1. What is the human dental formula for a normal adult?
Correct Answer: B (2123/2123)
The adult human dental formula is 2123/2123, representing 2 incisors, 1 canine, 2 premolars, and 3 molars in each half of the upper and lower jaw.
The adult human dental formula is 2123/2123, representing 2 incisors, 1 canine, 2 premolars, and 3 molars in each half of the upper and lower jaw.
2. Which cell type in the gastric mucosa secretes hydrochloric acid (HCl) and intrinsic factor?
Correct Answer: C (Oxyntic (Parietal) cells)
Parietal (oxyntic) cells secrete HCl (which maintains stomach pH between 1.5–2.0) and Castle’s intrinsic factor (essential for absorption of vitamin B12).
Parietal (oxyntic) cells secrete HCl (which maintains stomach pH between 1.5–2.0) and Castle’s intrinsic factor (essential for absorption of vitamin B12).
3. Which enzyme activates trypsinogen into active trypsin in the small intestine?
Correct Answer: A (Enterokinase)
Enterokinase (enteropeptidase), secreted by the intestinal mucosa, cleaves the inactive proenzyme trypsinogen into active trypsin.
Enterokinase (enteropeptidase), secreted by the intestinal mucosa, cleaves the inactive proenzyme trypsinogen into active trypsin.
4. The hardest substance in the human body that covers the anatomical crown of a tooth is:
Correct Answer: B (Enamel)
Enamel is ectodermal in origin, secreted by ameloblasts, and consists of over 96% mineralized hydroxyapatite, making it the hardest biological structure.
Enamel is ectodermal in origin, secreted by ameloblasts, and consists of over 96% mineralized hydroxyapatite, making it the hardest biological structure.
5. The opening of the hepatopancreatic ampulla (ampulla of Vater) into the duodenum is guarded by the:
Correct Answer: B (Sphincter of Oddi)
The Sphincter of Oddi regulates the flow of bile and pancreatic secretions into the descending duodenum and prevents backflow of duodenal contents.
The Sphincter of Oddi regulates the flow of bile and pancreatic secretions into the descending duodenum and prevents backflow of duodenal contents.
6. Brunner’s glands are characteristic histological structures located in the submucosa of the:
Correct Answer: B (Duodenum)
Brunner’s glands are branched tubuloalveolar glands situated in the duodenal submucosa that secrete alkaline, bicarbonate-rich mucus to protect from acidic chyme.
Brunner’s glands are branched tubuloalveolar glands situated in the duodenal submucosa that secrete alkaline, bicarbonate-rich mucus to protect from acidic chyme.
7. Which of the following is an inactive proenzyme secreted by gastric chief cells?
Correct Answer: A (Pepsinogen)
Chief (peptic) cells secrete pepsinogen, which is converted to active pepsin by hydrochloric acid in the stomach lumen.
Chief (peptic) cells secrete pepsinogen, which is converted to active pepsin by hydrochloric acid in the stomach lumen.
8. The structural and functional units of the human liver are known as:
Correct Answer: B (Hepatic lobules)
Hepatic lobules are hexagonal cylinders composed of hepatic cells arranged in radiating cords, covered by Glisson’s capsule.
Hepatic lobules are hexagonal cylinders composed of hepatic cells arranged in radiating cords, covered by Glisson’s capsule.
9. What thin connective tissue sheath surrounds each hepatic lobule in mammals?
Correct Answer: C (Glisson’s capsule)
Glisson’s capsule is a layer of connective tissue that wraps the liver external surface and forms sheaths around hepatic lobules.
Glisson’s capsule is a layer of connective tissue that wraps the liver external surface and forms sheaths around hepatic lobules.
10. Specialized macrophages residing in the liver sinusoids that phagocytize old RBCs and bacteria are:
Correct Answer: C (Kupffer cells)
Kupffer cells are specialized stellate macrophages located in the sinusoidal lining of the liver, clearing microbial debris and worn-out blood elements.
Kupffer cells are specialized stellate macrophages located in the sinusoidal lining of the liver, clearing microbial debris and worn-out blood elements.
11. Salivary amylase (ptyalin) converts starch primarily into which disaccharide?
Correct Answer: B (Maltose)
Salivary amylase hydrolyzes alpha-1,4 glycosidic bonds in starch to produce maltose, maltotriose, and alpha-limit dextrins at an optimum pH of 6.8.
Salivary amylase hydrolyzes alpha-1,4 glycosidic bonds in starch to produce maltose, maltotriose, and alpha-limit dextrins at an optimum pH of 6.8.
12. Which hormone stimulates the gallbladder to contract and release concentrated bile?
Correct Answer: B (Cholecystokinin (CCK))
CCK is synthesized by I-cells in the duodenum and jejunum in response to fatty acids and amino acids, stimulating gallbladder contraction and pancreatic enzyme release.
CCK is synthesized by I-cells in the duodenum and jejunum in response to fatty acids and amino acids, stimulating gallbladder contraction and pancreatic enzyme release.
