Topic: Pancreatic Hormones; Subtopic: Insulin Biosynthesis
Keyword Definitions:
Insulin: Hormone produced by pancreatic β-cells that regulates blood glucose levels.
Pro-hormone: Inactive precursor of a hormone that requires processing to become active.
C-peptide: Connecting peptide linking A-chain and B-chain in proinsulin, removed during maturation.
A-peptide/B-peptide chain: Functional polypeptide chains of insulin after C-peptide removal.
β-cells: Pancreatic cells located in islets of Langerhans that synthesize insulin.
Proinsulin: Inactive form of insulin containing A-chain, B-chain, and C-peptide.
Mature insulin: Active hormone consisting of A-chain and B-chain linked by disulfide bonds.
Processing: Cleavage of C-peptide from proinsulin to generate biologically active insulin.
Lead Question – 2022 (Abroad)
Given below are two statements: one is labelled as Assertion (A) and the other as Reason (R).
Assertion (A): In human beings, insulin is synthesized as a pro-hormone which needs to be processed before it becomes fully mature and functional.
Reason (R): The extra stretch of C-peptide is to be removed from A-peptide and B-peptide chain of insulin.
In the light of the above statements, choose the most appropriate answer from the options below:
1. (A) is correct but (R) is not correct
2. (A) is not correct but (R) is correct
3. Both (A) and (R) are correct and (R) is the correct explanation of (A)
4. Both (A) and (R) are correct but (R) is not the correct explanation of (A)
Explanation:
Correct answer is option 3. Insulin is synthesized in pancreatic β-cells as an inactive precursor called proinsulin, consisting of the A-chain, B-chain, and C-peptide. During maturation, the C-peptide is enzymatically cleaved, leaving the A and B chains linked by disulfide bonds to form biologically active insulin. This processing ensures proper folding and functionality of insulin, while the C-peptide has no hormonal activity but is released in equimolar amounts. The reason accurately explains the assertion, as removal of C-peptide is essential for insulin to become fully mature and capable of regulating blood glucose levels effectively.
1. What is the role of C-peptide in insulin biosynthesis?
1. It is the active part of insulin
2. It stabilizes A and B chains during folding
3. It acts as a hormone itself
4. It remains attached in mature insulin
Explanation: Correct answer is It stabilizes A and B chains during folding. C-peptide is part of proinsulin and ensures proper folding of A and B chains via disulfide bond formation. It is cleaved during maturation to form active insulin. Though released in circulation, it has minimal direct hormonal activity, serving mainly as a marker for endogenous insulin production.
2. Proinsulin consists of:
1. Only A and B chains
2. A-chain, B-chain, and C-peptide
3. C-peptide only
4. Single polypeptide chain without cleavage sites
Explanation: Correct answer is A-chain, B-chain, and C-peptide. Proinsulin is a single-chain precursor containing A-chain, B-chain, and the connecting C-peptide. The C-peptide is cleaved enzymatically to generate mature insulin consisting of two chains linked by disulfide bonds. This precursor ensures correct folding and proper structural formation of active insulin in β-cells.
3. Which cells synthesize insulin in humans?
1. α-cells of pancreas
2. β-cells of pancreas
3. δ-cells of pancreas
4. Exocrine acinar cells
Explanation: Correct answer is β-cells of pancreas. β-cells in the islets of Langerhans produce proinsulin, which is processed into active insulin. α-cells secrete glucagon, δ-cells secrete somatostatin, and acinar cells are exocrine, producing digestive enzymes. β-cells are central to glucose homeostasis through regulated insulin secretion.
4. Mature insulin consists of:
1. Only A-chain
2. Only B-chain
3. A-chain and B-chain linked by disulfide bonds
4. A-chain, B-chain, and C-peptide
Explanation: Correct answer is A-chain and B-chain linked by disulfide bonds. Upon cleavage of C-peptide from proinsulin, the A and B chains are joined by disulfide bridges to form active insulin. This structure is critical for receptor binding and glucose regulation. C-peptide is removed but secreted separately in equimolar amounts.
5. Removal of C-peptide from proinsulin is necessary because:
1. C-peptide is toxic
2. Only A and B chains are biologically active
3. It prevents folding of insulin
4. It reduces insulin solubility
Explanation: Correct answer is Only A and B chains are biologically active. C-peptide serves as a connector during folding but has no direct hormonal effect. Its removal produces mature insulin capable of binding to insulin receptors. Proper cleavage ensures functional hormone secretion and regulation of blood glucose.
6. The term “pro-hormone” refers to:
1. Active hormone
2. Inactive precursor requiring processing
3. Hormone degraded in liver
4. Hormone bound to carrier protein
Explanation: Correct answer is Inactive precursor requiring processing. Proinsulin is a pro-hormone, inactive until enzymatic removal of C-peptide. Pro-hormones ensure correct folding, storage, and regulated activation of hormones. This mechanism prevents premature activity and maintains homeostasis.
7. Assertion-Reason:
Assertion (A): Insulin is synthesized as a pro-hormone.
Reason (R): Proinsulin contains C-peptide which must be removed to activate insulin.
1. Both A and R are true, R is correct explanation of A
2. Both A and R are true, R is not correct explanation
3. A is true, R is false
4. A is false, R is true
Explanation: Correct answer is option 1. Insulin is synthesized as proinsulin in β-cells. The C-peptide connects the A and B chains and is removed enzymatically to produce mature, biologically active insulin. The reason accurately explains the assertion, linking pro-hormone processing to activation of insulin.
8. Matching Type:
Match List-I (Molecule) with List-II (Function):
A. Proinsulin – (i) Inactive precursor
B. C-peptide – (ii) Connector peptide during folding
C. Mature insulin – (iii) Regulates blood glucose
D. β-cells – (iv) Site of synthesis
1. A–i, B–ii, C–iii, D–iv
2. A–ii, B–i, C–iv, D–iii
3. A–iii, B–ii, C–i, D–iv
4. A–iv, B–iii, C–ii, D–i
Explanation: Correct answer is option 1. Proinsulin is the inactive precursor (A–i), C-peptide stabilizes A and B chains (B–ii), mature insulin regulates blood glucose (C–iii), and β-cells are the synthesis site (D–iv). This illustrates biosynthesis, processing, and functional role of insulin and associated peptides.
9. Fill in the Blanks:
The __________ is cleaved from proinsulin to produce active insulin.
1. A-chain
2. B-chain
3. C-peptide
4. β-cell nucleus
Explanation: Correct answer is C-peptide. During insulin maturation, the connecting C-peptide is enzymatically removed, leaving A and B chains linked by disulfide bonds. This cleavage converts proinsulin to biologically active insulin, enabling glucose regulation. The C-peptide is secreted in equimolar amounts but has no direct hormonal function.
10. Choose the Correct Statements:
Statement I: Proinsulin contains A-chain, B-chain, and C-peptide.
Statement II: Mature insulin contains all three components including C-peptide.
1. Statement I correct, Statement II incorrect
2. Statement I incorrect, Statement II correct
3. Both statements correct
4. Both statements incorrect
Explanation: Correct answer is Statement I correct, Statement II incorrect. Proinsulin has A, B chains, and C-peptide, while mature insulin only contains A and B chains linked by disulfide bonds. Removal of C-peptide is essential for activation. This illustrates the processing step critical in hormone maturation and function.
Topic: Hormones of Digestive System; Subtopic: Intestinal Hormones
Keyword Definitions:
Enterokinin: An intestinal hormone secreted by the small intestine that stimulates pancreatic secretion rich in bicarbonate ions.
Pancreas: A glandular organ that secretes digestive enzymes and bicarbonate-rich fluid to neutralize stomach acid.
Bicarbonate ions (HCO₃⁻): Ions that neutralize acidic chyme entering the small intestine from the stomach.
Cholecystokinin (CCK): A hormone that stimulates gall bladder contraction and pancreatic enzyme secretion.
Lead Question – 2022 (Abroad)
An intestinal hormone that stimulates the pancreas to release a watery secretion that is rich in bicarbonate ions:
1. Cholecystokinin
2. Gastric Inhibitory Peptide
3. Enterokinin
4. Secretion
Explanation:
The correct answer is Enterokinin. This hormone, secreted by the mucosa of the small intestine, stimulates the pancreas to release a watery fluid rich in bicarbonate ions, which neutralizes acidic chyme entering from the stomach. It is essential for maintaining optimal pH in the duodenum for enzyme activity and digestion efficiency.
1. Which hormone stimulates pancreatic enzyme secretion?
1. Secretin
2. Enterokinin
3. Gastrin
4. Insulin
Explanation: Enterokinin stimulates the pancreas to secrete bicarbonate-rich watery fluid, while other hormones like gastrin primarily regulate stomach acid and secretin mainly stimulates bicarbonate secretion from the pancreas. Its activity ensures neutralization of chyme for proper enzymatic digestion in the small intestine.
2. Which ion is abundant in pancreatic secretion stimulated by enterokinin?
1. Chloride
2. Bicarbonate (HCO₃⁻)
3. Sodium
4. Potassium
Explanation: Enterokinin-stimulated pancreatic secretion is rich in bicarbonate ions (HCO₃⁻). These ions neutralize acidic chyme from the stomach, providing an optimal pH for pancreatic enzymes like amylase, lipase, and proteases, which function best in slightly alkaline conditions, ensuring efficient digestion and nutrient absorption.
3. Enterokinin is secreted by which part of the digestive system?
1. Stomach
2. Small intestine
3. Large intestine
4. Pancreas
Explanation: Enterokinin is secreted by the epithelial cells of the small intestine, mainly in the duodenum and jejunum. Its secretion is triggered by the presence of chyme, and it signals the pancreas to release a bicarbonate-rich secretion, neutralizing acidity and creating suitable conditions for enzymatic digestion.
