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Digestion/Nutrition Past Papers
Solved past paper MCQs for Digestion/Nutrition from official UHS, NUMS, SZABMU, DUHS, and KMU examinations. Includes verified distractor autopsies and step-by-step cognitive explanations.
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Official printable A4 booklet containing all 42 verified past paper MCQs with unbroken options, 5-column rapid answer key, and Propolis cognitive error autopsies.
The leaf is bilobed with midrib and a row of long stiff bristles along the margins of leaf is present in:
A
Drosera intermedia
B
Dionaea muscipula
C
Sarracenia purpurea
D
Nepenthes purpurea
View Answer & Propolis Autopsy
Correct Key: Option BDiagnostic Explanation
Concept:
Different carnivorous plants use entirely different mechanical structures to trap prey.
Formula:
N/A
Solution:
The description of a "bilobed leaf with a midrib and a row of long stiff bristles (teeth) along the margins" perfectly describes the active snap-trap mechanism.
This specific morphology belongs to the Venus flytrap, scientifically known as Dionaea muscipula.
Why other options are incorrect:
Drosera (sundew) uses sticky mucilage tentacles. Sarracenia and Nepenthes are pitcher plants that use deep, fluid-filled tubular leaves as passive pitfall traps.
Which of the following salivary gland is present behind the jaws?
A
Sublingual
B
Sub-maxillary
C
Maxillary
D
Parotid
View Answer & Propolis Autopsy
Correct Key: Option BDiagnostic Explanation
Concept:
The major salivary glands are named anatomically based on their exact location relative to facial and oral structures.
Formula:
N/A
Solution:
The Sub-maxillary glands (also interchangeably called Submandibular glands) are situated beneath the floor of the mouth, wrapping around the inner side and slightly behind the lower jawbone (mandible).
Why other options are incorrect:
The Parotid glands are located prominently in front of and just below the ears. The Sublingual glands are located far forward directly under the tongue. "Maxillary" is not a standard major salivary gland.
Bile contains high concentrations of lipids. If the delicate ratio of bile components shifts, these lipids can fall out of solution and crystallize.
Formula:
N/A
Solution:
The liver continuously excretes cholesterol into bile.
Bile salts usually act as solvents to keep this cholesterol dissolved.
If there is a hypersecretion of cholesterol or a deficit in bile salts, the excess cholesterol precipitates out, forming hard crystalline masses known as gallstones (cholelithiasis).
Why other options are incorrect:
While some gallstones contain bilirubin or trace calcium, the vast majority (over 80%) are fundamentally composed of precipitated cholesterol. Calcium phosphate stones typically form in the kidneys, not the gallbladder.
At the end of ileum, there is ____ sphincter which opens and closes time to time to allow small amount of residue from ileum to enter the large intestine.
A
Pyloric
B
Cardiac
C
Ileocolic
D
Rectal
View Answer & Propolis Autopsy
Correct Key: Option CDiagnostic Explanation
Concept:
Sphincters act as biological valves throughout the digestive tract to regulate the forward flow of food and prevent backward contamination.
Formula:
N/A
Solution:
The terminal end of the small intestine is the ileum, and the beginning of the large intestine is the colon (specifically the caecum).
The smooth muscle ring situated exactly at this junction is accurately termed the Ileocolic sphincter (or ileocecal valve).
It opens briefly to drop waste into the colon and closes rapidly to prevent bacteria-rich colonic feces from backflowing into the sterile small intestine.
Why other options are incorrect:
The pyloric sphincter connects the stomach to the duodenum. The cardiac (lower esophageal) sphincter connects the esophagus to the stomach. The rectal (anal) sphincters are at the very end of the digestive tract.
A person with a removed gall bladder experience difficulty in fat digestion due to:
A
Absence of bile
B
Uncontrolled release of bile
C
Reduce alkalinity of bile
D
Absence of bile pigments
View Answer & Propolis Autopsy
Correct Key: Option BDiagnostic Explanation
Concept:
The gallbladder is not a manufacturing organ; it is strictly a storage and concentration reservoir for bile produced by the liver.