13. The duct arising from the gallbladder is the:
Correct Answer: B (Cystic duct)
The cystic duct drains the gallbladder and joins the common hepatic duct to form the common bile duct (ductus choledochus).
The cystic duct drains the gallbladder and joins the common hepatic duct to form the common bile duct (ductus choledochus).
14. What constitutes the major portion of human succus entericus (intestinal juice)?
Correct Answer: B (Secretions of crypts of Lieberkühn and Brunner’s glands)
Succus entericus is the complete digestive secretion produced collectively by the crypts of Lieberkühn and duodenal Brunner’s glands.
Succus entericus is the complete digestive secretion produced collectively by the crypts of Lieberkühn and duodenal Brunner’s glands.
15. Paneth cells located at the base of the crypts of Lieberkühn secrete:
Correct Answer: C (Lysozyme and defensins)
Paneth cells provide mucosal immunity by secreting antimicrobial compounds including lysozymes and alpha-defensins into the intestinal lumen.
Paneth cells provide mucosal immunity by secreting antimicrobial compounds including lysozymes and alpha-defensins into the intestinal lumen.
16. The primary site of lipid emulsification in the human digestive system is:
Correct Answer: C (Small intestine (Duodenum))
Emulsification occurs primarily in the duodenum where bile salts breakdown large lipid droplets into smaller micelles, increasing surface area for lipase action.
Emulsification occurs primarily in the duodenum where bile salts breakdown large lipid droplets into smaller micelles, increasing surface area for lipase action.
17. Which proteolytic enzyme is responsible for the coagulation of milk protein (casein) in infants?
Correct Answer: A (Rennin (Chymosin))
Rennin (with double ‘n’) is a proteolytic enzyme found in infant gastric juice that curdles milk by converting soluble casein into insoluble paracaseinate.
Rennin (with double ‘n’) is a proteolytic enzyme found in infant gastric juice that curdles milk by converting soluble casein into insoluble paracaseinate.
18. Chylomicrons are transported from enterocytes into the systemic circulation primarily through:
Correct Answer: B (Lacteals (lymphatic capillaries))
Reformed triglycerides and cholesterol are packaged into chylomicrons and exocytosed into central lacteals of intestinal villi due to their large size.
Reformed triglycerides and cholesterol are packaged into chylomicrons and exocytosed into central lacteals of intestinal villi due to their large size.
19. The anatomical condition in which teeth are embedded in sockets of the jaw bones is termed:
Correct Answer: B (Thecodont)
Thecodont dentition refers to teeth anchored firmly in deep bony sockets (alveoli) of the maxilla and mandible.
Thecodont dentition refers to teeth anchored firmly in deep bony sockets (alveoli) of the maxilla and mandible.
20. What is the correct sequence of the four basic histological layers of the alimentary canal from outer to inner?
Correct Answer: B (Serosa → Muscularis → Submucosa → Mucosa)
From external to internal: Serosa (outermost visceral peritoneum) → Muscularis (outer longitudinal, inner circular) → Submucosa → Mucosa (innermost layer).
From external to internal: Serosa (outermost visceral peritoneum) → Muscularis (outer longitudinal, inner circular) → Submucosa → Mucosa (innermost layer).
21. Auerbach’s (myenteric) nerve plexus is located between which layers of the gut wall?
Correct Answer: B (Longitudinal muscle and circular muscle layers)
The myenteric (Auerbach’s) plexus lies between the outer longitudinal and inner circular muscle layers, governing gastrointestinal motility and peristalsis.
The myenteric (Auerbach’s) plexus lies between the outer longitudinal and inner circular muscle layers, governing gastrointestinal motility and peristalsis.
22. Meissner’s plexus is primarily responsible for regulating:
Correct Answer: B (Gastrointestinal secretions and local blood flow)
Meissner’s (submucosal) plexus controls glandular secretions, absorptive functions, and local vascular tone in the submucosal layer.
Meissner’s (submucosal) plexus controls glandular secretions, absorptive functions, and local vascular tone in the submucosal layer.
23. Which biological fluid contains no digestive enzymes yet plays a crucial role in digestion?
Correct Answer: C (Bile)
Bile contains bile salts, phospholipids, cholesterol, and bile pigments, but lacks enzymatic proteins. It digests fats solely via mechanical emulsification.
Bile contains bile salts, phospholipids, cholesterol, and bile pigments, but lacks enzymatic proteins. It digests fats solely via mechanical emulsification.
24. Peyer’s patches are characteristic aggregations of lymphoid follicles found in the:
Correct Answer: C (Ileum)
Peyer’s patches are specialized clusters of mucosal-associated lymphoid tissue (MALT) located prominently in the lamina propria and submucosa of the ileum.
Peyer’s patches are specialized clusters of mucosal-associated lymphoid tissue (MALT) located prominently in the lamina propria and submucosa of the ileum.
25. The duct of Wirsung is the primary excretory duct of the:
Correct Answer: C (Pancreas)
The duct of Wirsung is the main pancreatic duct that joins the common bile duct to form the ampulla of Vater.