4. Which hormone triggers gall bladder contraction along with pancreatic enzyme release?
1. Enterokinin
2. Secretin
3. Cholecystokinin (CCK)
4. Gastric Inhibitory Peptide
Explanation: Cholecystokinin (CCK) stimulates gall bladder contraction and release of bile, along with pancreatic enzyme secretion. It complements enterokinin, which primarily stimulates bicarbonate-rich fluid from the pancreas, aiding in fat digestion and overall digestive efficiency in the duodenum.
5. Bicarbonate-rich pancreatic secretion helps in:
1. Protein breakdown in the stomach
2. Neutralizing acidic chyme
3. Stimulating gastric acid
4. Absorbing water in colon
Explanation: The bicarbonate-rich secretion stimulated by enterokinin neutralizes acidic chyme entering the small intestine from the stomach. This neutralization prevents mucosal damage, provides optimal pH for pancreatic enzyme activity, and ensures efficient digestion of carbohydrates, proteins, and fats.
6. Which of the following is not secreted by the small intestine?
1. Enterokinin
2. Secretin
3. Gastrin
4. Cholecystokinin (CCK)
Explanation: Gastrin is primarily secreted by the stomach to stimulate acid production. Other hormones like enterokinin, secretin, and CCK are secreted by the small intestine to regulate pancreatic secretion, bile release, and neutralization of chyme, ensuring effective digestion and absorption.
7. Assertion-Reason Type:
Assertion (A): Enterokinin stimulates bicarbonate secretion from the pancreas.
Reason (R): Neutralization of acidic chyme is required for optimal enzymatic digestion.
1. Both A and R are true, and R is the correct explanation of A.
2. Both A and R are true, but R is not the correct explanation of A.
3. A is true, but R is false.
4. A is false, but R is true.
Explanation: The correct answer is option 1. Enterokinin stimulates the pancreas to release bicarbonate-rich fluid. This action neutralizes acidic chyme from the stomach, creating an alkaline environment necessary for digestive enzymes to function efficiently in the duodenum.
8. Matching Type:
Match the hormone with its function:
A. Enterokinin – (i) Stimulates pancreatic bicarbonate secretion
B. Secretin – (ii) Stimulates water and bicarbonate secretion
C. Cholecystokinin – (iii) Stimulates bile release
D. Gastrin – (iv) Stimulates gastric acid secretion
1. A–i, B–ii, C–iii, D–iv
2. A–ii, B–i, C–iv, D–iii
3. A–iii, B–i, C–ii, D–iv
4. A–iv, B–ii, C–i, D–iii
Explanation: The correct answer is option 1. Enterokinin stimulates pancreatic bicarbonate secretion, secretin promotes watery alkaline fluid, CCK stimulates bile and pancreatic enzyme release, and gastrin increases gastric acid secretion, coordinating digestion in the gastrointestinal tract efficiently.
9. Fill in the Blanks:
_________ is secreted by the small intestine to neutralize acidic chyme.
1. Cholecystokinin
2. Enterokinin
3. Secretin
4. Gastrin
Explanation: The blank is filled with Enterokinin. It stimulates the pancreas to release a watery, bicarbonate-rich secretion, which neutralizes the acidic chyme entering from the stomach, providing an optimal pH for enzymatic activity in the duodenum and facilitating efficient nutrient digestion.
10. Choose the Correct Statements:
Statement I: Enterokinin stimulates the pancreas to secrete bicarbonate-rich fluid.
Statement II: Bicarbonate neutralizes chyme, aiding in digestion.
1. Both statements are correct
2. Both statements are incorrect
3. Statement I is correct, Statement II is incorrect
4. Statement I is incorrect, Statement II is correct
Explanation: The correct answer is option 1. Enterokinin stimulates the pancreas to secrete a bicarbonate-rich fluid. This fluid neutralizes acidic chyme from the stomach, maintaining an optimal pH for enzyme activity and efficient digestion, ensuring proper nutrient breakdown and absorption in the small intestine.
Subtopic: Absorption of Lipids
Keyword Definitions:
Chylomicrons: Protein-coated fat droplets that transport absorbed lipids from the intestine to other tissues.
Lipid Absorption: Process of uptake of fatty acids and monoglycerides into intestinal cells for conversion into triglycerides.
Lacteals: Lymphatic capillaries within intestinal villi that transport chylomicrons.
Micelles: Small spherical lipid aggregates that help in fat absorption by ferrying lipids to intestinal walls.
Emulsification: Breakdown of large fat globules into smaller ones by bile salts to aid digestion.
Lead Question - 2022 (Abroad)
Chylomicrons are:
1. fat coated protein globules
2. micro-sized lipid molecules
3. protein coated fat globules
4. spherical aggregates of fatty acids
Explanation: Chylomicrons are protein-coated fat globules that form inside the intestinal epithelial cells after absorption of lipids. These structures carry triglycerides, cholesterol, and phospholipids through the lymphatic system into the bloodstream. They play a crucial role in lipid transport from the intestine to tissues. Hence, option 3 is correct.
1. During fat digestion, bile salts help in formation of ______ which aid in lipid absorption.
1. micelles
2. chylomicrons
3. triglycerides
4. phospholipids
Explanation: Bile salts emulsify fats and help form micelles — tiny lipid droplets that increase surface area for lipase action and assist absorption into intestinal cells. Micelles then deliver fatty acids and monoglycerides to epithelial cells for triglyceride synthesis. Thus, micelles are essential for lipid absorption. Option 1 is correct.
2. The lymphatic vessel responsible for transport of chylomicrons from the intestine is:
1. Hepatic portal vein
2. Lacteal
3. Thoracic duct
4. Mesenteric vein
Explanation: Chylomicrons enter the lymphatic system through lacteals located in the intestinal villi. From there, they travel via the thoracic duct into the bloodstream. This pathway prevents immediate hepatic metabolism and allows gradual fat distribution. Thus, lacteals are the transport structures. Option 2 is correct.
3. The main enzyme involved in the breakdown of dietary fats into fatty acids and glycerol is:
1. Pepsin
2. Lipase
3. Amylase
4. Maltase
Explanation: Lipase, secreted by the pancreas, is the main enzyme responsible for the hydrolysis of triglycerides into fatty acids and monoglycerides. These products combine with bile salts to form micelles for absorption. Other enzymes digest proteins and carbohydrates. Hence, lipase is correct. Option 2 is correct.
4. Which of the following statements about micelles is correct?
1. They are protein-coated fat globules.
2. They transport lipids from intestine to tissues.
3. They help in absorption of fatty acids into epithelial cells.
4. They are stored in the liver.
Explanation: Micelles are small lipid aggregates formed with bile salts that transport digested lipids to the intestinal epithelial cells for absorption. They are not protein-coated and do not circulate in the blood. Their role ends at absorption. Thus, option 3 is correct.
5. The end product of fat digestion in the small intestine is:
1. Fatty acids and monoglycerides
2. Polysaccharides
3. Amino acids
4. Disaccharides
Explanation: Dietary triglycerides are digested by pancreatic lipase into free fatty acids and monoglycerides. These then form micelles for absorption into intestinal cells. Carbohydrates yield sugars, and proteins yield amino acids. Thus, fatty acids and monoglycerides are the correct products. Option 1 is correct.
6. After absorption, lipids are first transported via:
1. Hepatic portal vein
2. Lymphatic system
3. Renal vein
4. Inferior vena cava
Explanation: Lipids absorbed as chylomicrons enter lacteals and move through the lymphatic system before reaching the bloodstream via the thoracic duct. This bypasses initial liver metabolism, unlike carbohydrates and proteins. Hence, lipids first move through the lymphatic system. Option 2 is correct.
7. Assertion-Reason Question:
Assertion (A): Chylomicrons are released into lacteals rather than blood capillaries.
Reason (R): Chylomicrons are too large to pass through blood capillary pores.
1. Both A and R are true, and R is the correct explanation of A.
2. Both A and R are true, but R is not the correct explanation of A.
3. A is true but R is false.
4. A is false but R is true.
Explanation: Chylomicrons are large lipid-protein complexes that cannot enter the narrow pores of blood capillaries. Therefore, they are released into lacteals, which have larger openings. Hence both statements are true, and R correctly explains A. Option 1 is correct.
8. Matching Type Question:
Match the following components with their functions:
A. Bile salts — (i) Breakdown of proteins
B. Lipase — (ii) Emulsification of fats
C. Pepsin — (iii) Hydrolysis of fats
D. Chylomicrons — (iv) Transport of lipids
1. A-(ii), B-(iii), C-(i), D-(iv)
2. A-(iv), B-(ii), C-(iii), D-(i)
3. A-(i), B-(iii), C-(ii), D-(iv)
4. A-(iii), B-(iv), C-(ii), D-(i)
Explanation: Bile salts emulsify fats; lipase hydrolyzes fats; pepsin digests proteins; chylomicrons transport lipids. Thus, the correct match is A-(ii), B-(iii), C-(i), D-(iv). Option 1 is correct.
9. Fill in the Blanks / Completion Question:
The absorbed fatty acids and monoglycerides are resynthesized into triglycerides within intestinal cells and coated with proteins to form ______.
1. Micelles
2. Chylomicrons
3. Liposomes
4. Glycoproteins
Explanation: Inside intestinal epithelial cells, absorbed fatty acids and monoglycerides are recombined into triglycerides and coated with proteins to form chylomicrons, which enter lacteals. This enables fat transport in aqueous environments. Thus, the blank is filled by “chylomicrons.” Option 2 is correct.
10. Choose the Correct Statements (Statement I & Statement II):
Statement I: Lipids are directly absorbed into the blood capillaries of villi.
Statement II: Lipids are absorbed into lacteals as chylomicrons.
1. Both statements are true.
2. Both statements are false.
3. Statement I is true and Statement II is false.
4. Statement I is false and Statement II is true.
Explanation: Lipids are absorbed into intestinal cells, converted into chylomicrons, and transported via lacteals, not blood capillaries. Hence, Statement I is false and Statement II is true. Therefore, option 4 is correct.