Formula:
N/A
Solution:
When the gallbladder is surgically removed (cholecystectomy), the liver still produces bile at a normal rate.
However, without a storage sac to hold and concentrate it until a fatty meal is eaten, the bile drips continuously and uncontrolled into the small intestine.
When a heavy fat meal arrives, there is no large "surge" of concentrated bile available to efficiently emulsify it, leading to poor fat digestion.
Why other options are incorrect:
Bile is absolutely not absent; the liver still makes it. The alkalinity and pigments remain unchanged. The issue is purely the loss of regulated, concentrated delivery.
Digestive juices vary radically in pH to suit the optimal functioning range of their specific enclosed enzymes.
Formula:
N/A
Solution:
Gastric chyme entering the duodenum is highly acidic (pH ~2).
Pancreatic juice contains a massive concentration of bicarbonate ions (\(HCO_3^-\)), which makes it distinctly alkaline.
This alkalinity (with a typical pH around 8.0) neutralizes the incoming acid and creates the perfect basic environment for pancreatic lipases, amylases, and proteases to operate.
Why other options are incorrect:
Values like 0.7 or 0.8 are extremely acidic—more acidic than battery acid or standard stomach acid—and would instantly denature pancreatic enzymes.
Parietal cell → Pepsin: Mismatched pair. Parietal cells secrete \(\text{HCl}\) and intrinsic factor; pepsin is derived from chief cell pepsinogen. Hence, Option C is the mismatched pair.
Why other options are incorrect:
Options A, B, and D represent accurate physiological pairings in human gastrointestinal anatomy.
The splanchnic circulation is responsible for carrying blood away from the digestive organs to the liver via the hepatic portal system.
Formula:
N/A
Solution:
The inferior mesenteric vein specifically drains blood from the distal portions of the Large intestine (colon and rectum).
The superior mesenteric vein drains the small intestine and the proximal part of the large intestine.
Both ultimately converge to form the hepatic portal vein.
Why other options are incorrect:
The stomach is drained primarily by the gastric veins. The gallbladder is drained by the cystic vein. The liver is drained by the hepatic veins directly into the vena cava.
Which Proteolytic enzyme is NOT secreted in inactive form?
A
Chymotrypsin
B
Pepsin
C
Trypsin
D
Erypsin
View Answer & Propolis Autopsy
Correct Key: Option DDiagnostic Explanation
Concept:
Major proteases produced by the stomach and pancreas are secreted as zymogens (inactive) to protect the organs. However, brush-border enzymes are often active immediately.
Formula:
N/A
Solution:
Pepsin is secreted as inactive pepsinogen.
Trypsin is secreted as inactive trypsinogen.
Chymotrypsin is secreted as inactive chymotrypsinogen.
Erepsin (a mixture of peptidases found in intestinal juice) is secreted directly in its active form to immediately process small peptides into single amino acids right at the absorption surface.
Why other options are incorrect:
Options A, B, and C are all classic examples of dangerous endopeptidases that absolutely must be secreted as inactive precursors to avoid self-digestion.
Mastication causes exocrine glands under the tongue and in the back of mouth to secrete a watery liquid called:
A
Bolus
B
Bile
C
Pancreatic Juice
D
Saliva
View Answer & Propolis Autopsy
Correct Key: Option DDiagnostic Explanation
Concept:
Mechanical digestion (chewing) physically stimulates nervous reflexes that activate local exocrine glands in the oral cavity.
Formula:
N/A
Solution:
Mastication (chewing) stimulates the parotid, submandibular, and sublingual glands.
These glands release a watery fluid composed of water, mucus, lysozyme, and amylase, collectively called Saliva.
Saliva lubricates the food, forming it into a swallowable mass.
Why other options are incorrect:
A Bolus is the chewed mass of food mixed with saliva, not the liquid itself. Bile is produced by the liver. Pancreatic juice is produced by the pancreas.