The duct of Wirsung is the main pancreatic duct that joins the common bile duct to form the ampulla of Vater.
26. The gastroesophageal sphincter prevents reflux of stomach contents into the:
Correct Answer: B (Esophagus)
The gastroesophageal (cardiac) sphincter regulates the bolus entry into the stomach and prevents acidic gastric juice regurgitation into the esophagus.
The gastroesophageal (cardiac) sphincter regulates the bolus entry into the stomach and prevents acidic gastric juice regurgitation into the esophagus.
27. Which form of bilirubin is excreted into the bile after hepatocyte metabolism?
Correct Answer: B (Conjugated bilirubin (Bilirubin diglucuronide))
Hepatocytes conjugate lipid-soluble unconjugated bilirubin with glucuronic acid to make it water-soluble before secretion into bile.
Hepatocytes conjugate lipid-soluble unconjugated bilirubin with glucuronic acid to make it water-soluble before secretion into bile.
28. Which hormone triggers the pancreatic acinar cells to secrete large amounts of bicarbonate-rich fluid?
Correct Answer: A (Secretin)
Secretin is released by duodenal S-cells in response to low pH, stimulating pancreatic ductal cells to secrete watery bicarbonate fluid to neutralize gastric acid.
Secretin is released by duodenal S-cells in response to low pH, stimulating pancreatic ductal cells to secrete watery bicarbonate fluid to neutralize gastric acid.
29. The longitudinal muscle layer of the large intestine forms three distinct ribbon-like bands called:
Correct Answer: B (Taeniae coli)
Taeniae coli are three thickened longitudinal bands of smooth muscle on the outer colon wall that contract to create pouches called haustra.
Taeniae coli are three thickened longitudinal bands of smooth muscle on the outer colon wall that contract to create pouches called haustra.
30. Severe protein deficiency in children aged 1–5 years presenting with edema and potbelly is called:
Correct Answer: B (Kwashiorkor)
Kwashiorkor is caused by adequate caloric intake with deficient dietary protein, resulting in hypoalbuminemia, ascites, edema, and enlarged fatty liver.
Kwashiorkor is caused by adequate caloric intake with deficient dietary protein, resulting in hypoalbuminemia, ascites, edema, and enlarged fatty liver.
31. Marasmus is differentiated clinically from Kwashiorkor primarily by:
Correct Answer: A (Absence of edema and severe wasting of both muscle and fat)
Marasmus results from concurrent deficiency of both total calories and proteins, causing marked wasting of muscle/adipose tissue without edema.
Marasmus results from concurrent deficiency of both total calories and proteins, causing marked wasting of muscle/adipose tissue without edema.
32. The gross calorific value of proteins is approximately:
Correct Answer: B (5.65 kcal/g)
The gross calorific value (bomb calorimeter value) of protein is 5.65 kcal/g, whereas its physiological fuel value is approximately 4.0 kcal/g.
The gross calorific value (bomb calorimeter value) of protein is 5.65 kcal/g, whereas its physiological fuel value is approximately 4.0 kcal/g.
33. Which nutrient yields the highest gross energy per gram during complete combustion?
Correct Answer: C (Fats (9.45 kcal/g))
Fats possess the highest gross calorific value (9.45 kcal/g) and physiological fuel value (9.0 kcal/g) due to their reduced carbon state.
Fats possess the highest gross calorific value (9.45 kcal/g) and physiological fuel value (9.0 kcal/g) due to their reduced carbon state.
34. Digestion of carbohydrates begins in the:
Correct Answer: A (Oral cavity)
Carbohydrate digestion initiates in the oral cavity where salivary amylase cleaves approximately 30% of ingested dietary starch into disaccharides.
Carbohydrate digestion initiates in the oral cavity where salivary amylase cleaves approximately 30% of ingested dietary starch into disaccharides.
35. Which salivary gland is the largest and located inferior and anterior to the ears?
Correct Answer: C (Parotid gland)
The parotid glands are the largest paired salivary glands, draining serous secretions via Stensen’s duct into the oral vestibule opposite the upper second molar.
The parotid glands are the largest paired salivary glands, draining serous secretions via Stensen’s duct into the oral vestibule opposite the upper second molar.
36. Stensen’s duct drains saliva from which pair of glands?
Correct Answer: A (Parotid glands)
Stensen’s duct is the excretory conduit of the parotid gland. Wharton’s duct corresponds to the submandibular gland, and Rivinus’ ducts to the sublingual.
Stensen’s duct is the excretory conduit of the parotid gland. Wharton’s duct corresponds to the submandibular gland, and Rivinus’ ducts to the sublingual.
37. Wharton’s duct drains secretions from which salivary gland?
Correct Answer: B (Submandibular (submaxillary))
Wharton’s duct drains mixed seromucous saliva from the submandibular gland onto the sublingual caruncle beneath the tongue.
Wharton’s duct drains mixed seromucous saliva from the submandibular gland onto the sublingual caruncle beneath the tongue.