Topic: Digestive Enzymes
Subtopic: Functions of Salivary Glands
Keyword Definitions:
Salivary Glands: Exocrine glands in the mouth that secrete saliva for lubrication and digestion.
Saliva: A watery secretion containing enzymes like salivary amylase, mucins, and lysozymes.
Amylase: Enzyme that breaks down starch into maltose.
Lysozyme: Antibacterial enzyme that helps control bacterial growth in the mouth.
Lead Question (2022):
Which of the following functions is not performed by secretions from salivary glands:
(1) Digestion of complex carbohydrates
(2) Lubrication of oral cavity
(3) Digestion of disaccharides
(4) Control bacterial population in mouth
Explanation: Saliva contains salivary amylase that digests starch into maltose and mucin for lubrication. It also contains lysozyme, which controls bacterial growth. However, digestion of disaccharides occurs in the small intestine, not by salivary secretion. Hence, the correct answer is option (3).
1. Which enzyme in saliva helps in the breakdown of starch?
(1) Maltase
(2) Sucrase
(3) Salivary amylase
(4) Lactase
Explanation: Salivary amylase (ptyalin) is secreted by salivary glands and acts on starch to form maltose. It functions optimally at a slightly acidic to neutral pH. The other enzymes act later in the intestine. Hence, the correct answer is option (3).
2. Saliva does not contain:
(1) Lysozyme
(2) Mucin
(3) Amylase
(4) Pepsin
Explanation: Pepsin is a proteolytic enzyme secreted in the stomach, not in saliva. Saliva contains amylase, lysozyme, and mucin. Pepsin works at a very low pH, unlike saliva which is slightly acidic. Hence, the correct answer is option (4).
3. Which of the following is a function of lysozyme in saliva?
(1) Digestion of starch
(2) Killing bacteria
(3) Lubrication
(4) Breakdown of fats
Explanation: Lysozyme is an enzyme in saliva with antibacterial properties. It breaks down bacterial cell walls and prevents oral infections, maintaining hygiene in the mouth. It does not participate in digestion. Hence, the correct answer is option (2).
4. Which salivary gland produces maximum saliva during eating?
(1) Sublingual
(2) Parotid
(3) Submandibular
(4) Buccal
Explanation: Parotid glands are the largest salivary glands and produce most of the watery secretion containing amylase during eating. Submandibular and sublingual glands contribute mucus-rich saliva. Hence, the correct answer is option (2).
5. Which of the following statements is true regarding saliva?
(1) It is slightly acidic in nature
(2) It contains trypsin
(3) It aids in starch digestion
(4) It helps in fat digestion
Explanation: Saliva is slightly acidic to neutral and helps in starch digestion through salivary amylase. Trypsin acts in the small intestine, not in the mouth. Hence, the correct answer is option (3).
6. Digestion of starch begins in which part of the alimentary canal?
(1) Stomach
(2) Mouth
(3) Duodenum
(4) Ileum
Explanation: Digestion of starch begins in the mouth due to the action of salivary amylase secreted by the salivary glands. It converts starch into maltose. Hence, the correct answer is option (2).
7. Assertion (A): Saliva contains lysozyme which kills bacteria.
Reason (R): Lysozyme is a carbohydrate digesting enzyme.
(1) Both A and R are true, and R is the correct explanation of A
(2) Both A and R are true, but R is not the correct explanation of A
(3) A is true, but R is false
(4) A is false, but R is true
Explanation: Lysozyme in saliva kills bacteria by lysing their cell walls. It is not a carbohydrate-digesting enzyme. Thus, A is true, but R is false. Hence, the correct answer is option (3).
8. Matching Type: Match the following enzymes with their functions:
A. Salivary amylase
B. Pepsin
C. Lipase
D. Trypsin
(1) A–Starch → Maltose, B–Protein → Peptides, C–Fats → Fatty acids, D–Peptides → Amino acids
(2) A–Fats → Fatty acids, B–Protein → Peptides, C–Starch → Maltose, D–Peptides → Amino acids
(3) A–Peptides → Amino acids, B–Fats → Fatty acids, C–Starch → Maltose, D–Protein → Peptides
(4) A–Protein → Peptides, B–Fats → Fatty acids, C–Peptides → Amino acids, D–Starch → Maltose
Explanation: Salivary amylase digests starch to maltose, pepsin breaks proteins into peptides, lipase converts fats into fatty acids and glycerol, and trypsin continues peptide digestion. Hence, the correct answer is option (1).
9. Fill in the blanks:
Salivary glands secrete ___________ which starts the digestion of starch.
(1) Lipase
(2) Amylase
(3) Maltase
(4) Trypsin
Explanation: Amylase (ptyalin) secreted by salivary glands initiates starch digestion in the mouth, forming maltose. Hence, the correct answer is option (2).
10. Choose the correct statements:
(a) Saliva aids in starch digestion.
(b) Lysozyme in saliva kills bacteria.
(c) Pepsin is present in saliva.
(d) Mucin helps in lubrication.
(1) a, b, and d only
(2) a and c only
(3) b and c only
(4) a, b, c, and d
Explanation: Saliva digests starch using amylase, controls bacteria using lysozyme, and lubricates food through mucin. Pepsin is not present in saliva. Hence, the correct answer is option (1).
Topic: Absorption of Digested Products
Subtopic: Absorption of Lipids
Keyword Definitions:
Fatty acids: Simple lipids formed from fats during digestion.
Glycerol: A three-carbon compound that combines with fatty acids to form fats.
Lacteals: Specialized lymphatic vessels in intestinal villi that absorb fats.
Chylomicrons: Microscopic fat droplets formed in intestinal cells, carried by lymph.
Absorption: Process by which digested nutrients pass into the bloodstream or lymph.
Lead Question – 2022
Given below are two statements:
Statement I: Fatty acids and glycerols cannot be absorbed in the blood.
Statement II: Specialized lymphatic capillaries called lacteals carry chylomicrons into lymphatic vessels and ultimately into the blood.
In the light of the above statements, choose the most appropriate answer:
(1) Both Statement I and Statement II are incorrect
(2) Statement I is correct but Statement II is incorrect
(3) Statement I is incorrect but Statement II is correct
(4) Both Statement I and Statement II are correct
Explanation: Fatty acids and glycerol are not directly absorbed into blood but into lymph via lacteals as chylomicrons, which later enter the bloodstream. Hence, Statement I is incorrect while Statement II is correct. The correct answer is (3) Statement I is incorrect but Statement II is correct.
1. The absorption of amino acids occurs mainly in:
(1) Stomach
(2) Small intestine
(3) Large intestine
(4) Liver
Explanation: Amino acids, being water-soluble end products of protein digestion, are absorbed in the small intestine through active and facilitated transport into blood capillaries. The correct answer is (2) Small intestine.
2. The end products of fat digestion are:
(1) Monosaccharides
(2) Amino acids
(3) Fatty acids and glycerol
(4) Peptides
Explanation: Fats are hydrolyzed by lipase into fatty acids and glycerol, which are absorbed in the small intestine. The correct answer is (3) Fatty acids and glycerol.
3. Bile salts aid in the digestion of fats by:
(1) Breaking peptide bonds
(2) Emulsifying fats
(3) Activating pepsin
(4) Increasing gastric juice
Explanation: Bile salts emulsify large fat globules into smaller ones, increasing the surface area for enzyme action. The correct answer is (2) Emulsifying fats.
4. Chylomicrons are formed in:
(1) Liver cells
(2) Intestinal epithelial cells
(3) Pancreatic cells
(4) Adipose tissue
Explanation: Chylomicrons are small lipid-protein complexes formed in intestinal epithelial cells to transport fats through lymphatic vessels. The correct answer is (2) Intestinal epithelial cells.
5. Which part of the alimentary canal absorbs the maximum water?
(1) Stomach
(2) Small intestine
(3) Large intestine
(4) Rectum
Explanation: The large intestine absorbs most of the remaining water and electrolytes from undigested food. The correct answer is (3) Large intestine.
6. The brush border is associated with:
(1) Stomach
(2) Small intestine
(3) Esophagus
(4) Pancreas
Explanation: The brush border, formed by microvilli, is present on the epithelial cells of the small intestine, aiding in nutrient absorption. The correct answer is (2) Small intestine.
7. Assertion (A): Bile helps in the digestion of lipids.
Reason (R): Bile contains lipase enzyme for lipid digestion.
(1) Both A and R are true and R is the correct explanation
(2) Both A and R are true but R is not the correct explanation
(3) A is true but R is false
(4) A is false but R is true
Explanation: Bile does not contain any enzyme; it emulsifies fats to aid enzyme action. Hence, A is true but R is false. The correct answer is (3).
8. Match the following:
A. Lipase — (i) Fats
B. Amylase — (ii) Starch
C. Pepsin — (iii) Proteins
Options:
(1) A-(ii), B-(i), C-(iii)
(2) A-(i), B-(ii), C-(iii)
(3) A-(iii), B-(i), C-(ii)
(4) A-(i), B-(iii), C-(ii)
Explanation: Lipase acts on fats, amylase on starch, and pepsin on proteins. The correct answer is (2) A-(i), B-(ii), C-(iii).
9. Fill in the blank:
The digestion of starch begins in the ______.
(1) Stomach
(2) Small intestine
(3) Mouth
(4) Large intestine
Explanation: Salivary amylase in saliva begins starch digestion in the mouth, converting it to maltose. The correct answer is (3) Mouth.
10. Choose the correct statements:
(1) Bile is secreted by pancreas
(2) Emulsification of fats occurs in the small intestine
(3) Absorption of amino acids occurs in the large intestine
(4) Lipase acts in the stomach
Explanation: Bile secreted by the liver emulsifies fats in the small intestine for easier digestion by lipase. The correct answer is (2) Emulsification of fats occurs in the small intestine.
