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Quizzes > Health & Medicine

Digestive System Questions with Answers: 20-Question Quiz

Quick, free digestion practice test with instant results and clear answers.

Editorial: Review CompletedCreated By: Tanin SrivaraphongUpdated Aug 27, 2025
Difficulty: Moderate
2-5mins
Learning OutcomesCheat Sheet
Paper art digestive organs and enzymes on teal background for free 20 question human digestion quiz with answers

This digestive system quiz helps you check how food moves, breaks down, and gets absorbed across the GI tract. Work through 20 questions with clear answers, then keep learning with our digestive system terms, try a focused gastrointestinal nclex quiz, or explore wider anatomy with organ trivia questions.

Easy
What is the primary function of the digestive system?
Pump blood to tissues
Transmit nerve impulses
Exchange gases in lungs
Break down food into nutrients
The digestive system mechanically and chemically breaks down food into nutrients like proteins, carbohydrates, and fats, which are then absorbed to fuel bodily functions. It begins in the mouth with chewing and continues throughout the gastrointestinal tract. Other systems like the circulatory and respiratory have different primary roles.
Which organ is responsible for most nutrient absorption?
Large intestine
Pancreas
Small intestine
Stomach
The small intestine, particularly the jejunum, has a large absorptive surface area due to villi and microvilli structures, allowing efficient nutrient uptake. The stomach primarily digests food, and the large intestine absorbs water and electrolytes.
Where does protein digestion begin?
Stomach
Esophagus
Small intestine
Mouth
Protein digestion begins in the stomach, where pepsinogen is converted to pepsin by stomach acid and starts breaking proteins into peptides. Further digestion occurs in the small intestine by pancreatic proteases.
Which organ produces bile?
Pancreas
Liver
Gallbladder
Spleen
The liver synthesizes bile, which contains bile salts that emulsify fats. The gallbladder stores and concentrates bile but does not produce it.
Which enzyme breaks down carbohydrates in the mouth?
Trypsin
Pepsin
Salivary amylase
Lipase
Salivary amylase (ptyalin), secreted by salivary glands, begins starch digestion into maltose and dextrins in the mouth at a neutral pH. Other enzymes act later in the GI tract.
What is the role of the esophagus?
Concentrate bile
Transport food to the stomach
Secrete digestive enzymes
Absorb nutrients
The esophagus is a muscular tube that propels swallowed food boluses from the pharynx to the stomach via peristalsis. It does not digest food or absorb nutrients.
Where is hydrochloric acid secreted?
Goblet cells of the intestine
Pancreatic acinar cells
Chief cells of the stomach
Parietal cells of the stomach
Parietal cells in the gastric glands secrete hydrochloric acid, which lowers stomach pH for protein denaturation and activation of pepsinogen to pepsin. Chief cells secrete pepsinogen itself.
Which sphincter controls food passage from the stomach to the small intestine?
Anal sphincter
Pyloric sphincter
Ileocecal valve
Lower esophageal sphincter
The pyloric sphincter regulates chyme passage from the stomach into the duodenum and prevents backflow, controlling the rate of gastric emptying.
Medium
What is the main function of the ileum?
Storage of fecal matter
Mechanical breakdown of food
Secretion of digestive enzymes
Absorption of vitamin B12 and bile salts
The ileum is specialized for absorbing vitamin B12 bound to intrinsic factor and for reabsorbing bile salts, which return to the liver via enterohepatic circulation.
Which cells secrete pepsinogen?
Goblet cells
Parietal cells
Chief cells
Enteroendocrine cells
Chief cells, also known as zymogenic cells in the gastric glands, secrete pepsinogen, which is activated to pepsin by stomach acid. Parietal cells secrete acid and intrinsic factor.
What is the function of bile salts?
Emulsify fats for digestion
Hydrolyze carbohydrates
Digest proteins
Buffer stomach acid
Bile salts are amphipathic molecules that emulsify large fat droplets into smaller ones, increasing the surface area for pancreatic lipase to act upon and facilitating lipid digestion.
Which hormone stimulates pancreatic enzyme secretion?
Insulin
Secretin
Cholecystokinin
Gastrin
Cholecystokinin (CCK) is released by I cells in the duodenum in response to fats and amino acids, stimulating the pancreas to secrete digestive enzymes and causing gallbladder contraction.
Where are most vitamins absorbed?
Stomach
Liver
Large intestine
Small intestine
The small intestine is the primary site for absorption of both fat-soluble (A, D, E, K) and water-soluble (B-complex, C) vitamins due to its extensive surface area and specialized transport mechanisms.
Which structure increases surface area in the small intestine?
Microvilli
Crypts of Lieberkühn
Peyer's patches
Lacteals
Microvilli form the brush border on enterocytes and greatly increase the absorptive surface area of the small intestine, facilitating nutrient uptake through enzymes and transporters located on their membranes.