38. The cartilaginous flap that prevents bolus entry into the glottis during deglutition is the:
Correct Answer: C (Epiglottis)
The epiglottis folds downward over the laryngeal inlet (glottis) during swallowing to prevent aspiration into the respiratory tract.
The epiglottis folds downward over the laryngeal inlet (glottis) during swallowing to prevent aspiration into the respiratory tract.
39. The stomach mucosa contains longitudinal folds known as:
Correct Answer: B (Rugae)
Gastric rugae are mucosal and submucosal folds that allow significant luminal expansion and distension as the stomach fills with food.
Gastric rugae are mucosal and submucosal folds that allow significant luminal expansion and distension as the stomach fills with food.
40. The intestinal mucosal folds that permanently project into the lumen to enhance absorptive surface area are:
Correct Answer: B (Plicae circulares (Valves of Kerckring))
Plicae circulares are large, permanent circular folds of the mucosa and submucosa present throughout the small intestine (most prominent in the jejunum).
Plicae circulares are large, permanent circular folds of the mucosa and submucosa present throughout the small intestine (most prominent in the jejunum).
41. The primary enzyme responsible for hydrolyzing triglycerides into fatty acids and monoglycerides is:
Correct Answer: B (Pancreatic lipase (Steapsin))
Pancreatic lipase is the primary lipolytic enzyme in the human body, cleaving dietary triglycerides into diacylglycerols, monoacylglycerols, and free fatty acids.
Pancreatic lipase is the primary lipolytic enzyme in the human body, cleaving dietary triglycerides into diacylglycerols, monoacylglycerols, and free fatty acids.
42. Castle’s intrinsic factor secreted by parietal cells is indispensable for the absorption of:
Correct Answer: C (Vitamin B12 (Cobalamin))
Intrinsic factor forms a complex with vitamin B12 in the upper digestive tract, allowing receptor-mediated endocytosis in the terminal ileum.
Intrinsic factor forms a complex with vitamin B12 in the upper digestive tract, allowing receptor-mediated endocytosis in the terminal ileum.
43. Defective absorption of Vitamin B12 due to loss of gastric parietal cells causes:
Correct Answer: B (Pernicious anemia)
Autoimmune destruction or atrophy of gastric parietal cells abolishes intrinsic factor secretion, leading to megaloblastic pernicious anemia.
Autoimmune destruction or atrophy of gastric parietal cells abolishes intrinsic factor secretion, leading to megaloblastic pernicious anemia.
44. The vermiform appendix originates as a blind tubular pouch from the:
Correct Answer: A (Cecum)
The vermiform appendix is a narrow, finger-like vestigial lymphoid diverticulum that arises posteromedially from the blind pouch of the cecum.
The vermiform appendix is a narrow, finger-like vestigial lymphoid diverticulum that arises posteromedially from the blind pouch of the cecum.
45. Which intestinal brush border enzyme converts lactose into glucose and galactose?
Correct Answer: C (Lactase)
Lactase (beta-galactosidase) hydrolyzes the disaccharide lactose into its constituent monosaccharide monomers: D-glucose and D-galactose.
Lactase (beta-galactosidase) hydrolyzes the disaccharide lactose into its constituent monosaccharide monomers: D-glucose and D-galactose.
46. Enteroendocrine G-cells of the stomach antrum secrete which hormone?
Correct Answer: A (Gastrin)
Gastrin is secreted by G-cells located in pyloric antral glands, stimulating parietal cells to synthesize HCl and promoting gastric mucosal growth.
Gastrin is secreted by G-cells located in pyloric antral glands, stimulating parietal cells to synthesize HCl and promoting gastric mucosal growth.
47. Which gastrointestinal peptide inhibits gastric secretion and motility?
Correct Answer: B (Gastric Inhibitory Peptide (GIP / Enterogastrone))
GIP (glucose-dependent insulinotropic peptide / enterogastrone) slows gastric emptying and inhibits acid production while stimulating insulin release.
GIP (glucose-dependent insulinotropic peptide / enterogastrone) slows gastric emptying and inhibits acid production while stimulating insulin release.
48. Bile salts (Sodium taurocholate and glycocholate) lower surface tension to facilitate fat:
Correct Answer: B (Emulsification)
Amphipathic bile salts break large lipid globules into submicroscopic droplets (micelles), providing maximum surface area for pancreatic lipase activity.
Amphipathic bile salts break large lipid globules into submicroscopic droplets (micelles), providing maximum surface area for pancreatic lipase activity.
49. Which of the following is NOT an endopeptidase?
Correct Answer: D (Carboxypeptidase)
Carboxypeptidase is an exopeptidase that hydrolyzes peptide bonds at the C-terminus of proteins, unlike endopeptidases that cleave internal peptide bonds.
Carboxypeptidase is an exopeptidase that hydrolyzes peptide bonds at the C-terminus of proteins, unlike endopeptidases that cleave internal peptide bonds.