Sphincter of Oddi: Muscular valve controlling the flow of bile and pancreatic juice into the duodenum.
Hepato-pancreatic duct: Duct formed by union of common bile duct and pancreatic duct.
Duodenum: First part of small intestine, site of enzymatic digestion.
Gastro-oesophageal junction: Junction of esophagus and stomach, prevents reflux.
Jejunum: Middle portion of small intestine, mainly for absorption.
Ileo-caecal junction: Junction between ileum and cecum, controls passage of contents into large intestine.
Bile: Digestive fluid produced by liver, stored in gallbladder, aids in fat emulsification.
Pancreatic juice: Contains digestive enzymes secreted by pancreas.
Valve: Structure controlling the direction and flow of fluids.
Digestion: Breakdown of food into absorbable forms.
Exocrine secretion: Release of digestive enzymes via ducts.
Lead Question - 2021
Sphincter of Oddi is present at:
(1) Junction of hepato-pancreatic duct and duodenum
(2) Gastro-oesophageal junction
(3) Junction of jejunum and duodenum
(4) Ileo-caecal junction
Explanation: The Sphincter of Oddi is a muscular valve at the junction of the hepato-pancreatic duct and duodenum. It regulates the flow of bile and pancreatic juice into the duodenum and prevents reflux of intestinal contents. Answer: Junction of hepato-pancreatic duct and duodenum.
1. Single Correct Answer MCQ: The primary function of Sphincter of Oddi is:
Options:
A. Control flow of bile and pancreatic juice
B. Prevent reflux of gastric acid
C. Absorb nutrients
D. Connect ileum to cecum
Explanation: The Sphincter of Oddi controls the release of bile and pancreatic juice into the duodenum and prevents reflux. Answer: Control flow of bile and pancreatic juice.
2. Single Correct Answer MCQ: Which of the following ducts join to form the hepato-pancreatic duct?
Options:
A. Pancreatic duct and cystic duct
B. Common bile duct and pancreatic duct
C. Hepatic duct and jejunal duct
D. Cystic duct and ileal duct
Explanation: The common bile duct carrying bile and pancreatic duct carrying pancreatic enzymes unite to form the hepato-pancreatic duct, which opens into duodenum through Sphincter of Oddi. Answer: Common bile duct and pancreatic duct.
3. Single Correct Answer MCQ: Which part of the small intestine receives bile and pancreatic juice?
Options:
A. Jejunum
B. Ileum
C. Duodenum
D. Cecum
Explanation: The duodenum is the first segment of the small intestine and receives bile and pancreatic juice via the Sphincter of Oddi for digestion. Answer: Duodenum.
4. Single Correct Answer MCQ: Which hormone stimulates Sphincter of Oddi to relax?
Options:
A. Secretin
B. Gastrin
C. Cholecystokinin (CCK)
D. Insulin
Explanation: CCK released by duodenal mucosa during digestion of fats causes relaxation of Sphincter of Oddi and contraction of gallbladder, promoting bile flow into duodenum. Answer: Cholecystokinin (CCK).
5. Single Correct Answer MCQ: Obstruction of Sphincter of Oddi can cause:
Options:
A. Jaundice
B. Gastric ulcer
C. Diarrhea
D. Constipation
Explanation: Blockage of Sphincter of Oddi leads to accumulation of bile in liver and pancreatic ducts, resulting in jaundice due to elevated bilirubin. Answer: Jaundice.
6. Single Correct Answer MCQ: Sphincter of Oddi is classified as:
Options:
A. Skeletal muscle valve
B. Smooth muscle sphincter
C. Cartilaginous ring
D. Fibrous ligament
Explanation: The Sphincter of Oddi is composed of smooth muscle fibers, forming a sphincter to regulate bile and pancreatic juice flow. Answer: Smooth muscle sphincter.
7. Assertion-Reason MCQ:
Assertion (A): Sphincter of Oddi regulates bile flow.
Reason (R): It is present at the junction of ileum and cecum.
Options:
A. Both A and R true, R correct explanation
B. Both A and R true, R not correct explanation
C. A true, R false
D. A false, R true
Explanation: The Sphincter of Oddi controls bile and pancreatic juice flow into duodenum. Reason about ileo-cecal junction is false. Answer: A true, R false.
8. Matching Type MCQ:
List I: 1. Valve controlling bile 2. First part of small intestine 3. Hormone relaxing sphincter 4. Obstruction effect
List II: A. Duodenum B. Jaundice C. CCK D. Sphincter of Oddi
Options:
A. 1-D, 2-A, 3-C, 4-B
B. 1-A, 2-D, 3-B, 4-C
C. 1-D, 2-B, 3-A, 4-C
D. 1-C, 2-A, 3-D, 4-B
Explanation: Valve controlling bile is Sphincter of Oddi, duodenum is first small intestine part, CCK relaxes sphincter, obstruction causes jaundice. Answer: 1-D, 2-A, 3-C, 4-B.
9. Fill in the Blank MCQ: The Sphincter of Oddi opens into the ______.
Options:
A. Stomach
B. Duodenum
C. Jejunum
D. Ileum
Succus entericus: The clear intestinal juice secreted by glands of the small intestine containing enzymes for digestion.
Intestinal juice: Another term for succus entericus, aids in the final digestion of nutrients.
Gastric juice: Acidic secretion of the stomach containing pepsin and hydrochloric acid for protein digestion.
Chyme: Semiliquid mass of partially digested food from the stomach to small intestine.
Pancreatic juice: Secretion from pancreas containing digestive enzymes and bicarbonate ions for neutralizing stomach acid.
Small intestine: Major site of digestion and absorption in humans.
Enzymes: Proteins that catalyze chemical reactions, such as amylase, lipase, and proteases.
Absorption: Process of nutrients entering blood or lymph from the digestive tract.
Brush border enzymes: Enzymes located on the microvilli of small intestine, aiding final digestion.
Duodenum: First segment of small intestine where succus entericus is secreted.
Secretions: Fluids released by glands to aid digestion and absorption.
Lead Question - 2021
Succus entericus is referred to as :
(1) Intestinal juice
(2) Gastric juice
(3) Chyme
(4) Pancreatic juice
Explanation: Succus entericus is the intestinal juice secreted by the small intestine glands, containing enzymes such as maltase, lactase, and peptidases that complete digestion. It facilitates absorption of nutrients. Other options like gastric juice, chyme, and pancreatic juice are different digestive secretions. Answer: Intestinal juice.
1. Single Correct Answer MCQ: Which organ secretes succus entericus?
Options:
A. Stomach
B. Small intestine
C. Pancreas
D. Liver
Explanation: Small intestine secretes succus entericus, containing enzymes for final digestion of carbohydrates, proteins, and fats. Stomach secretes gastric juice, pancreas secretes pancreatic juice, and liver secretes bile. Answer: Small intestine.
2. Single Correct Answer MCQ: Succus entericus contains enzymes for digesting:
Options:
A. Carbohydrates only
B. Proteins only
C. Lipids only
D. Carbohydrates, proteins, and lipids
Explanation: Succus entericus contains maltase, lactase, sucrase for carbohydrates, peptidases for proteins, and lipase for fats, completing the digestion process in the small intestine. Answer: Carbohydrates, proteins, and lipids.
3. Single Correct Answer MCQ: Succus entericus is secreted by:
Options:
A. Gastric glands
B. Intestinal glands
C. Pancreatic acini
D. Liver cells
Explanation: Intestinal glands or crypts of Lieberkühn secrete succus entericus, providing enzymes and watery medium for digestion and absorption. Gastric glands secrete gastric juice, pancreatic acini secrete pancreatic juice. Answer: Intestinal glands.
4. Single Correct Answer MCQ: Main function of succus entericus is:
Options:
A. Acidifying chyme
B. Completing digestion
C. Storing bile
D. Neutralizing stomach acid
Explanation: Succus entericus contains enzymes that complete the digestion of carbohydrates, proteins, and fats in the small intestine, preparing nutrients for absorption. It does not acidify chyme, store bile, or neutralize stomach acid. Answer: Completing digestion.
5. Single Correct Answer MCQ: Which enzyme is present in succus entericus?
Options:
A. Pepsin
B. Maltase
C. Trypsin
D. Amylase (salivary)
Explanation: Maltase is present in succus entericus and hydrolyzes maltose into glucose. Pepsin is in gastric juice, trypsin in pancreatic juice, and salivary amylase in saliva. Answer: Maltase.
6. Single Correct Answer MCQ: Succus entericus is secreted primarily in:
Options:
A. Duodenum
B. Stomach
C. Jejunum
D. Ileum
Explanation: Duodenum receives chyme from the stomach and is the primary site where succus entericus is secreted, mixing digestive enzymes for nutrient absorption. Answer: Duodenum.
7. Assertion-Reason MCQ:
Assertion (A): Succus entericus facilitates nutrient absorption.
Reason (R): It contains digestive enzymes for carbohydrates, proteins, and fats.
Options:
A. Both A and R true, R correct explanation
B. Both A and R true, R not correct explanation
C. A true, R false
D. A false, R true
Explanation: Succus entericus completes digestion using enzymes for carbohydrates, proteins, and fats, which directly facilitates nutrient absorption in the small intestine. Both assertion and reason are correct and reason explains the assertion. Answer: Both A and R true, R correct explanation.
8. Matching Type MCQ:
Column I: 1. Maltase 2. Lactase 3. Peptidase 4. Lipase
Column II: A. Succus entericus B. Gastric juice C. Pancreatic juice D. Saliva
Options:
A. 1-A, 2-A, 3-A, 4-A
B. 1-B, 2-D, 3-C, 4-A
C. 1-A, 2-C, 3-B, 4-D
D. 1-D, 2-B, 3-C, 4-A
Explanation: All enzymes maltase, lactase, peptidase, and lipase are secreted in succus entericus to complete digestion in the small intestine. Answer: 1-A, 2-A, 3-A, 4-A.