Pepsinogen is converted into its active form pepsin by:
A
Proteolytic enzyme action
B
Dissolving in mucus
C
Hormonal action
D
Hydrochloric acid
View Answer & Propolis Autopsy
Correct Key: Option DDiagnostic Explanation
Concept:
Zymogens require specific environmental conditions or chemical triggers to cleave their inhibitory peptide bonds and become active.
Formula:
N/A
Solution:
In the stomach, parietal cells secrete a highly concentrated solution of Hydrochloric acid (HCl).
This extreme acidity (pH ~2) causes a conformational change in the pepsinogen molecule, allowing it to auto-cleave a small peptide fragment from itself.
This cleavage uncovers the active site, converting the inactive pepsinogen into the active protease pepsin.
Why other options are incorrect:
While active pepsin can activate more pepsinogen (autocatalysis), the initial and primary converter is the highly acidic HCl environment. Hormones (like gastrin) stimulate secretion but do not directly activate the enzyme chemically.
Vitamin B12 is a massive molecule that cannot be absorbed through simple diffusion; it requires a specific binding protein to survive the intestinal tract.
Formula:
N/A
Solution:
The parietal (oxyntic) cells located in the mucosa of the Stomach have a dual function.
Alongside secreting HCl, they synthesize and secrete a glycoprotein called Intrinsic factor.
Intrinsic factor binds to dietary Vitamin B12, protecting it and allowing it to be absorbed much later in the terminal ileum.
Why other options are incorrect:
The pancreas, liver, and duodenum do not produce intrinsic factor. (Lack of intrinsic factor from the stomach leads to pernicious anemia).
Digestion of which food component starts in oral cavity?
A
Proteins
B
Fats
C
Carbohydrates
D
Vitamins
View Answer & Propolis Autopsy
Correct Key: Option CDiagnostic Explanation
Concept:
Enzymatic breakdown is strictly compartmentalized based on the specific enzymes secreted in different regions of the gut.
Formula:
N/A
Solution:
The oral cavity is equipped with salivary glands that secrete salivary amylase (ptyalin).
Amylase is an enzyme designed exclusively to break the glycosidic bonds found in Carbohydrates (specifically starch and glycogen).
Therefore, chemical carbohydrate digestion begins the moment food enters the mouth.
Why other options are incorrect:
Protein digestion begins in the stomach via pepsin. Major fat digestion begins in the small intestine via pancreatic lipase (though minimal lingual lipase exists, carbs are the primary target). Vitamins are generally absorbed intact, not digested.
Which one of the following is not a carnivorous plant?
A
Pitcher plant
B
Sundew
C
Butterworts
D
Money plant
View Answer & Propolis Autopsy
Correct Key: Option DDiagnostic Explanation
Concept:
Carnivorous plants have adapted to grow in nitrogen-deficient soils by trapping and digesting small insects or animals to supplement their nitrogen supply.
Formula:
N/A
Solution:
Pitcher plants (e.g., Sarracenia), Sundew (Drosera), and Butterworts (Pinguicula) possess specialized leaves to trap and digest prey.
The Money plant (Epipremnum aureum) is a standard autotrophic vine that absorbs all its mineral requirements directly from the soil and does not exhibit any carnivorous adaptations.
Why other options are incorrect:
Options A, B, and C are all well-known examples of true carnivorous plants.
While carbohydrate digestion is the main focus in the mouth, a small amount of lipid digestion also initiates there due to specific minor glands.
Formula:
N/A
Solution:
Von Ebner's glands are minor salivary glands located in a moat-like trough surrounding the circumvallate papillae on the posterior surface of the tongue.
These glands secrete lingual lipase, which begins the digestion of dietary triglycerides into fatty acids and diglycerides.
Why other options are incorrect:
Parotid, submandibular, and sub-maxillary glands primarily secrete saliva rich in water, mucin, and salivary amylase, but not lingual lipase.