50. Which cofactor is required for the catalytic activation and stability of salivary amylase?
Correct Answer: A (Chloride ions (Cl⁻))
Chloride ions (Cl⁻) act as allosteric activators of salivary amylase (ptyalin), enhancing its starch-hydrolyzing activity.
Chloride ions (Cl⁻) act as allosteric activators of salivary amylase (ptyalin), enhancing its starch-hydrolyzing activity.
51. The pH of normal human resting saliva typically ranges around:
Correct Answer: B (6.4 – 6.8)
Human saliva is slightly acidic to nearly neutral, with an average optimum pH of 6.8 for salivary amylase function.
Human saliva is slightly acidic to nearly neutral, with an average optimum pH of 6.8 for salivary amylase function.
52. Which organ synthesizes and secretes angiotensinogen and plasma proteins like albumin?
Correct Answer: C (Liver)
The liver is the principal synthetic factory for plasma albumin, clotting factors (fibrinogen, prothrombin), and angiotensinogen.
The liver is the principal synthetic factory for plasma albumin, clotting factors (fibrinogen, prothrombin), and angiotensinogen.
53. In humans, the diphyodont condition means that:
Correct Answer: B (Two sets of teeth develop during a lifetime)
Diphyodonty is the dental condition characterized by two successive sets: primary deciduous (milk) teeth and permanent adult teeth.
Diphyodonty is the dental condition characterized by two successive sets: primary deciduous (milk) teeth and permanent adult teeth.
54. Which primary teeth are entirely absent in human deciduous dentition?
Correct Answer: C (Premolars)
The deciduous dental formula is 2102/2102. Premolars are completely absent in the primary dentition and erupt only as permanent teeth.
The deciduous dental formula is 2102/2102. Premolars are completely absent in the primary dentition and erupt only as permanent teeth.
55. Which layer of the tooth structure is produced by odontoblast cells?
Correct Answer: B (Dentine)
Dentine is mesodermal in origin, synthesized and maintained by odontoblasts that line the outer boundary of the dental pulp cavity.
Dentine is mesodermal in origin, synthesized and maintained by odontoblasts that line the outer boundary of the dental pulp cavity.
56. Bile pigments (bilirubin and biliverdin) are breakdown products of:
Correct Answer: C (Hemoglobin)
Bile pigments originate from the catabolism of the iron-porphyrin heme ring during the degradation of senescent erythrocytes in the reticuloendothelial system.
Bile pigments originate from the catabolism of the iron-porphyrin heme ring during the degradation of senescent erythrocytes in the reticuloendothelial system.
57. Absorption of glucose and amino acids across the apical membrane of intestinal enterocytes primarily occurs via:
Correct Answer: B (Secondary active transport (Na⁺ cotransport / SGLT-1))
Glucose, galactose, and most L-amino acids are co-transported with Na⁺ down the electrochemical sodium gradient established by Na⁺/K⁺ ATPase.
Glucose, galactose, and most L-amino acids are co-transported with Na⁺ down the electrochemical sodium gradient established by Na⁺/K⁺ ATPase.
58. Dietary fructose is absorbed into intestinal epithelial cells primarily via:
Correct Answer: A (Facilitated diffusion (via GLUT5))
Fructose entry across the enterocyte apical membrane is facilitated through GLUT5 transporter carriers without ATP expenditure.
Fructose entry across the enterocyte apical membrane is facilitated through GLUT5 transporter carriers without ATP expenditure.
59. The yellowish discoloration of skin and sclera during jaundice indicates accumulation of:
Correct Answer: B (Birubin)
Jaundice (icterus) occurs when circulating serum bilirubin concentrations exceed approximately 2–2.5 mg/dL, depositing pigment into elastic tissue.
Jaundice (icterus) occurs when circulating serum bilirubin concentrations exceed approximately 2–2.5 mg/dL, depositing pigment into elastic tissue.
60. Which organ in the human alimentary canal produces NO digestive enzymes whatsoever?
Correct Answer: B (Esophagus)
The esophagus acts solely as a muscular conduit to convey food via peristalsis and secretes lubricating mucus without enzymatic machinery.
The esophagus acts solely as a muscular conduit to convey food via peristalsis and secretes lubricating mucus without enzymatic machinery.
61. Vomiting is an involuntary reflex coordinated by the vomiting center located in the:
Correct Answer: C (Medulla oblongata)
The bilateral emetic (vomiting) reflex centers and the chemoreceptor trigger zone (CTZ) reside in the brainstem medulla oblongata.
The bilateral emetic (vomiting) reflex centers and the chemoreceptor trigger zone (CTZ) reside in the brainstem medulla oblongata.
62. Which proteolytic enzyme cleaves peptide bonds at basic amino acids (Lysine and Arginine)?
Correct Answer: A (Trypsin)
Trypsin is a serine endopeptidase that hydrolyzes peptide bonds specifically at the carboxyl side of basic amino acid residues (Lys, Arg).
Trypsin is a serine endopeptidase that hydrolyzes peptide bonds specifically at the carboxyl side of basic amino acid residues (Lys, Arg).