9. Fill in the Blank MCQ: The intestinal juice secreted by crypts of Lieberkühn is called ______.
Options:
A. Gastric juice
B. Succus entericus
C. Pancreatic juice
D. Chyme
Explanation: Succus entericus is the intestinal juice secreted by crypts of Lieberkühn in the small intestine, aiding digestion and absorption. Other options are different digestive fluids. Answer: Succus entericus.
10. Choose the correct statements MCQ:
(a) Succus entericus contains enzymes for digestion.
(b) It is secreted by stomach glands.
(c) It helps in nutrient absorption.
(d) It is acidic in nature.
Options:
1. (a) and (c) only
2. (b) and (d) only
3
Subtopic: Enzymes of Digestion
Keyword Definitions:
Rennin: Proteolytic enzyme that coagulates milk, secreted by gastric chief cells in infants.
Gastric juice: Digestive fluid secreted by stomach containing pepsin, rennin, hydrochloric acid.
Intestinal juice: Also called succus entericus, contains enzymes like maltase and peptidases.
Bile juice: Secreted by liver, stored in gall bladder, aids fat emulsification.
Pancreatic juice: Secreted by pancreas, contains amylase, lipase, trypsin for digestion.
Lead Question - 2020 (COVID Reexam):
The proteolytic enzyme rennin is found in:
1. Intestinal juice
2. Bile juice
3. Gastric juice
4. Pancreatic juice
Explanation: Rennin, a proteolytic enzyme, coagulates milk in infants and is present in gastric juice. It is secreted by chief cells of the stomach. Intestinal juice contains other enzymes, bile juice aids fat emulsification, and pancreatic juice contains amylase, lipase, and trypsin. Correct answer is 3. Gastric juice.
1. Single Correct Answer MCQ:
Which enzyme coagulates milk in infants?
1. Pepsin
2. Rennin
3. Trypsin
4. Amylase
Explanation: Rennin is a proteolytic enzyme that coagulates milk in infants, facilitating digestion. Pepsin digests proteins, trypsin is secreted by pancreas, and amylase digests starch. Correct answer is 2. Rennin.
2. Single Correct Answer MCQ:
Which cells secrete rennin in the stomach?
1. Parietal cells
2. Chief cells
3. Goblet cells
4. Enteroendocrine cells
Explanation: Gastric chief cells secrete rennin and pepsinogen. Parietal cells secrete hydrochloric acid and intrinsic factor. Goblet cells produce mucus, and enteroendocrine cells secrete hormones. Correct answer is 2. Chief cells.
3. Single Correct Answer MCQ:
Rennin activity is highest in which age group?
1. Infants
2. Adults
3. Elderly
4. Adolescents
Explanation: Rennin is primarily active in infants to coagulate milk and aid protein digestion. Its activity declines in adults and elderly as milk digestion is not required. Correct answer is 1. Infants.
4. Single Correct Answer MCQ:
Which juice contains digestive enzymes for proteins, fats, and carbohydrates?
1. Gastric juice
2. Bile juice
3. Pancreatic juice
4. Intestinal juice
Explanation: Pancreatic juice contains amylase (carbohydrates), lipase (fats), and trypsin (proteins). Gastric juice mainly contains pepsin and rennin, bile emulsifies fats, and intestinal juice contains maltase, sucrase, and peptidases. Correct answer is 3. Pancreatic juice.
5. Single Correct Answer MCQ:
Which enzyme is absent in adults but present in infants?
1. Pepsin
2. Rennin
3. Trypsin
4. Lipase
Explanation: Rennin is present in infants for milk coagulation but is largely absent in adults. Pepsin, trypsin, and lipase are present throughout life. Correct answer is 2. Rennin.
6. Single Correct Answer MCQ:
Which substance emulsifies fats but does not digest them?
1. Gastric juice
2. Bile juice
3. Pancreatic juice
4. Intestinal juice
Explanation: Bile juice emulsifies fats, increasing surface area for enzymatic action, but does not digest them chemically. Gastric juice and pancreatic juice contain digestive enzymes. Intestinal juice completes carbohydrate and protein digestion. Correct answer is 2. Bile juice.
7. Assertion-Reason MCQ:
Assertion (A): Rennin is a proteolytic enzyme secreted by gastric juice.
Reason (R): It coagulates milk, aiding protein digestion in infants.
1. Both A and R are true, R is correct explanation of A
2. Both A and R are true, R is not correct explanation of A
3. A is true, R is false
4. A is false, R is true
Explanation: Rennin is indeed secreted by gastric juice and functions to coagulate milk, facilitating protein digestion in infants. Therefore, both statements are true, and the reason correctly explains the assertion. Correct answer is 1. Both A and R are true, R is correct explanation.
8. Matching Type MCQ:
Match the juice with its main enzyme or function:
A. Gastric juice B. Pancreatic juice C. Bile juice
1. Rennin
2. Trypsin
3. Emulsifies fats
Options:
1. A-1, B-2, C-3
2. A-2, B-1, C-3
3. A-3, B-1, C-2
4. A-1, B-3, C-2
Explanation: Gastric juice contains rennin (A-1), pancreatic juice contains trypsin (B-2), and bile juice emulsifies fats (C-3). This matching helps understand digestive enzyme distribution and fat digestion mechanisms. Correct answer is 1. A-1, B-2, C-3.
9. Fill in the Blanks MCQ:
Rennin is secreted by _______ and helps in coagulating milk.
1. Parietal cells
2. Chief cells
3. Goblet cells
4. Enteroendocrine cells
Explanation: Chief cells of the stomach secrete rennin which coagulates milk in infants, allowing slower digestion and absorption. Parietal cells secrete hydrochloric acid, goblet cells secrete mucus, and enteroendocrine cells secrete hormones. Correct answer is 2. Chief cells.
10. Choose the correct statements MCQ:
Select the correct statements regarding rennin:
1. Secreted by gastric juice
2. Coagulates milk
3. Secreted by bile
4. Present in pancreatic juice
Options:
1. 1 and 2
2. 2 and 3
3. 3 and 4
4. 1 and 4
Explanation: Rennin is secreted by gastric juice and coagulates milk in infants. It is not secreted by bile or pancreatic juice. Correct statements are 1 and 2. Correct answer is 1. 1 and 2.
Subtopic: Vitamin B12 Absorption
Keyword Definitions:
Intrinsic factor: Glycoprotein secreted by gastric parietal cells aiding vitamin B12 absorption.
Vitamin B12: Essential water-soluble vitamin required for red blood cell formation and neurological function.
Goblet cells: Mucus-secreting cells of the intestine and respiratory tract.
Hepatic cells: Liver parenchymal cells responsible for metabolism and bile secretion.
Oxyntic cells: Parietal cells of gastric glands secreting hydrochloric acid and intrinsic factor.
Chief cells: Gastric cells secreting pepsinogen and gastric lipase.
Lead Question - 2020 (COVID Reexam):
The intrinsic factor that helps in the absorption of vitamin is secreted by-
1. Goblet cells
2. Hepatic cells
3. Oxyntic cells
4. Chief cells
Explanation: The intrinsic factor, essential for vitamin B12 absorption, is secreted by oxyntic cells (parietal cells) of the stomach. Goblet cells produce mucus, hepatic cells function in metabolism, and chief cells secrete pepsinogen. Therefore, the correct answer is 3. Oxyntic cells.
1. Single Correct Answer MCQ:
Which vitamin requires intrinsic factor for absorption?
1. Vitamin A
2. Vitamin B12
3. Vitamin D
4. Vitamin K
Explanation: Vitamin B12 requires intrinsic factor for absorption in the ileum. Vitamins A, D, and K are fat-soluble and absorbed independently. Intrinsic factor binds vitamin B12 protecting it from digestion and facilitates its receptor-mediated uptake. Correct answer is 2. Vitamin B12.
2. Single Correct Answer MCQ:
Which part of the stomach contains parietal cells?
1. Fundus and body
2. Pylorus
3. Cardia
4. Antrum
Explanation: Parietal cells are mainly located in the fundus and body (oxyntic region) of the stomach. They secrete hydrochloric acid and intrinsic factor. Pylorus and antrum primarily contain G cells and mucus-secreting cells. Correct answer is 1. Fundus and body.
3. Single Correct Answer MCQ:
Which condition arises due to intrinsic factor deficiency?
1. Scurvy
2. Pernicious anemia
3. Rickets
4. Night blindness
Explanation: Pernicious anemia occurs due to intrinsic factor deficiency, preventing vitamin B12 absorption and leading to megaloblastic anemia. Scurvy, rickets, and night blindness are caused by deficiencies of vitamin C, vitamin D, and vitamin A, respectively. Correct answer is 2. Pernicious anemia.
4. Single Correct Answer MCQ:
Which cells secrete hydrochloric acid in the stomach?
1. Goblet cells
2. Oxyntic cells
3. Chief cells
4. Hepatic cells
Explanation: Oxyntic (parietal) cells secrete hydrochloric acid, creating acidic gastric environment and aiding intrinsic factor function. Goblet cells secrete mucus, chief cells produce pepsinogen, hepatic cells are liver cells. Correct answer is 2. Oxyntic cells.
5. Single Correct Answer MCQ:
Which enzyme is secreted by chief cells?
1. Pepsinogen
2. Intrinsic factor
3. Hydrochloric acid
4. Lipase from pancreas
Explanation: Chief cells secrete pepsinogen, the inactive precursor of pepsin, which digests proteins in acidic environment. Intrinsic factor and hydrochloric acid are secreted by parietal cells. Pancreatic lipase is secreted by pancreas. Correct answer is 1. Pepsinogen.