Which enzyme digests fats in the small intestine?
Lactase
Amylase
Pancreatic lipase
Pepsin
Pancreatic lipase, secreted into the duodenum, hydrolyzes dietary triglycerides into monoglycerides and free fatty acids for absorption by enterocytes. Other lipases act earlier or in different contexts.
What is the role of the large intestine?
Absorb water and electrolytes
Produce bile
Digest proteins
Secrete digestive hormones
The large intestine primarily absorbs water and electrolytes from chyme, compacts waste into feces, and hosts bacterial fermentation that produces certain vitamins and short-chain fatty acids.
Hard
What is the role of cholecystokinin (CCK)?
Stimulate bile acid synthesis
Increase gastric acid secretion
Stimulate pancreatic enzyme secretion and gallbladder contraction
Inhibit insulin release
CCK is secreted by duodenal I cells in response to fats and proteins, stimulating pancreatic enzyme secretion, gallbladder contraction, and slowing gastric emptying. It does not directly increase acid secretion or bile synthesis.
How is intrinsic factor important?
It emulsifies fats
It binds vitamin B12 for absorption in the ileum
It neutralizes stomach acid
It activates pepsinogen
Intrinsic factor, secreted by parietal cells, binds vitamin B12 and protects it from degradation, enabling its absorption in the terminal ileum via specific receptors.
Which transporter is responsible for glucose absorption in enterocytes?
SGLT1
CFTR
GLUT2
Na+/K+ ATPase
SGLT1 on the apical membrane of enterocytes co-transports glucose and galactose with sodium down the sodium gradient. GLUT2 on the basolateral membrane then facilitates glucose exit into the bloodstream.
What is the function of enterohepatic circulation?
Deliver hormones to the pancreas
Recycle bile salts from ileum to liver
Move lymph to the bloodstream
Transport amino acids to hepatocytes
Enterohepatic circulation recycles bile salts by absorbing them in the ileum and returning them via the portal vein to the liver, conserving bile components and aiding fat digestion.
Which gut hormone slows gastric emptying?
Somatostatin
Secretin
Motilin
Ghrelin
Somatostatin, produced by D cells in the stomach and intestine, inhibits gastric motility and secretion, including slowing of gastric emptying. Ghrelin and motilin have opposite effects.
How does the gut microbiome assist digestion?
Secretes pepsinogen
Produces intrinsic factor
Emulsifies fats
Ferments undigested carbohydrates into short-chain fatty acids
Gut bacteria ferment non-absorbable carbohydrates to produce short-chain fatty acids like acetate and butyrate, which serve as energy sources for colonocytes and influence host metabolism.
Which zymogen is activated by enteropeptidase?
Chymotrypsinogen
Prolipase
Pepsinogen
Trypsinogen
Enteropeptidase on the duodenal brush border cleaves trypsinogen into active trypsin, which then activates other pancreatic zymogens like chymotrypsinogen. Pepsinogen is activated by low pH, not enteropeptidase.
Which lipase is produced by the pancreas?
Pancreatic lipase
Lipoprotein lipase
Lingual lipase
Hormone-sensitive lipase
Pancreatic lipase is secreted by the pancreas into the small intestine and is the primary enzyme for dietary triglyceride hydrolysis. Lingual lipase acts in the mouth and stomach.
Expert
What is the mechanism of acid secretion in parietal cells?
H+/K+ ATPase proton pump activity
K+ channel opening
Cl-/HCO3- antiporter
Na+/H+ exchanger
Parietal cells secrete gastric acid via the H+/K+ ATPase proton pump on the apical membrane, exchanging intracellular H+ for extracellular K+. Carbonic anhydrase generates the H+ and HCO3- required for this process.
How does the sodium-dependent bile acid transporter (ASBT) function?
Diffuses unconjugated bile acids passively
Exchanges bile acids for Cl- in the colon
Co-transports bile acids with Na+ across the apical membrane of ileal enterocytes
Secretes bile acids from hepatocytes into bile canaliculi
ASBT on the apical membrane of ileal enterocytes uses the sodium gradient to actively transport conjugated bile acids from the lumen into cells for recycling via the portal circulation.
What is the role of the migrating motor complex?
Sweep residual food and secretions through the GI tract during fasting
Generate peristalsis during a meal
Control sphincter of Oddi activity
Stimulate mucus secretion
The migrating motor complex is a cyclic motility pattern during the interdigestive phase that clears undigested materials and secretions, helping prevent bacterial overgrowth. It pauses upon food ingestion.
Which inhibitory neurotransmitter regulates villus contractility?
Acetylcholine
Substance P
Nitric oxide
Serotonin
Nitric oxide released by enteric inhibitory neurons causes relaxation of intestinal smooth muscle, regulating villus and intestinal contractility and modulating blood flow. Other neurotransmitters are excitatory.
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Study Outcomes

