60 free MCQs on Digestion and Absorption with worked answers and explanations. The digestive tract, digestive enzymes, hormonal control of digestion, and liver function. High NEET weightage.
Take the timed Digestion and Absorption chapterwise test →Below are 60 practice questions on Digestion and Absorption, sorted Easy → Hard. Tap “Show answer & explanation” under any question to check yourself. Want the full theory first? Read the Digestion and Absorption notes.
The human digestive system. Image: LadyofHats (Mariana Ruiz), Public Domain, via Wikimedia Commons.
Q1.
Which enzyme begins protein digestion in the stomach?
Answer: B. Pepsin
Why: Pepsin is the main protein-digesting enzyme in the stomach. It is activated from pepsinogen by HCl.
Q2.
The main site of digestion and absorption is the:
Answer: C. Small intestine
Why: Most chemical digestion and nutrient absorption occurs in the small intestine (duodenum, jejunum, ileum) via villi.
Q3.
Bile is produced by the _____ and stored in the _____:
Answer: B. Liver, gall bladder
Why: Bile is produced by the liver and stored in the gall bladder. It emulsifies (breaks up) fat droplets for digestion.
Q4.
The enzyme salivary amylase digests:
Answer: C. Starch (carbohydrates)
Why: Salivary amylase in saliva begins digestion of starch (polysaccharide) in the mouth, breaking it into maltose.
Q5.
The wave-like muscular contractions that move food along the alimentary canal are called:
Answer: C. Peristalsis
Why: Peristalsis refers to the rhythmic contraction and relaxation of muscles in the gut wall that pushes food forward through the digestive tract.
Q6.
Pepsinogen, the inactive precursor of pepsin, is secreted by cells of the:
Answer: D. Gastric glands
Why: Peptic (chief) cells of gastric glands secrete pepsinogen, which is converted to active pepsin by hydrochloric acid in the stomach.
Q7.
The pancreas releases digestive enzymes into the small intestine through the:
Answer: A. Pancreatic duct
Why: Pancreatic juice, containing enzymes like trypsin, amylase and lipase, reaches the duodenum through the pancreatic duct.
Q8.
Finger-like projections that increase the surface area of the small intestine for absorption are called:
Answer: A. Villi
Why: Villi are tiny finger-like projections of the intestinal lining that greatly increase surface area for the absorption of digested nutrients.
Q9.
The undigested and unabsorbed remains of food are eliminated from the body through a process called:
Answer: C. Egestion
Why: Egestion is the elimination of undigested, unabsorbed food residue as faeces through the anus.
Q10.
Bile, though it contains no digestive enzymes, helps in fat digestion mainly by:
Answer: D. Emulsifying fat globules to raise the surface area for lipase
Why: Bile salts emulsify large fat globules into smaller droplets, increasing the surface area available for pancreatic lipase to act upon.
Q11.
The breakdown of complex food into simpler, absorbable substances is called:
Answer: A. digestion
Why: Digestion converts large food molecules into small absorbable ones.
Q12.
The digestion of starch begins in the:
Answer: A. mouth
Why: Salivary amylase in the mouth starts starch digestion.
Q13.
The enzyme in saliva that acts on starch is:
Answer: A. salivary amylase
Why: Salivary amylase (ptyalin) breaks starch into maltose.
Q14.
The muscular organ where food is churned with gastric juice is the:
Answer: A. stomach
Why: The stomach mixes food with acidic gastric juice.
Q15.
Most of the absorption of digested food takes place in the:
Answer: A. small intestine
Why: The small intestine, with its villi, is the main site of absorption.
Q16.
The largest gland in the human body is the:
Answer: A. liver
Why: The liver is the largest gland; it produces bile.
Q17.
Bile is produced by the:
Answer: A. liver
Why: The liver secretes bile, which aids fat digestion.
Q18.
The finger-like projections that increase the absorptive surface of the small intestine are the:
Answer: A. villi
Why: Villi greatly increase the surface area for absorption.
Q19.
Water from the food residue is mainly absorbed in the:
Answer: A. large intestine
Why: The large intestine reabsorbs water, concentrating the waste.
Q20.
The front teeth used for cutting and biting food are the:
Answer: A. incisors
Why: Incisors are the sharp cutting teeth at the front.
Q21.
Peristalsis is the movement of:
Answer: B. Food through the digestive tract by rhythmic muscle contractions
Why: Peristalsis: coordinated, rhythmic smooth muscle contractions that propel food through the gastrointestinal tract.
Q22.