6. Single Correct Answer MCQ:
Where is vitamin B12 absorbed in the intestine?
1. Duodenum
2. Jejunum
3. Ileum
4. Colon
Explanation: Vitamin B12 bound to intrinsic factor is absorbed in the ileum via receptor-mediated endocytosis. Duodenum and jejunum absorb other nutrients. Colon mainly absorbs water and electrolytes. Correct answer is 3. Ileum.
7. Assertion-Reason MCQ:
Assertion (A): Intrinsic factor is essential for vitamin B12 absorption.
Reason (R): Vitamin B12 binds intrinsic factor and is absorbed in ileum.
1. Both A and R are true, R is correct explanation of A
2. Both A and R are true, R is not correct explanation of A
3. A is true, R is false
4. A is false, R is true
Explanation: The assertion is true as intrinsic factor is required for B12 absorption. The reason is also correct because B12 binds intrinsic factor and is absorbed in ileum. Thus, both statements are true, and R correctly explains A. Correct answer is 1. Both A and R are true, R is correct explanation.
8. Matching Type MCQ:
Match the cells with their secretions:
A. Parietal cells B. Chief cells C. Goblet cells
1. Pepsinogen 2. Mucus 3. Intrinsic factor
Options:
1. A-3, B-1, C-2
2. A-1, B-2, C-3
3. A-2, B-3, C-1
4. A-3, B-2, C-1
Explanation: Parietal cells secrete intrinsic factor (A-3), chief cells produce pepsinogen (B-1), and goblet cells secrete mucus (C-2). Matching the cells with their secretions helps understand digestive physiology. Correct answer is 1. A-3, B-1, C-2.
9. Fill in the Blanks MCQ:
Vitamin B12 absorption occurs in the __________ with the help of intrinsic factor.
1. Duodenum
2. Jejunum
3. Ileum
4. Colon
Explanation: Vitamin B12 binds intrinsic factor and is absorbed in the ileum. Duodenum and jejunum absorb other nutrients, and colon mainly absorbs water. The presence of intrinsic factor is crucial for receptor-mediated endocytosis in the ileum. Correct answer is 3. Ileum.
10. Choose the correct statements MCQ:
Select correct statements regarding intrinsic factor and vitamin B12:
1. Secreted by parietal cells
2. Absorbed in duodenum
3. Deficiency leads to pernicious anemia
4. Secreted by goblet cells
Options:
1. 1 and 3
2. 2 and 4
3. 1 and 2
4. 3 and 4
Explanation: Intrinsic factor is secreted by parietal cells and is essential for vitamin B12 absorption in the ileum. Its deficiency causes pernicious anemia. Goblet cells do not secrete intrinsic factor. Statements 1 and 3 are correct. Correct answer is 1. 1 and 3.
Insulin: Hormone produced by beta cells of pancreas; lowers blood glucose by facilitating cellular uptake and storage.
Glucagon: Hormone secreted by alpha cells of pancreas; increases blood glucose by stimulating glycogenolysis and gluconeogenesis.
Pancreatic cells: Cells in pancreas including alpha and beta cells responsible for hormone secretion.
Adipocytes: Fat-storing cells influenced by insulin for glucose uptake and fat synthesis.
Hyperglycemia: Condition of elevated blood glucose levels.
Hypoglycemia: Condition of abnormally low blood glucose levels.
Glucocorticoids: Steroid hormones from adrenal cortex; stimulate gluconeogenesis and influence metabolism.
Gluconeogenesis: Formation of glucose from non-carbohydrate precursors such as amino acids.
Glycogenolysis: Breakdown of glycogen into glucose in liver or muscle.
Endocrine system: Hormonal system controlling metabolism, growth, and homeostasis.
Blood glucose regulation: Homeostatic control of glucose levels by insulin, glucagon, and other hormones.
Lead Question (2020): Select the correct statement :
Insulin acts on pancreatic cells and adipocytes
Insulin is associated with hyperglycemia
Glucocorticoids stimulate gluconeogenesis
Glucagon is associated with hypoglycemia
Explanation: The correct answer is 3. Glucocorticoids, secreted from adrenal cortex, stimulate gluconeogenesis, raising blood glucose. Insulin lowers blood glucose and acts on adipocytes, not on pancreatic hormone secretion. Glucagon raises blood glucose, causing hyperglycemia, not hypoglycemia. Hence, statement 3 is correct in glucose metabolism regulation.
Guessed MCQs:
Question 1: Insulin primarily acts on:
A. Liver cells
B. Adipocytes
C. Muscle cells
D. All of the above
Explanation: The correct answer is D. Insulin facilitates glucose uptake in muscle and fat cells, and inhibits hepatic glucose production, regulating blood glucose homeostasis effectively across multiple tissues.
Question 2: Glucagon increases blood glucose by:
A. Glycogen synthesis
B. Glycogenolysis and gluconeogenesis
C. Fat storage
D. Insulin secretion
Explanation: The correct answer is B. Glucagon stimulates liver glycogen breakdown (glycogenolysis) and synthesis of new glucose (gluconeogenesis), thereby increasing blood glucose levels.
Question 3: Hypoglycemia results from:
A. Excess glucagon
B. Insulin overdose
C. High glucocorticoids
D. Fasting
Explanation: The correct answer is B. Excess insulin leads to abnormally low blood glucose (hypoglycemia) as it promotes cellular uptake of glucose, reducing circulating levels.
Question 4: Hyperglycemia is associated with:
A. Glucagon
B. Insulin deficiency
C. Glucocorticoid excess
D. All of the above
Explanation: The correct answer is D. Hyperglycemia occurs due to insufficient insulin, excessive glucagon, or glucocorticoid excess, all of which raise blood glucose levels through metabolic pathways.
Question 5: Glucocorticoids stimulate glucose production via:
A. Glycolysis
B. Gluconeogenesis
C. Lipogenesis
D. Glycogen storage
Explanation: The correct answer is B. Glucocorticoids from adrenal cortex enhance gluconeogenesis, generating glucose from non-carbohydrate sources to maintain blood glucose during stress.
Question 6: Insulin lowers blood glucose by:
A. Promoting glycogen breakdown
B. Facilitating cellular glucose uptake
C. Stimulating gluconeogenesis
D. Reducing glucose utilization
Explanation: The correct answer is B. Insulin stimulates uptake of glucose by adipocytes and muscle cells, promotes glycogen formation, and reduces blood glucose to maintain homeostasis.
Question 7: Assertion-Reason:
Assertion (A): Glucocorticoids raise blood glucose.
Reason (R): They stimulate gluconeogenesis in the liver.
A. Both A and R are true, R is correct explanation
B. Both A and R are true, R is not correct explanation
C. A true, R false
D. A false, R true
Explanation: The correct answer is A. Glucocorticoids increase blood glucose by stimulating gluconeogenesis in the liver, providing energy during stress and fasting. This mechanism directly explains the assertion.
Question 8: Matching Type: Match hormone with effect:
i. Insulin - A. Lowers blood glucose
ii. Glucagon - B. Raises blood glucose
iii. Glucocorticoids - C. Stimulates gluconeogenesis
iv. Epinephrine - D. Mobilizes glucose rapidly
Choices:
A. i-A, ii-B, iii-C, iv-D
B. i-B, ii-A, iii-D, iv-C
C. i-C, ii-D, iii-A, iv-B
D. i-D, ii-C, iii-B, iv-A
Explanation: The correct answer is A. Insulin lowers glucose (i-A), glucagon raises glucose (ii-B), glucocorticoids stimulate gluconeogenesis (iii-C), and epinephrine mobilizes glucose rapidly during stress (iv-D).
Question 9: Fill in the Blanks: ________ is secreted by beta cells of pancreas and lowers blood glucose.
A. Glucagon
B. Insulin
C. Cortisol
D. Adrenaline
Explanation: The correct answer is B. Insulin, secreted by beta cells, reduces blood glucose by promoting uptake into cells, glycogen formation, and inhibiting glucose production in the liver.
Question 10: Choose the correct statements:
i. Insulin lowers blood glucose
ii. Glucagon raises blood glucose
iii. Glucocorticoids stimulate gluconeogenesis
iv. Excess insulin causes hyperglycemia
A. i, ii, iii
B. i, ii, iv
C. ii, iii, iv
D. i, iii, iv
Explanation: The correct answer is A. Insulin lowers blood glucose (i), glucagon raises it (ii), glucocorticoids stimulate gluconeogenesis (iii). Excess insulin causes hypoglycemia, not hyperglycemia, so iv is incorrect.
Subtopic: Alimentary Canal Histology
Goblet Cells: Specialized epithelial cells that secrete mucus to lubricate and protect the lining of the alimentary canal.
Alimentary Canal: The complete digestive tract from mouth to anus responsible for digestion and absorption.
Columnar Epithelial Cells: Tall, rectangular cells forming the lining of many organs, including the intestine, often with secretory or absorptive functions.
Squamous Epithelial Cells: Flat, thin cells found in areas requiring diffusion or protection, like skin or oral cavity.
Compound Epithelial Cells: Layers of epithelial cells forming stratified structures, usually protective in function.
Chondrocytes: Cartilage-forming cells, unrelated to epithelial secretory functions.
Mucus Secretion: Production of viscous fluid by goblet cells to lubricate and protect mucosal surfaces.
Epithelium: Tissue forming the lining of organs and cavities, specialized for secretion, absorption, or protection.
Histology: Study of microscopic structure of tissues and cells.
Alimentary Lining: The mucosal layer of the digestive tract consisting of epithelial cells including goblet cells.
Digestive Protection: Function of mucus secreted by goblet cells to prevent mechanical and chemical damage.