Bolus enters the esophagus/not the trachea due to presence of:
A
Roof palate
B
Mouth
C
Epiglottis
D
Buccal cavity
View Answer & Propolis Autopsy
Correct Key: Option CDiagnostic Explanation
Concept:
The swallowing mechanism requires a strict separation of the digestive and respiratory pathways at the pharynx.
Formula:
N/A
Solution:
The epiglottis is a leaf-shaped cartilaginous flap situated at the top of the larynx.
During swallowing, it acts as a mechanical lid, closing off the glottis (tracheal opening) so the food bolus slides smoothly into the esophagus.
Why other options are incorrect:
The roof of the palate separates the nasal and oral cavities, while the mouth and buccal cavity are spaces where mastication occurs, not the valve controlling the airway.
Enzymatic portion of gastric juice is secreted by which mucosal cell?
A
Oxyntic cells
B
Chief cells
C
Mucus cells
D
Endocrine cells
View Answer & Propolis Autopsy
Correct Key: Option BDiagnostic Explanation
Concept:
Gastric juice is a mixture of water, mucus, acid, and digestive enzymes.
Formula:
N/A
Solution:
The primary enzymatic component of gastric juice is pepsinogen (the inactive form of the protease pepsin).
This enzyme is synthesized and secreted exclusively by the Chief cells (zymogenic cells) located at the base of the gastric glands.
Why other options are incorrect:
Oxyntic cells secrete HCl (chemical, not enzymatic). Mucus cells secrete mucin. Endocrine cells secrete hormones (like gastrin) into the blood, not enzymes into the gastric lumen.
Select the hormone which increases the activity of parietal and chief cells:
A
Cholecystokinin
B
Secretin
C
Gastrin
D
Acetylcholine
View Answer & Propolis Autopsy
Correct Key: Option CDiagnostic Explanation
Concept:
Gastric secretion is tightly regulated by both neural and hormonal mechanisms triggered by the presence of food.
Formula:
N/A
Solution:
When protein-rich food enters the stomach, specific G-cells in the gastric mucosa are stimulated to release the hormone Gastrin into the bloodstream.
Gastrin circulates back to the stomach wall, potently stimulating parietal cells to release HCl and chief cells to release pepsinogen, thereby ramping up digestive activity.
Why other options are incorrect:
Secretin and Cholecystokinin (CCK) are intestinal hormones that primarily stimulate the pancreas and gallbladder while inhibiting stomach activity. Acetylcholine is a neurotransmitter, not a hormone.
Digested food from intestine is carried to the liver by:
A
Hepatic artery
B
Hepatic vein
C
Hepatic portal vein
D
Hepatic portal artery
View Answer & Propolis Autopsy
Correct Key: Option CDiagnostic Explanation
Concept:
Nutrients absorbed into the bloodstream from the gastrointestinal tract must be processed by the liver before entering the general systemic circulation.
Formula:
N/A
Solution:
The circulatory pathway that directly connects the capillary beds of the intestines to the capillary beds of the liver is the hepatic portal system.
The Hepatic portal vein is the major vessel that collects this nutrient-rich (but deoxygenated) blood from the mesenteric veins and transports it straight into the liver for metabolic processing and detoxification.
Why other options are incorrect:
The hepatic artery brings oxygenated systemic blood to the liver. The hepatic vein carries processed blood away from the liver to the heart. There is no structure called the "hepatic portal artery."
Emulsification of large fat globules is facilitated by:
A
Lipase
B
Bile salts
C
Trypsin
D
Chymotrypsin
View Answer & Propolis Autopsy
Correct Key: Option BDiagnostic Explanation
Concept:
Fats are hydrophobic and tend to clump together in the watery environment of the intestine, severely limiting the surface area available for water-soluble enzymes (lipases) to act upon.
Formula:
N/A
Solution:
Bile salts (such as sodium glycocholate and taurocholate) are amphipathic molecules secreted by the liver.
They act like biological detergents. Their hydrophobic ends bury into the fat droplets, while their hydrophilic ends face outward.
This mechanical dispersion breaks large fat masses into microscopic droplets (micelles), a process known as emulsification.