63. Chymotrypsin preferentially cleaves peptide bonds adjacent to:
Correct Answer: A (Aromatic amino acids (Phenylalanine, Tyrosine, Tryptophan))
Chymotrypsin possesses a deep hydrophobic binding pocket tailored to accommodate bulky aromatic side chains.
Chymotrypsin possesses a deep hydrophobic binding pocket tailored to accommodate bulky aromatic side chains.
64. Which sphincter regulates the discharge of chyme from the stomach into the duodenum?
Correct Answer: B (Pyloric sphincter)
The pyloric sphincter is a thickened smooth muscle ring that controls the intermittent passage of gastric chyme into the duodenal bulb.
The pyloric sphincter is a thickened smooth muscle ring that controls the intermittent passage of gastric chyme into the duodenal bulb.
65. What is the physiological fuel value of carbohydrates in the human body?
Correct Answer: A (4.0 kcal/g)
The actual biological/physiological energy yield of dietary carbohydrate available to human tissues is 4.0 kcal/g (17 kJ/g).
The actual biological/physiological energy yield of dietary carbohydrate available to human tissues is 4.0 kcal/g (17 kJ/g).
66. Nucleases present in the pancreatic juice include:
Correct Answer: A (Deoxyribonuclease and Ribonuclease)
Pancreatic juice contains endonucleases (DNase and RNase) that degrade nucleic acids into nucleotides; subsequent nucleotidases are brush border enzymes.
Pancreatic juice contains endonucleases (DNase and RNase) that degrade nucleic acids into nucleotides; subsequent nucleotidases are brush border enzymes.
67. The physiological process of rhythmic contraction and relaxation propelling food along the gut is:
Correct Answer: B (Peristalsis)
Peristalsis is the progressive wave of coordinated smooth muscle contraction preceded by relaxation that propels luminal contents unidirectionally.
Peristalsis is the progressive wave of coordinated smooth muscle contraction preceded by relaxation that propels luminal contents unidirectionally.
68. Gallstones (cholelithiasis) are predominantly composed of precipitated:
Correct Answer: A (Cholesterol)
Over 75–80% of gallstones form when the cholesterol concentration in bile exceeds the solubilizing capacity of bile salts and lecithin.
Over 75–80% of gallstones form when the cholesterol concentration in bile exceeds the solubilizing capacity of bile salts and lecithin.
69. The functional role of mucus secreted by goblet cells along the entire tract is to:
Correct Answer: B (Lubricate luminal walls and protect the epithelium from mechanical/chemical abrasion)
Mucin glycoproteins form a viscoelastic protective barrier against mechanical sheer, pathogenic invasion, and autodigestion by digestive enzymes.
Mucin glycoproteins form a viscoelastic protective barrier against mechanical sheer, pathogenic invasion, and autodigestion by digestive enzymes.
70. The hepatic portal vein carries nutrient-rich blood from the gastrointestinal tract directly to the:
Correct Answer: C (Liver)
The hepatic portal system directs venous blood draining stomach, intestines, and spleen into liver sinusoids for first-pass metabolic processing.
The hepatic portal system directs venous blood draining stomach, intestines, and spleen into liver sinusoids for first-pass metabolic processing.
71. Which cells secrete mucus in the gastric pits of the stomach?
Correct Answer: A (Mucous neck cells)
Mucous neck cells, along with surface epithelial foveolar cells, secrete insoluble alkaline mucus that safeguards the gastric lining against corrosive gastric juices.
Mucous neck cells, along with surface epithelial foveolar cells, secrete insoluble alkaline mucus that safeguards the gastric lining against corrosive gastric juices.
72. Which vitamin is synthesized by symbiotic colonic microflora (e.g., E. coli)?
Correct Answer: B (Vitamin K)
Normal intestinal gut microbiota synthesize substantial amounts of Vitamin K (menaquinone) and certain B vitamins (biotin, B12), which are absorbed in the colon.
Normal intestinal gut microbiota synthesize substantial amounts of Vitamin K (menaquinone) and certain B vitamins (biotin, B12), which are absorbed in the colon.
73. The primary form of mechanical digestion occurring in the small intestine is:
Correct Answer: C (Segmentation)
Segmentation involves alternating rhythmic circular muscle contractions that chop and mix chyme thoroughly with bile and pancreatic enzymes.
Segmentation involves alternating rhythmic circular muscle contractions that chop and mix chyme thoroughly with bile and pancreatic enzymes.
74. The accessory pancreatic duct that empties independently into the duodenum is called the:
Correct Answer: B (Duct of Santorini)
The duct of Santorini is the embryonic accessory duct of the dorsal pancreatic bud, draining directly into the minor duodenal papilla.
The duct of Santorini is the embryonic accessory duct of the dorsal pancreatic bud, draining directly into the minor duodenal papilla.
75. The innermost mucous membrane layer lining the lumen of the gut is called:
Correct Answer: A (Mucosa)
The mucosa consists of surface epithelium, underlying lamina propria (connective tissue), and a thin muscularis mucosae layer.