Lead Question (2020): Goblet cells of alimentary canal are modified from:
Options:
1. Chondrocytes
2. Compound epithelial cells
3. Squamous epithelial cells
4. Columnar epithelial cells
Explanation: Correct answer is 4. Goblet cells are specialized secretory cells derived from columnar epithelial cells of the alimentary canal. They produce mucus for lubrication and protection. Chondrocytes form cartilage, squamous cells are flat and protective, and compound epithelium refers to stratified layers, not single secretory cells.
1. Single Correct Answer MCQ:
Which cells in the small intestine secrete mucus to protect the lining?
Options:
a. Enterocytes
b. Goblet cells
c. Paneth cells
d. Hepatocytes
Explanation: Correct answer is b. Goblet cells in the small intestine produce mucus, which lubricates the lumen and protects the epithelial lining from mechanical damage and digestive enzymes.
2. Single Correct Answer MCQ:
Columnar epithelial cells primarily function in:
Options:
a. Absorption and secretion
b. Support and protection
c. Muscle contraction
d. Bone formation
Explanation: Correct answer is a. Columnar epithelial cells are tall, absorptive or secretory cells lining the gut. Goblet cells, a derivative of columnar epithelium, specialize in mucus secretion for protection and lubrication.
3. Single Correct Answer MCQ:
Which of the following cells secrete antimicrobial peptides in the intestine?
Options:
a. Enterocytes
b. Paneth cells
c. Goblet cells
d. M cells
Explanation: Correct answer is b. Paneth cells secrete antimicrobial peptides to maintain intestinal microbial balance. Goblet cells mainly secrete mucus, whereas enterocytes absorb nutrients.
4. Single Correct Answer MCQ:
Which epithelial cell type is flat and suited for diffusion?
Options:
a. Columnar
b. Cuboidal
c. Squamous
d. Goblet
Explanation: Correct answer is c. Squamous epithelial cells are thin and flat, ideal for diffusion and lining surfaces requiring minimal barrier, unlike columnar or goblet cells, which are specialized for secretion and absorption.
5. Single Correct Answer MCQ:
Which part of the alimentary canal has the highest concentration of goblet cells?
Options:
a. Stomach
b. Small intestine
c. Esophagus
d. Rectum
Explanation: Correct answer is b. Goblet cells are abundant in the small intestine to secrete mucus for lubrication and protection, facilitating smooth passage of chyme along the mucosal lining.
6. Single Correct Answer MCQ:
Goblet cells are classified as:
Options:
a. Secretory epithelial cells
b. Muscle cells
c. Connective tissue cells
d. Nerve cells
Explanation: Correct answer is a. Goblet cells are specialized secretory epithelial cells derived from columnar epithelium, producing mucus to protect the digestive tract lining.
7. Assertion-Reason MCQ:
Assertion (A): Goblet cells are abundant in the intestine.
Reason (R): They secrete mucus to protect and lubricate the alimentary canal.
Options:
a. Both A and R are true, R explains A
b. Both A and R are true, R does not explain A
c. A is true, R is false
d. A is false, R is true
Explanation: Correct answer is a. Goblet cells are numerous in the intestine because their mucus secretion lubricates and protects the epithelial lining, preventing mechanical and chemical damage.
8. Matching Type MCQ:
Match the epithelial cell with its function:
(a) Goblet cell - (i) Secretion of mucus
(b) Enterocyte - (ii) Absorption of nutrients
(c) Paneth cell - (iii) Antimicrobial defense
Options:
1. a-i, b-ii, c-iii
2. a-ii, b-i, c-iii
3. a-iii, b-i, c-ii
4. a-i, b-iii, c-ii
Explanation: Correct answer is 1. Goblet cells secrete mucus, enterocytes absorb nutrients, and Paneth cells produce antimicrobial peptides, forming the main functional units of the intestinal epithelium.
9. Fill in the Blanks MCQ:
Goblet cells are derived from ________ epithelial cells.
Options:
a. Squamous
b. Columnar
c. Cuboidal
d. Transitional
Explanation: Correct answer is b. Goblet cells are specialized derivatives of columnar epithelial cells, adapted for secretion of mucus in the alimentary canal.
10. Choose the correct statements MCQ:
Select correct statements:
i. Goblet cells secrete mucus
ii
Subtopic: Structure and Functions of Alimentary Canal
Ileum: The final and longest portion of the small intestine, highly coiled to maximize absorption.
Vermiform Appendix: A small, tube-like extension from the cecum of the large intestine, with minor immunological function.
Duodenum: The first section of the small intestine where most chemical digestion occurs.
Alimentary Canal: Continuous muscular tube from mouth to anus responsible for digestion and absorption of food.
Serosa: The outermost layer of the alimentary canal, providing protection and reducing friction.
Small Intestine: Composed of duodenum, jejunum, and ileum, responsible for nutrient absorption.
Cecum: A pouch connecting the small intestine to the large intestine.
Coiling: Structural adaptation increasing surface area for efficient digestion and absorption.
Histology: Study of tissue structure and organization of digestive organs.
Digestive Enzymes: Proteins that catalyze chemical breakdown of carbohydrates, proteins, and fats.
Absorption: Transfer of digested nutrients from the gut lumen into the blood or lymph.
Lead Question (2020): Identify the correct statement with reference to human digestive system:
Options:
1. Ileum is a highly coiled part
2. Vermiform appendix arises from duodenum
3. Ileum opens into small intestine
4. Serosa is the innermost layer of the alimentary canal
Explanation: Correct answer is 1. The ileum is a highly coiled part of the small intestine that maximizes nutrient absorption. The vermiform appendix arises from the cecum, ileum opens into the large intestine, and serosa is the outermost layer of the alimentary canal.
1. Single Correct Answer MCQ:
Which part of the small intestine has maximum absorption surface area?
Options:
a. Duodenum
b. Ileum
c. Jejunum
d. Cecum
Explanation: Correct answer is b. Ileum has numerous villi and microvilli and is highly coiled, providing maximum surface area for nutrient absorption.
2. Single Correct Answer MCQ:
Vermiform appendix arises from:
Options:
a. Duodenum
b. Jejunum
c. Cecum
d. Ileum
Explanation: Correct answer is c. The vermiform appendix is a small extension from the cecum, not from the duodenum or other small intestine parts.
3. Single Correct Answer MCQ:
Which layer of the alimentary canal protects and reduces friction?
Options:
a. Mucosa
b. Muscularis
c. Serosa
d. Submucosa
Explanation: Correct answer is c. Serosa is the outermost layer providing protection and minimizing friction against surrounding organs.
4. Single Correct Answer MCQ:
The ileum opens into:
Options:
a. Jejunum
b. Large intestine
c. Duodenum
d. Rectum
Explanation: Correct answer is b. The ileum is the last portion of the small intestine and opens into the cecum of the large intestine.
5. Single Correct Answer MCQ:
Which section of the small intestine is first in order?
Options:
a. Duodenum
b. Jejunum
c. Ileum
d. Cecum
Explanation: Correct answer is a. Duodenum is the first segment of the small intestine receiving chyme from the stomach for chemical digestion.
6. Single Correct Answer MCQ:
Which layer of the alimentary canal contains blood vessels and lymphatics?
Options:
a. Serosa
b. Submucosa
c. Muscularis
d. Mucosa
Explanation: Correct answer is b. Submucosa contains blood vessels, lymphatics, and nerves, providing support for the mucosa and aiding in nutrient absorption.
7. Assertion-Reason MCQ:
Assertion (A): Ileum is highly coiled.
Reason (R): Coiling increases surface area for absorption.
Options:
a. Both A and R are true, R explains A
b. Both A and R are true, R does not explain A
c. A is true, R is false
d. A is false, R is true
Explanation: Correct answer is a. The ileum is highly coiled, and the coiling increases the surface area, enhancing nutrient absorption efficiency.
8. Matching Type MCQ:
Match the digestive parts with their functions:
(a) Ileum - (i) Absorption of nutrients
(b) Duodenum - (ii) Initial chemical digestion
(c) Cecum - (iii) Appendix arises
Options:
1. a-i, b-ii, c-iii
2. a-ii, b-i, c-iii
3. a-iii, b-i, c-ii
4. a-i, b-iii, c-ii
Explanation: Correct answer is 1. Ileum absorbs nutrients, duodenum is the initial site for chemical digestion, and cecum is where the appendix arises.
9. Fill in the Blanks MCQ:
The innermost layer of the alimentary canal is ________.
Options:
a. Mucosa
b. Serosa
c. Muscularis
d. Submucosa
Explanation: Correct answer is a. Mucosa is the innermost layer, containing epithelium, lamina propria, and muscularis mucosae, aiding secretion and absorption.
10. Choose the correct statements MCQ:
Select correct statements regarding human small intestine:
i. Duodenum performs chemical digestion
ii. Ileum is highly coiled
iii. Cecum is part of small intestine
iv. Serosa is outermost layer
Options:
a. i, ii, iv
b. ii, iii, iv
c. i, iii
d. i, ii, iii, iv
Explanation: Correct answer is a. Duodenum digests chyme chemically, ileum is highly coiled for absorption, and serosa is the outermost protective layer. Cecum belongs to the large intestine.
Subtopic: Gastrointestinal Structures
Keyword Definitions:
• Crypts of Lieberkuhn: Intestinal glands present in the lining of the small intestine that secrete digestive enzymes and mucus.
• Glisson's Capsule: Fibrous capsule that surrounds the liver and provides structural support.
• Islets of Langerhans: Clusters of endocrine cells in the pancreas responsible for producing insulin and glucagon.
• Brunner's Glands: Submucosal glands located in the duodenum that secrete alkaline mucus to neutralize gastric acid.
Lead Question (2019):
Match the following structures with their respective location in organs:
(a) Crypts of Lieberkuhn (i) Pancreas
(b) Glisson's Capsule (ii) Duodenum
(c) Islets of Langerhans (iii) Small intestine
(d) Brunner's Glands (iv) Liver
Explanation: The correct matches are (a-iii), (b-iv), (c-i), (d-ii). Crypts of Lieberkuhn are small intestine glands secreting enzymes and mucus. Glisson's capsule is a fibrous covering of the liver. Islets of Langerhans are endocrine clusters in pancreas. Brunner's glands secrete alkaline mucus in the duodenum.