The portal vein carries blood from:
Answer: B. Intestines (nutrient-rich blood) to liver for processing
Why: Hepatic portal vein: carries nutrient-rich blood from digestive organs (stomach, intestines) directly to the liver for metabolism.
Q23.
Conjugation of bilirubin in the liver involves:
Answer: B. Attachment to glucuronic acid for water-solubility and bile excretion
Why: Bilirubin (from RBC breakdown) is conjugated with glucuronic acid in liver (becoming water-soluble), excreted in bile, and gives feces brown color.
Q24.
Secretin hormone from the duodenum stimulates the pancreas to:
Answer: B. Secrete bicarbonate juice to neutralize stomach acid
Why: Secretin: released by S cells in duodenum when acid enters. Stimulates pancreas to secrete bicarbonate (NaHCO3) to neutralize HCl.
Q25.
The main role of the large intestine is:
Answer: C. Water and electrolyte reabsorption
Why: The large intestine (colon) primarily reabsorbs water and electrolytes from indigestible food, forming feces. Gut bacteria also produce some vitamins.
Q26.
Salivary amylase begins the digestion of starch in the mouth, breaking it down into:
Answer: B. Maltose and smaller polysaccharides
Why: Salivary amylase hydrolyzes starch into smaller polysaccharides and maltose, though this digestion is incomplete since the enzyme is inactivated by stomach acid.
Q27.
Which accessory organ of digestion produces bile, which is then stored and concentrated in the gall bladder?
Answer: D. Liver
Why: The liver continuously produces bile, which is stored and concentrated in the gall bladder until needed for fat digestion in the duodenum.
Q28.
In the stomach, pepsin acts optimally in a highly acidic environment maintained mainly by secretions from:
Answer: B. Parietal cells, which secrete hydrochloric acid
Why: Parietal cells of the gastric glands secrete hydrochloric acid, creating the highly acidic environment in which pepsin can act effectively on proteins.
Q29.
Villi and microvilli in the small intestine primarily function to:
Answer: C. Increase the surface area available for absorption of digested food
Why: Villi (finger-like projections) and microvilli (on individual epithelial cells) greatly increase the surface area of the small intestine, enhancing absorption of digested nutrients.
Q30.
Following protein digestion, the resulting amino acids are mainly absorbed into the:
Answer: C. Blood capillaries within the intestinal villi
Why: Amino acids, being water-soluble, are absorbed into the blood capillaries of the villi and transported via the hepatic portal vein to the liver, unlike fats, which are absorbed into lacteals.
Q31.
In the stomach, the enzyme pepsin digests:
Answer: A. proteins
Why: Pepsin breaks proteins into smaller peptides in the acidic stomach.
Q32.
Bile secreted by the liver is stored in the:
Answer: A. gall bladder
Why: Bile is stored and concentrated in the gall bladder.
Q33.
The pancreatic enzyme that digests fats is:
Answer: A. lipase
Why: Pancreatic lipase breaks fats into fatty acids and glycerol.
Q34.
The acid present in gastric juice is:
Answer: A. hydrochloric acid
Why: The stomach secretes hydrochloric acid, activating pepsin and killing microbes.
Q35.
The final products of protein digestion are:
Answer: A. amino acids
Why: Proteins are digested completely into amino acids.
Q36.
The final products of carbohydrate digestion are:
Answer: A. simple sugars
Why: Carbohydrates are broken down into simple sugars such as glucose.
Q37.
Bile aids fat digestion by breaking large fat globules into smaller ones, a process called:
Answer: A. emulsification
Why: Emulsification increases the surface area of fats for lipase to act on.
Q38.
The muscular tube that carries food from the mouth to the stomach is the:
Answer: A. oesophagus
Why: The oesophagus (food pipe) conducts food to the stomach.
Q39.
The region of the alimentary canal immediately after the stomach is the:
Answer: A. small intestine
Why: Food passes from the stomach into the small intestine.
Q40.
The wave-like muscular contractions that push food along the gut are called:
Answer: A. peristalsis
Why: Peristalsis is the rhythmic muscular movement that propels food.
Q41.
Cholecystokinin (CCK) is released from I-cells of duodenum in response to:
Answer: B. Fat and protein in duodenum; it stimulates pancreatic enzyme secretion and gall bladder contraction
Why: CCK: released by duodenal I-cells when fat and protein enter. Stimulates pancreatic acinar cells (enzymes: lipase, protease), gall bladder contraction, and hepatic bile secretion.
Q42.