Why other options are incorrect:
Lipase is the enzyme that actually chemically digests the fat after it is emulsified. Trypsin and Chymotrypsin are proteases that break down proteins, entirely unrelated to fat.
Which of the following is not a component of bile?
A
Digestive enzymes
B
Salts
C
Mucus
D
Lecithin
View Answer & Propolis Autopsy
Correct Key: Option ADiagnostic Explanation
Concept:
Bile is an exocrine secretion of the liver critical for fat digestion, but it operates purely on physical (mechanical) principles rather than chemical hydrolysis.
Formula:
N/A
Solution:
Bile is a complex mixture containing bile salts, cholesterol, bile pigments (bilirubin/biliverdin), lecithin (a phospholipid), and water/mucus.
Crucially, the liver does not produce any digestive enzymes that are secreted into bile.
Bile prepares fat for digestion, but the actual chemical breakdown is done by lipases from the pancreas.
Why other options are incorrect:
Salts (bile salts) and Lecithin are the primary emulsifying agents in bile. Mucus is present for lubrication and protection.
The large intestine (colon) is anatomically divided into sequential segments following the small intestine.
Formula:
N/A
Solution:
Upon exiting the ileum of the small intestine through the ileocolic sphincter, digested material immediately enters a dilated blind pouch.
This very first segment of the large intestine is anatomically known as the Caecum.
Why other options are incorrect:
The ascending colon continues upward from the caecum. The appendix is an attachment to the caecum. The rectum is the final storage chamber before the anus.
During the swallowing reflex, the respiratory tract must be temporarily sealed off to prevent food or liquids from entering the lungs.
Formula:
N/A
Solution:
The epiglottis is a flap of elastic cartilage attached to the entrance of the larynx.
During swallowing, the larynx moves upward, causing the epiglottis to fold flat and cover the glottis (the opening to the trachea).
This physical barrier safely diverts the food bolus down the esophagus.
Why other options are incorrect:
The glottis is the opening itself (which gets covered), cheeks aid in chewing, and the tongue pushes the bolus backward but does not physically block the airway.
Salivary amylase begins to digest starch to shorter polysaccharides and then to:
A
Sucrose
B
Maltose
C
Glucose
D
Lactose
View Answer & Propolis Autopsy
Correct Key: Option BDiagnostic Explanation
Concept:
Amylase specifically targets alpha-1,4-glycosidic linkages in starch molecules.
Formula:
N/A
Solution:
When salivary amylase acts on starch (a large polymer of glucose), it cleaves it into smaller fragments like dextrins, and eventually into the disaccharide maltose.
Complete breakdown to single glucose monomers requires the enzyme maltase, which is located later in the small intestine.
Why other options are incorrect:
Sucrose is table sugar (glucose + fructose), lactose is milk sugar (glucose + galactose), and glucose is the final monomeric product, which amylase cannot produce on its own.
Type of salivary glands found in human oral cavity:
A
3
B
6
C
4
D
2
View Answer & Propolis Autopsy
Correct Key: Option ADiagnostic Explanation
Concept:
Saliva is produced by specialized exocrine glands located in and around the oral cavity.
Formula:
N/A
Solution:
Humans possess exactly 3 major pairs of salivary glands.
They are: 1) Parotid glands (in front of the ears), 2) Submandibular / Sub-maxillary glands (under the jaw), and 3) Sublingual glands (under the tongue).
Why other options are incorrect:
The numbers 2, 4, and 6 do not represent the correct count of distinct major salivary gland types in human anatomy.
Enzyme pepsin acts on which of the following substrate to produce the respective product?
A
Substrate: Proteins → Product: Polypeptides
B
Substrate: Polypeptide → Product: Dipeptides
C
Substrate: Fats → Product: Fatty acids / glycerol
D
Substrate: Proteins → Product: Amino acids
View Answer & Propolis Autopsy
Correct Key: Option ADiagnostic Explanation
Concept:
Pepsin is an endopeptidase that operates in the highly acidic environment of the stomach to begin the chemical breakdown of dietary proteins.