  1. Understand digestive anatomy -

    Recognize the major organs of the human digestive system and their spatial relationships, helping you map the pathway food follows through the body.

  2. Identify organ functions -

    Define the specific roles each digestive organ plays in breaking down and processing food, from ingestion to nutrient absorption.

  3. Explain enzymatic roles -

    Describe how key digestive enzymes and secretions contribute to chemical digestion and nutrient breakdown.

  4. Trace the food passage -

    Outline the sequential stages of food movement and transformation, following its journey from the mouth to elimination.

  5. Differentiate digestion processes -

    Contrast mechanical and chemical digestion, highlighting how each process works together to convert food into usable nutrients.

  6. Apply quiz strategies -

    Use your understanding of organs, enzymes, and processes to confidently tackle and answer 20 questions about the digestive system with answers.

Cheat Sheet

  1. Major organ pathway -

    When tackling 20 questions about the digestive system with answers, start by mapping the tract from the mouth through the esophagus, stomach, small intestine, and large intestine. Use the mnemonic "My Elephant Sees Small Iguanas" to recall Mouth, Esophagus, Stomach, Small intestine, and Large intestine. Each segment has specialized roles in mechanical and chemical digestion (University of Cambridge).

  2. Key digestive enzymes -

    Remember that salivary amylase breaks starch into maltose, pepsin cleaves proteins into peptides in the stomach, and pancreatic lipase hydrolyzes fats into fatty acids (NIH). A quick formula chart - Starch + Amylase → Maltose; Protein + Pepsin → Peptides - helps in any digestive system quiz question. Note each enzyme's optimal pH for maximal activity.

  3. pH environments -

    The stomach's acidic pH (~1.5 - 3.5) activates pepsin and kills microbes, while the small intestine's alkaline pH (~7.5 - 8.5) optimizes pancreatic enzymes (Harvard Health). Link pH zones to function when you practice human digestive system quiz scenarios. Remember: "Acid in the stomach, base in the bowels."

  4. Mechanical vs. chemical digestion -

    Mechanical digestion involves chewing and stomach churning to increase food surface area, whereas chemical digestion uses enzymes and bile to break macromolecules (Mayo Clinic). In a digestive system practice quiz, distinguish peristalsis from hydrolysis reactions. A good tip: visualize kneading dough for mechanical and dissolving sugar for chemical.

  5. Absorption and surface area -

    The small intestine's villi and microvilli create a surface area roughly the size of a tennis court (~200 m²), maximizing nutrient uptake (Johns Hopkins Medicine). Focus on how monosaccharides, amino acids, and lipids enter blood or lymph vessels during a grade 6 digestive system test. Remember: "Villi = Victory for nutrients."

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