The mucosa consists of surface epithelium, underlying lamina propria (connective tissue), and a thin muscularis mucosae layer.
76. The muscular junction between the ileum and the cecum that prevents colonic backflow is the:
Correct Answer: B (Ileocecal valve)
The ileocecal valve/sphincter regulates the exit of chyme from the ileum and prevents back-migration of fecal colonic bacteria into the small intestine.
The ileocecal valve/sphincter regulates the exit of chyme from the ileum and prevents back-migration of fecal colonic bacteria into the small intestine.
77. The brush-border enzyme maltase breaks down maltose into:
Correct Answer: A (Two molecules of D-glucose)
Maltase hydrolyzes the alpha(1→4) glycosidic linkage of maltose, yielding two identical D-glucose monosaccharides.
Maltase hydrolyzes the alpha(1→4) glycosidic linkage of maltose, yielding two identical D-glucose monosaccharides.
78. Sucrase converts common sucrose (table sugar) into:
Correct Answer: B (Glucose + Fructose)
Sucrase (invertase) breaks sucrose down into its constituent monosaccharides: alpha-D-glucose and beta-D-fructose.
Sucrase (invertase) breaks sucrose down into its constituent monosaccharides: alpha-D-glucose and beta-D-fructose.
79. Which of the following cells release histamine in the gastric mucosa to stimulate acid secretion?
Correct Answer: A (Enterochromaffin-like (ECL) cells)
ECL cells release histamine in response to gastrin and acetylcholine, binding parietal cell H2 receptors to drive HCl release.
ECL cells release histamine in response to gastrin and acetylcholine, binding parietal cell H2 receptors to drive HCl release.
80. Somatostatin, which exerts a universal inhibitory effect on gastrointestinal secretions, is secreted by:
Correct Answer: C (D-cells)
D-cells in the stomach, intestine, and pancreatic islets secrete somatostatin (GHIH), which downregulates gastrin, secretin, and insulin secretion.
D-cells in the stomach, intestine, and pancreatic islets secrete somatostatin (GHIH), which downregulates gastrin, secretin, and insulin secretion.
81. The shortest, widest, and most fixed C-shaped loop of the small intestine is the:
Correct Answer: A (Duodenum)
The duodenum is approximately 25 cm long, retroperitoneal, and wraps around the head of the pancreas in a C-shaped curve.
The duodenum is approximately 25 cm long, retroperitoneal, and wraps around the head of the pancreas in a C-shaped curve.
82. The middle, coiled, highly vascular portion of the small intestine specialized for absorption is the:
Correct Answer: B (Jejunum)
The jejunum measures roughly 2.5 meters, characterized by tall plicae circulares and dense villi for nutrient assimilation.
The jejunum measures roughly 2.5 meters, characterized by tall plicae circulares and dense villi for nutrient assimilation.
83. Water and electrolyte reabsorption from undigested waste occurs predominantly in the:
Correct Answer: C (Large intestine (Colon))
While the small intestine absorbs the bulk of fluid volume, the colon absorbs the remaining water and electrolytes, converting liquid chyme into semisolid feces.
While the small intestine absorbs the bulk of fluid volume, the colon absorbs the remaining water and electrolytes, converting liquid chyme into semisolid feces.
84. The tongue is anchored to the floor of the oral cavity by a midline mucous membrane fold named the:
Correct Answer: A (Lingual frenulum)
The lingual frenulum is the vertical mucosal tether connecting the ventral tongue midline to the sublingual oral floor.
The lingual frenulum is the vertical mucosal tether connecting the ventral tongue midline to the sublingual oral floor.
85. The large V-shaped row of papillae situated at the base of the human tongue are the:
Correct Answer: C (Vallate (Circumvallate) papillae)
Circumvallate papillae (8–12 in number) form an inverted V-shape anterior to the sulcus terminalis and house numerous taste buds.
Circumvallate papillae (8–12 in number) form an inverted V-shape anterior to the sulcus terminalis and house numerous taste buds.
86. Which lingual papillae are most numerous on the tongue but lack taste buds?
Correct Answer: A (Filiform papillae)
Filiform papillae are small, keratinized conical projections that provide abrasive texture for manipulating food but contain no gustatory buds.
Filiform papillae are small, keratinized conical projections that provide abrasive texture for manipulating food but contain no gustatory buds.
87. The anatomical region where the esophagus joins the stomach is termed the:
Correct Answer: A (Cardia (Cardiac region))
The cardia is the superior inlet of the stomach immediately surrounding the gastroesophageal junction.
The cardia is the superior inlet of the stomach immediately surrounding the gastroesophageal junction.
88. The dome-shaped gastric zone projecting superiorly above the cardiac orifice is the:
Correct Answer: B (Fundus)
The fundus is the dome-shaped upper gastric pouch situated to the left of the cardia, often accumulating swallowed air and gas.
The fundus is the dome-shaped upper gastric pouch situated to the left of the cardia, often accumulating swallowed air and gas.