Formula:
N/A
Solution:
Pepsin acts on large, intact Proteins.
It cleaves internal peptide bonds, reducing these massive protein molecules into smaller fragments known as Polypeptides and peptones.
It does not complete the digestion down to individual amino acids.
Why other options are incorrect:
Complete breakdown to dipeptides and free amino acids requires pancreatic enzymes (like trypsin/chymotrypsin) and intestinal brush border peptidases. Fats are digested by lipases, not pepsin.
Following is the structure of gastric glands in stomach wall where 'X' is:
A
Mucosa
B
Visceral fat cells
C
Mucus cells
D
Oxyntic cells
View Answer & Propolis Autopsy
Correct Key: Option DDiagnostic Explanation
Concept:
The gastric gland is a pit-like structure with specific cell types occupying distinct anatomical zones within the gland.
Formula:
N/A
Solution:
In standard histological diagrams of the gastric gland, the larger, often bulged cells located prominently in the neck and upper body of the gland are the Parietal cells.
These cells are alternatively and properly referred to as Oxyntic cells, responsible for secreting Hydrochloric Acid (HCl).
Why other options are incorrect:
Mucus cells are strictly located at the very top (surface and upper neck). Visceral fat cells are not present within the epithelial lining. Mucosa is the name of the entire tissue layer, not a specific cell.
The small intestine is the primary site of nutrient absorption, but different segments have varying degrees of absorptive capacity.
Formula:
N/A
Solution:
The Jejunum is the middle section of the small intestine.
It is highly specialized with a massive surface area (villi and microvilli) and is the principal site where almost all types of nutrients (carbohydrates, proteins, lipids, vitamins) undergo their most active absorption into the bloodstream and lacteals.
Why other options are incorrect:
The duodenum is primarily focused on final chemical digestion. The ileum absorbs specific remnants like Vitamin B12 and bile salts. The colon absorbs mainly water and electrolytes.
The human vermiform appendix is a narrow, blind-ended tube connected to the gastrointestinal tract.
Formula:
N/A
Solution:
The large intestine begins with a pouch-like structure located in the lower right quadrant of the abdomen.
This starting pouch is called the Caecum.
The appendix extends directly downward from the inferior border of the caecum.
Why other options are incorrect:
The colon is the elongated portion that follows the caecum. The rectum is the terminal end of the large intestine. The small intestine connects to the caecum via the ileocecal valve, but does not give rise to the appendix.
Digestion of ____ starts in oral cavity due to the action of enzyme present in saliva.
A
Starch
B
Fatty Acids
C
Cellulose
D
Polypeptides
View Answer & Propolis Autopsy
Correct Key: Option ADiagnostic Explanation
Concept:
The chemical digestion of carbohydrates begins in the mouth, facilitated by the enzyme salivary amylase (ptyalin).
Formula:
N/A
Solution:
Salivary glands secrete saliva, which contains the enzyme salivary amylase.
This enzyme specifically targets the glycosidic bonds in complex carbohydrates like starch and glycogen, breaking them down into shorter polysaccharides and maltose.
Why other options are incorrect:
Fatty acids do not require digestion (they are already simple), cellulose is entirely indigestible by human enzymes, and polypeptide digestion begins in the stomach via pepsin, not the oral cavity.
The hormone which increases the secretion of pancreatic juice is:
A
Secretin
B
Thyroxine
C
Gastrin
D
Parathormone
View Answer & Propolis Autopsy
Correct Key: Option ADiagnostic Explanation
Concept:
When acidic chyme exits the stomach and enters the small intestine, the intestinal environment must be rapidly neutralized.
Formula:
N/A
Solution:
The acidic pH stimulates the S-cells of the duodenal mucosa to release the hormone Secretin.
Secretin travels via the blood to the pancreas, where it vigorously stimulates the secretion of pancreatic juice rich in bicarbonate ions (\(HCO_3^-\)).
