Q.1 Which enzyme is primarily responsible for starch digestion in the mouth?
Pepsin
Amylase
Lipase
Trypsin
Explanation - Salivary amylase, secreted by the salivary glands, begins the breakdown of starch into maltose in the mouth.
Correct answer is: Amylase
Q.2 Which part of the digestive system is mainly responsible for water absorption?
Stomach
Small intestine
Large intestine
Esophagus
Explanation - The large intestine absorbs water and electrolytes from indigestible food residues, forming solid feces.
Correct answer is: Large intestine
Q.3 Which hormone stimulates pancreatic secretion of bicarbonate-rich fluid?
Secretin
Gastrin
Cholecystokinin
Somatostatin
Explanation - Secretin, released from the duodenum in response to acidic chyme, stimulates the pancreas to secrete a bicarbonate-rich fluid to neutralize the acid.
Correct answer is: Secretin
Q.4 Which cell type in the stomach secretes hydrochloric acid?
Chief cells
Parietal cells
Mucous cells
G cells
Explanation - Parietal cells, located in the stomach lining, secrete hydrochloric acid (HCl) which aids in protein digestion and activates pepsinogen.
Correct answer is: Parietal cells
Q.5 Which vitamin requires intrinsic factor for absorption?
Vitamin B12
Vitamin D
Vitamin K
Vitamin C
Explanation - Intrinsic factor, secreted by parietal cells of the stomach, is essential for absorption of vitamin B12 in the ileum.
Correct answer is: Vitamin B12
Q.6 Which of the following increases the surface area for nutrient absorption in the small intestine?
Rugae
Villi and microvilli
Haustra
Plicae semilunares
Explanation - Villi and microvilli in the small intestine increase the absorptive surface area, allowing efficient nutrient absorption.
Correct answer is: Villi and microvilli
Q.7 Which enzyme digests proteins in the stomach?
Pepsin
Amylase
Lipase
Maltase
Explanation - Pepsin, secreted as pepsinogen by chief cells, is activated in the acidic environment of the stomach and breaks proteins into peptides.
Correct answer is: Pepsin
Q.8 Which hormone stimulates gallbladder contraction and pancreatic enzyme secretion?
Secretin
Gastrin
Cholecystokinin
Motilin
Explanation - Cholecystokinin (CCK), released by the small intestine in response to fats and proteins, stimulates gallbladder contraction and pancreatic enzyme secretion.
Correct answer is: Cholecystokinin
Q.9 Which of the following is the main site of nutrient absorption?
Stomach
Small intestine
Large intestine
Esophagus
Explanation - The small intestine, with its villi and microvilli, is the primary site for absorption of nutrients including carbohydrates, proteins, and fats.
Correct answer is: Small intestine
Q.10 What is the main role of bile in digestion?
Protein digestion
Emulsification of fats
Carbohydrate digestion
Vitamin absorption
Explanation - Bile, produced by the liver and stored in the gallbladder, emulsifies fats into smaller droplets, increasing the surface area for pancreatic lipase activity.
Correct answer is: Emulsification of fats
Q.11 Which condition results from deficiency of digestive enzyme lactase?
Celiac disease
Lactose intolerance
Crohn's disease
Peptic ulcer
Explanation - Lactose intolerance occurs when the small intestine produces insufficient lactase, leading to difficulty digesting lactose in milk and dairy products.
Correct answer is: Lactose intolerance
Q.12 Which of the following secretions contains both digestive enzymes and bicarbonate?
Saliva
Pancreatic juice
Gastric juice
Bile
Explanation - Pancreatic juice contains digestive enzymes (amylase, lipase, proteases) and bicarbonate ions which neutralize stomach acid entering the duodenum.
Correct answer is: Pancreatic juice
Q.13 Which reflex increases gastric secretion in response to food in the stomach?
Gastrocolic reflex
Gastroileal reflex
Gastric phase reflex
Enterogastric reflex
Explanation - The gastric phase reflex is triggered by food in the stomach, stimulating gastric secretion via local and neural mechanisms.
Correct answer is: Gastric phase reflex
Q.14 Which enzyme converts trypsinogen to active trypsin in the small intestine?
Enterokinase
Pepsin
Amylase
Lipase
Explanation - Enterokinase (also called enteropeptidase) is secreted by the small intestine and converts trypsinogen to trypsin, initiating protein digestion.
Correct answer is: Enterokinase
Q.15 Which substance protects the stomach lining from autodigestion?
Pepsin
Mucus
HCl
Bile
Explanation - Mucus secreted by the stomach epithelium forms a protective barrier, preventing damage from acidic gastric juice and pepsin.
Correct answer is: Mucus
Q.16 Which vitamin is synthesized by bacteria in the large intestine?
Vitamin A
Vitamin K
Vitamin D
Vitamin C
Explanation - Gut bacteria in the large intestine synthesize vitamin K, which is important for blood clotting.
Correct answer is: Vitamin K
Q.17 Which process involves movement of chyme backward and forward in the small intestine to mix it with enzymes?
Peristalsis
Segmentation
Mass movement
Haustration
Explanation - Segmentation contractions in the small intestine mix chyme with digestive enzymes and bring it in contact with absorptive surfaces without moving it forward rapidly.
Correct answer is: Segmentation
Q.18 Which cell type in the stomach secretes pepsinogen?
Parietal cells
Chief cells
Mucous cells
G cells
Explanation - Chief cells in the stomach secrete pepsinogen, which is converted to pepsin in acidic conditions to digest proteins.
Correct answer is: Chief cells
Q.19 Which part of the small intestine receives bile and pancreatic juice?
Jejunum
Duodenum
Ileum
Cecum
Explanation - The duodenum, the first part of the small intestine, receives bile from the liver/gallbladder and pancreatic juice to aid in digestion.
Correct answer is: Duodenum
Q.20 Which of the following increases gastric acid secretion?
Secretin
Gastrin
Cholecystokinin
Somatostatin
Explanation - Gastrin, secreted by G cells in the stomach in response to food, stimulates parietal cells to secrete hydrochloric acid.
Correct answer is: Gastrin
Q.21 Which is the primary digestive enzyme in saliva?
Pepsin
Amylase
Lipase
Trypsin
Explanation - Salivary amylase breaks down starch into maltose in the oral cavity during mastication.
Correct answer is: Amylase
Q.22 Which hormone inhibits gastric emptying and slows intestinal motility?
Secretin
Gastrin
Cholecystokinin
Motilin
Explanation - Cholecystokinin slows gastric emptying and intestinal motility to allow time for fat digestion and absorption.
Correct answer is: Cholecystokinin
Q.23 Which is the first segment of the small intestine?
Jejunum
Duodenum
Ileum
Cecum
Explanation - The duodenum is the initial portion of the small intestine and plays a key role in digestion, receiving chyme, bile, and pancreatic juice.
Correct answer is: Duodenum
Q.24 Which enzyme digests lipids in the small intestine?
Amylase
Lipase
Pepsin
Trypsin
Explanation - Pancreatic lipase, aided by bile salts, breaks down triglycerides into fatty acids and glycerol for absorption.
Correct answer is: Lipase
Q.25 Which part of the digestive system contains Peyer's patches for immune surveillance?
Stomach
Duodenum
Ileum
Colon
Explanation - Peyer's patches in the ileum monitor intestinal bacteria and prevent the growth of pathogenic bacteria in the intestines.
Correct answer is: Ileum