enzymatically
• B. Emulsify fats
• C. Absorb fatty acids
• D. Produce lipase

Explanation: Bile salts emulsify fats, breaking large fat droplets into smaller ones to increase surface area for lipase action.

52. Most absorption occurs in the

• A. Stomach
• B. Duodenum
• C. Ileum
• D. Colon

Explanation: Most nutrient absorption occurs in the ileum (small intestine), which has villi and microvilli for maximum surface area.

53. Trypsin is activated by

• A. HCl
• B. Enterokinase/Enteropeptidase
• C. Pepsin
• D. Bile

Explanation: Enterokinase (enteropeptidase) from intestinal brush border activates trypsinogen to trypsin, which then activates other pancreatic enzymes.

54. Lactase deficiency causes

• A. Diabetes
• B. Lactose intolerance
• C. Celiac disease
• D. Pernicious anemia

Explanation: Lactase deficiency leads to lactose intolerance, causing bloating, gas, and diarrhea when dairy is consumed.

55. Intrinsic factor is required for absorption of

• A. Iron
• B. Vitamin B12
• C. Calcium
• D. Vitamin D

Explanation: Intrinsic factor from gastric parietal cells binds vitamin B12 for absorption in the ileum; its deficiency causes pernicious anemia.

56. The hepatic portal vein carries blood from the

• A. Liver to heart
• B. Intestines to liver
• C. Liver to kidneys
• D. Spleen to liver

Explanation: The hepatic portal vein carries nutrient-rich blood from the digestive organs to the liver for processing.

57. Pancreatic juice is alkaline due to

• A. HCl
• B. Bicarbonate
• C. Pepsin
• D. Bile

Explanation: Sodium bicarbonate in pancreatic juice neutralizes acidic chyme from the stomach, creating optimal pH for enzymes.

58. Chylomicrons are formed in

• A. Liver
• B. Intestinal epithelial cells
• C. Blood
• D. Adipose tissue

Explanation: Chylomicrons (lipoprotein particles containing triglycerides) are formed in intestinal epithelial cells after fat absorption.

59. Which is an enzyme activator secreted by the intestinal glands:

• A. Amylase
• B. Pepsinogens
• C. Enterokinase
• D. Lipase

Explanation: Enterokinase from the duodenal lining converts trypsinogen into active trypsin, which then activates the other pancreatic proenzymes in turn. Pepsinogen is itself an inactive precursor rather than an activator, and it is activated by hydrochloric acid in the stomach, which makes it the tempting answer. Amylase and lipase are ordinary digestive enzymes.