This neutralizes the acid, providing the optimal alkaline pH for intestinal enzymes.
Why other options are incorrect:
Gastrin stimulates the stomach. Thyroxine regulates basal metabolic rate. Parathormone regulates blood calcium levels. None of these target the exocrine pancreas.
Pancreatic proteases are secreted in inactive zymogen forms to prevent the pancreas from digesting itself. They require a highly specific activator in the duodenum.
Formula:
N/A
Solution:
Trypsinogen is an inactive pancreatic enzyme.
Upon entering the duodenum, it encounters Enterokinase (also called enteropeptidase), an enzyme embedded in the brush border of the intestinal mucosa.
Enterokinase specifically cleaves a peptide segment from trypsinogen, transforming it into the active enzyme trypsin.
Why other options are incorrect:
HCl activates pepsinogen in the stomach, not trypsinogen. Mucus is protective. Gastrin is a stomach hormone.
Lipid digestion requires mechanical dispersion to increase surface area prior to enzymatic hydrolysis.
Formula:
N/A
Solution:
Bile is a yellowish-green fluid produced by the liver and stored in the gallbladder.
It contains no digestive enzymes itself, but is exceptionally rich in bile salts and phospholipids.
These components physically break down large lipid globules into an emulsion of tiny droplets, making them highly accessible to pancreatic lipases.
Why other options are incorrect:
Saliva initiates carbohydrate digestion. Gastrin is a hormone. Pancreatic juice provides the enzymes for chemical digestion, but relies on bile to do the physical emulsification first.
Gastric glands are composed of ____ types of cells.
A
Two
B
Four
C
Three
D
Five
View Answer & Propolis Autopsy
Correct Key: Option CDiagnostic Explanation
Concept:
Gastric glands are tubular structures in the stomach lining responsible for secreting gastric juice.
Formula:
N/A
Solution:
According to standard regional textbooks, the gastric gland consists of three major types of secretory cells:
1. Mucous cells (secrete protective mucus).
2. Parietal or Oxyntic cells (secrete HCl and intrinsic factor).
3. Chief or Zymogen cells (secrete pepsinogen).
Why other options are incorrect:
While advanced histology notes a fourth type (enteroendocrine/G-cells), standard biology curricula predominantly categorize them strictly into three principal exocrine cell types.
HCl in gastric juice is secreted by which one of the following cells?
A
Chief cells
B
Mucous cells
C
Oxyntic cells
D
Kupffer cells
View Answer & Propolis Autopsy
Correct Key: Option CDiagnostic Explanation
Concept:
The highly acidic environment of the stomach (pH ~2) is necessary to activate pepsinogen and denature dietary proteins.
Formula:
N/A
Solution:
Oxyntic cells, also universally known as parietal cells, are located in the stomach lining.
They actively pump hydrogen ions (\(H^+\)) and chloride ions (\(Cl^-\)) into the lumen, forming Hydrochloric Acid (HCl).
Why other options are incorrect:
Chief cells secrete pepsinogen. Mucous cells secrete mucus. Kupffer cells are specialized macrophages located in the liver, completely unrelated to gastric secretion.
In human, Escherichia coli is involved in the formation of:
A
Calcium
B
Vitamin A
C
Vitamin D
D
Vitamin K
View Answer & Propolis Autopsy
Correct Key: Option DDiagnostic Explanation
Concept:
The human large intestine hosts a massive microbiome of symbiotic bacteria that assist in physiological processes.
Formula:
N/A
Solution:
Escherichia coli (E. coli) and other commensal bacteria reside in the colon.
They ferment undigested carbohydrates and, importantly, synthesize certain essential vitamins that humans cannot produce on their own.
The most critical of these microbially synthesized compounds is Vitamin K, which is vital for blood coagulation processes.
Why other options are incorrect:
Calcium is a mineral absorbed from diet. Vitamin D is synthesized in the skin under UV light or obtained via diet. Vitamin A is derived from dietary carotenes. E. coli does not synthesize these.
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