89. The serosa covering abdominal organs is also known as the:
Correct Answer: B (Visceral peritoneum)
The outermost serous coat (serosa) of intraperitoneal organs consists of simple squamous mesothelium, forming the visceral peritoneum.
The outermost serous coat (serosa) of intraperitoneal organs consists of simple squamous mesothelium, forming the visceral peritoneum.
90. Deficiency of Vitamin D or impaired calcium absorption causes which bone disorder in children?
Correct Answer: B (Rickets)
Deficiency of vitamin D impairs gastrointestinal calcium/phosphate uptake, causing incomplete bone matrix mineralization (rickets) in growing children.
Deficiency of vitamin D impairs gastrointestinal calcium/phosphate uptake, causing incomplete bone matrix mineralization (rickets) in growing children.
91. What is the active form of Vitamin D synthesized after renal hydroxylation?
Correct Answer: C (Calcitriol (1,25-(OH)2 D3))
Calcitriol (1,25-dihydroxycholecalciferol) is the active hormone that upregulates calbindin synthesis in enterocytes to boost calcium absorption.
Calcitriol (1,25-dihydroxycholecalciferol) is the active hormone that upregulates calbindin synthesis in enterocytes to boost calcium absorption.
92. Which enzyme in human saliva exerts antibacterial defense by breaking peptidoglycan cell walls?
Correct Answer: A (Lysozyme)
Salivary lysozyme cleaves beta(1→4) bonds between N-acetylmuramic acid and N-acetylglucosamine in bacterial cell walls.
Salivary lysozyme cleaves beta(1→4) bonds between N-acetylmuramic acid and N-acetylglucosamine in bacterial cell walls.
93. The physiological condition known as constipation is caused by:
Correct Answer: A (Decreased colonic motility leading to excessive water absorption)
In constipation, delayed colonic transit allows prolonged fluid extraction by colonocytes, resulting in dry, hard fecal matter.
In constipation, delayed colonic transit allows prolonged fluid extraction by colonocytes, resulting in dry, hard fecal matter.
94. Inflammation of the gastrointestinal tract due to bacterial or viral infection is termed:
Correct Answer: C (Gastroenteritis)
Gastroenteritis is the inflammation of the mucous lining of both the stomach and intestines, commonly presenting with diarrhea, cramps, and nausea.
Gastroenteritis is the inflammation of the mucous lining of both the stomach and intestines, commonly presenting with diarrhea, cramps, and nausea.
95. The non-pathological semi-fluid mass of partially digested food expelled from the stomach into the duodenum is called:
Correct Answer: B (Chyme)
Food masticated and mixed with saliva in the mouth is a ‘bolus’, which is transformed by gastric churning and acid digestion into acidic ‘chyme’.
Food masticated and mixed with saliva in the mouth is a ‘bolus’, which is transformed by gastric churning and acid digestion into acidic ‘chyme’.
96. The milky fluid consisting of lymph and emulsified fat absorbed into lacteals is called:
Correct Answer: B (Chyle)
Chyle is the alkaline lymphatic fluid laden with suspended chylomicrons formed in the lacteals of the small intestine during fat absorption.
Chyle is the alkaline lymphatic fluid laden with suspended chylomicrons formed in the lacteals of the small intestine during fat absorption.
97. Dental formula for a 17-year-old human adolescent with incomplete third molar eruption is:
Correct Answer: B (2122/2122)
Before the eruption of the third molars (wisdom teeth, which appear between ages 17–25), each quadrant contains 2 incisors, 1 canine, 2 premolars, and 2 molars (total 28 teeth).
Before the eruption of the third molars (wisdom teeth, which appear between ages 17–25), each quadrant contains 2 incisors, 1 canine, 2 premolars, and 2 molars (total 28 teeth).
98. Which enzyme hydrolyzes terminal peptide bonds at the amino-terminus of oligopeptides?
Correct Answer: B (Aminopeptidase)
Aminopeptidases are brush-border exopeptidases that sequentially cleave amino acid residues starting from the free N-terminal end of peptides.
Aminopeptidases are brush-border exopeptidases that sequentially cleave amino acid residues starting from the free N-terminal end of peptides.
99. Which portion of the human gastrointestinal tract harbors the densest population of normal commensal microbiota?
Correct Answer: D (Large intestine (Cecum/Colon))
The colon harbors roughly 10¹¹ to 10¹² microorganisms per gram of luminal content, forming the primary microbial ecosystem of the body.
The colon harbors roughly 10¹¹ to 10¹² microorganisms per gram of luminal content, forming the primary microbial ecosystem of the body.
100. Deglutition is a physiological reflex involving:
Correct Answer: B (The act of swallowing the food bolus into the esophagus)
Deglutition is the complete biological act of swallowing, consisting of a voluntary oral phase followed by involuntary pharyngeal and esophageal stages.
Deglutition is the complete biological act of swallowing, consisting of a voluntary oral phase followed by involuntary pharyngeal and esophageal stages.