The hepatic first-pass effect refers to:
Answer: B. Orally ingested drugs being metabolized by the gut wall and liver before reaching systemic circulation, reducing bioavailability
Why: First-pass metabolism: drugs absorbed from intestine enter portal circulation, passing through liver before reaching systemic circulation. Liver enzymes (CYP450) metabolize the drug, often significantly reducing bioavailability.
Q43.
Trypsinogen secreted by the pancreas is activated to trypsin in the duodenum by:
Answer: C. Enterokinase, an enzyme produced by the intestinal mucosa
Why: Enterokinase, secreted by the duodenal mucosa, cleaves trypsinogen into active trypsin, which then activates other pancreatic zymogens in a cascade.
Q44.
Bile salts aid fat digestion mainly by:
Answer: B. Emulsifying large fat globules into smaller droplets, increasing surface area for lipase action
Why: Bile salts emulsify fats, breaking large globules into smaller droplets and increasing the surface area available for pancreatic lipase to act on.
Q45.
Most digested monosaccharides and amino acids are absorbed from the small intestine into the blood by:
Answer: C. Active, energy-dependent transport across the intestinal epithelium
Why: Glucose and amino acids are largely absorbed by active transport (often coupled to sodium ion gradients) across the intestinal mucosa, allowing absorption even against a concentration gradient.
Q46.
Gastrin secreted by G-cells of the stomach mucosa primarily stimulates:
Answer: C. Secretion of HCl and pepsinogen by gastric glands
Why: Gastrin stimulates gastric glands to secrete HCl and pepsinogen, and also promotes gastric motility, aiding protein digestion in the stomach.
Q47.
Why is pepsinogen secreted as an inactive zymogen rather than as active pepsin?
Answer: B. It prevents the enzyme from digesting the stomach's own protein-rich gastric lining before reaching the lumen
Why: Secreting pepsin as inactive pepsinogen protects the stomach's own epithelial lining from autodigestion; HCl converts pepsinogen to active pepsin only within the gastric lumen.
Q48.
Vitamin B12 absorption in the ileum specifically requires:
Answer: C. Binding to intrinsic factor secreted by gastric parietal cells
Why: Vitamin B12 must bind intrinsic factor, secreted by gastric parietal cells, to form a complex that is recognized and absorbed by specific receptors in the ileum.
Q49.
Chyme entering the duodenum from the stomach is strongly acidic. Its pH is raised mainly by:
Answer: D. Bicarbonate ions secreted in pancreatic juice
Why: Pancreatic juice is rich in bicarbonate ions, which neutralize the acidic chyme as it enters the duodenum, creating a suitable pH for pancreatic enzyme activity.
Q50.
Lacteals present in the villi of the small intestine are primarily responsible for absorbing:
Answer: B. Digested fats in the form of chylomicrons
Why: Lacteals are lymphatic capillaries within intestinal villi that absorb chylomicrons (packaged triglycerides) formed after fat digestion, transporting them via lymph before they enter the blood.
Q51.
Trypsin, an enzyme secreted by the pancreas, digests:
Answer: A. proteins
Why: Trypsin continues protein digestion in the small intestine.
Q52.
The inactive precursor of the enzyme pepsin, secreted by the stomach, is:
Answer: A. pepsinogen
Why: Pepsinogen is converted to active pepsin by hydrochloric acid.
Q53.
Vitamins that are absorbed along with dietary fats and bile salts are the ___ vitamins:
Answer: A. fat-soluble
Why: Fat-soluble vitamins (A, D, E, K) are absorbed with fats.
Q54.
The enzyme that curdles milk protein (casein) in infants is:
Answer: A. rennin
Why: Rennin coagulates milk in the infant stomach for digestion.
Q55.
Assimilation refers to the ___ of absorbed nutrients by body cells:
Answer: A. utilisation
Why: Assimilation is the use of absorbed nutrients for energy, growth and repair.
Q56.
Absorbed glucose and amino acids enter the bloodstream through the:
Answer: A. capillaries in the villi
Why: Water-soluble nutrients pass into the blood capillaries of the villi.
Q57.
The hormone that stimulates the secretion of gastric juice is:
Answer: A. gastrin
Why: Gastrin stimulates the stomach to release gastric juice.
Q58.
The vermiform appendix, a vestigial structure in humans, is attached to the:
Answer: A. caecum of the large intestine
Why: The appendix projects from the caecum at the start of the large intestine.
Q59.
The dental formula of an adult human is:
Answer: A. 2123/2123
Why: Each half-jaw has 2 incisors, 1 canine, 2 premolars and 3 molars: 2123/2123.
Q60.
Egestion, the removal of undigested faecal matter, takes place through the:
Answer: A. anus
Why: Undigested waste leaves the body through the anus.