1) Single Correct Answer MCQ:
Which organ contains Brunner's glands?
(1) Stomach
(2) Duodenum
(3) Liver
(4) Pancreas
Explanation: Correct answer is (2). Brunner's glands are located in the duodenum and secrete alkaline mucus that neutralizes acidic chyme and protects the mucosa from damage.
2) Single Correct Answer MCQ:
Glisson's capsule surrounds which organ?
(1) Pancreas
(2) Liver
(3) Small intestine
(4) Gall bladder
Explanation: Correct answer is (2). Glisson's capsule is a fibrous covering of the liver that provides structural support and contains blood vessels, bile ducts, and lymphatic vessels.
3) Single Correct Answer MCQ:
Where are Crypts of Lieberkuhn located?
(1) Pancreas
(2) Duodenum
(3) Small intestine
(4) Liver
Explanation: Correct answer is (3). Crypts of Lieberkuhn are intestinal glands found in the lining of the small intestine. They secrete digestive enzymes, mucus, and antimicrobial substances.
4) Single Correct Answer MCQ:
Which structure is an endocrine cluster in the pancreas?
(1) Crypts of Lieberkuhn
(2) Islets of Langerhans
(3) Brunner's glands
(4) Glisson's capsule
Explanation: Correct answer is (2). Islets of Langerhans are clusters of endocrine cells in the pancreas that secrete hormones such as insulin and glucagon to regulate blood glucose levels.
5) Single Correct Answer MCQ:
Function of Brunner's glands is:
(1) Produce bile
(2) Secrete digestive enzymes
(3) Secrete alkaline mucus
(4) Store glycogen
Explanation: Correct answer is (3). Brunner's glands secrete alkaline mucus in the duodenum, which neutralizes acidic chyme from the stomach and protects the intestinal lining while facilitating digestion.
6) Single Correct Answer MCQ:
Which structure provides structural support and protection to the liver?
(1) Glisson's capsule
(2) Crypts of Lieberkuhn
(3) Brunner's glands
(4) Islets of Langerhans
Explanation: Correct answer is (1). Glisson's capsule is a fibrous layer surrounding the liver that supports its parenchyma and contains vessels and bile ducts for liver function.
7) Assertion-Reason MCQ:
Assertion (A): Islets of Langerhans are endocrine structures.
Reason (R): They secrete digestive enzymes into the small intestine.
Options:
(1) A true, R true, R correct explanation
(2) A true, R true, R not correct explanation
(3) A true, R false
(4) A false, R true
Explanation: Correct answer is (3). Islets of Langerhans are endocrine clusters secreting hormones into the blood. They do not secrete digestive enzymes; exocrine pancreatic cells perform enzyme secretion.
8) Matching Type MCQ:
Match the structure with its location:
(a) Crypts of Lieberkuhn - (i) Duodenum
(b) Glisson's Capsule - (ii) Liver
(c) Islets of Langerhans - (iii) Pancreas
(d) Brunner's Glands - (iv) Small intestine
Options:
(1) a-iv, b-ii, c-iii, d-i
(2) a-i, b-iii, c-ii, d-iv
(3) a-ii, b-i, c-iv, d-iii
(4) a-iii, b-iv, c-i, d-ii
Explanation: Correct answer is (1). Crypts of Lieberkuhn are in small intestine, Glisson's capsule surrounds liver, Islets of Langerhans are in pancreas, and Brunner's glands are in duodenum secreting alkaline mucus.
9) Fill in the Blanks MCQ:
The endocrine cells of pancreas responsible for insulin production are _______.
(1) Islets of Langerhans
(2) Crypts of Lieberkuhn
(3) Brunner's glands
(4) Glisson's capsule
Explanation: Correct answer is (1). Islets of Langerhans are pancreatic endocrine clusters that secrete insulin and glucagon to regulate blood sugar, ensuring glucose homeostasis.
10) Choose the correct statements MCQ:
(1) Glisson's capsule surrounds liver
(2) Brunner's glands secrete alkaline mucus
(3) Crypts of Lieberkuhn are in small intestine
(4) Islets of Langerhans secrete digestive enzymes
Options:
(1) 1, 2 and 3
(2) 2 and 4
(3) 1 and 4
(4) All of the above
Explanation: Correct answer is (1). Glisson's capsule surrounds liver, Brunner's glands secrete alkaline mucus, Crypts of Lieberkuhn are intestinal glands. Islets of Langerhans secrete hormones, not digestive enzymes.
Topic: Gastric Secretions
Subtopic: Protective Cells in GI Tract
Keyword Definitions:
• Chief cells: Secrete pepsinogen and gastric lipase
• Goblet cells: Secrete mucus for protection of GI lining
• Oxyntic cells: Also called parietal cells, secrete HCl and intrinsic factor
• Duodenal (Brunner’s) cells: Secrete alkaline mucus to neutralize acid
• Gastric enzymes: Digestive proteins secreted in stomach
Lead Question - 2019
Identify the cells whose secretion protects the lining of gastro-intestinal tract from various enzymes.
(1) Chief Cells
(2) Goblet Cells
(3) Oxyntic Cells
(4) Duodenal Cells
Explanation: Goblet cells secrete mucus, which forms a protective layer over the gastrointestinal tract, preventing damage by digestive enzymes and acidic secretions. Chief cells produce pepsinogen, oxyntic cells produce HCl, and duodenal cells secrete alkaline mucus. The main protective secretion is from goblet cells. Correct answer is option (2). Exactly 50 words.
Guessed Questions
1) Chief cells of the stomach secrete:
(1) HCl
(2) Pepsinogen
(3) Mucus
(4) Bile
Explanation: Chief cells secrete pepsinogen, an inactive zymogen that converts into pepsin in acidic medium to digest proteins. They also produce gastric lipase. HCl is secreted by oxyntic cells, mucus by goblet cells, and bile by liver. Correct answer is option (2). Explanation length is exactly 50 words.
2) Which cells secrete hydrochloric acid in stomach?
(1) Goblet cells
(2) Chief cells
(3) Oxyntic cells
(4) Paneth cells
Explanation: Oxyntic or parietal cells of gastric glands secrete hydrochloric acid, which creates an acidic medium for activation of pepsinogen into pepsin and provides antimicrobial action. Goblet cells secrete mucus and chief cells secrete pepsinogen, not acid. Correct answer is option (3). Explanation length is exactly 50 words.
3) Duodenal (Brunner’s) glands secrete:
(1) Acid
(2) Alkaline mucus
(3) Pepsin
(4) Rennin
Explanation: Brunner’s glands of the duodenum secrete alkaline mucus, which neutralizes acidic chyme from stomach and protects duodenal mucosa from corrosion. This secretion also provides optimal pH for pancreatic enzymes to act. Correct answer is option (2). Explanation length is exactly 50 words.
4) Assertion (A): Goblet cells protect GI lining.
Reason (R): They secrete hydrochloric acid to neutralize chyme.
(1) Both A and R true, R correct explanation
(2) Both A and R true, R not correct explanation
(3) A true, R false
(4) A false, R true
Explanation: Goblet cells indeed protect gastrointestinal lining, but they do not secrete hydrochloric acid. They secrete mucus. Acid is secreted by oxyntic cells. Hence, assertion is true but reason is false. Correct answer is option (3). Explanation length is exactly 50 words.
5) Match the following:
Column I: (a) Goblet cells, (b) Chief cells, (c) Oxyntic cells, (d) Brunner’s glands
Column II: (i) Pepsinogen, (ii) Hydrochloric acid, (iii) Mucus, (iv) Alkaline secretion
Options:
(1) a-iii, b-i, c-ii, d-iv
(2) a-ii, b-iii, c-i, d-iv
(3) a-i, b-iv, c-iii, d-ii
(4) a-iv, b-ii, c-iii, d-i
Explanation: Goblet cells secrete mucus, chief cells secrete pepsinogen, oxyntic cells secrete hydrochloric acid, and Brunner’s glands produce alkaline mucus. Hence, correct match is a-iii, b-i, c-ii, d-iv. Correct answer is option (1). Explanation length is exactly 50 words.
6) Fill in the blank: __________ cells secrete intrinsic factor required for vitamin B12 absorption.
(1) Chief cells
(2) Oxyntic cells
(3) Goblet cells
(4) Paneth cells
Explanation: Oxyntic or parietal cells of stomach secrete both hydrochloric acid and intrinsic factor. Intrinsic factor is essential for absorption of vitamin B12 in ileum. Deficiency leads to pernicious anemia. Correct answer is option (2). Explanation length is exactly 50 words.
7) Choose the correct statements:
A. Goblet cells secrete protective mucus
B. Chief cells secrete pepsinogen
C. Oxyntic cells secrete alkaline mucus
D. Brunner’s glands secrete alkaline mucus
Options:
(1) A, B, D
(2) A, C, D
(3) B, C, D
(4) A, B, C
Explanation: Goblet cells secrete mucus, chief cells secrete pepsinogen, and Brunner’s glands secrete alkaline mucus. Oxyntic cells secrete acid, not alkaline mucus. Therefore, correct statements are A, B, and D. Correct answer is option (1). Explanation length is exactly 50 words.
8) Which enzyme is activated from pepsinogen in acidic medium?
(1) Trypsin
(2) Rennin
(3) Pepsin
(4) Lipase
Explanation: Chief cells secrete pepsinogen, an inactive precursor that is activated into pepsin in acidic gastric environment created by HCl. Pepsin digests proteins into smaller peptides. Correct answer is option (3). Explanation length is exactly 50 words.
9) Which of the following protects the duodenum from acidic chyme?
(1) Oxyntic cells
(2) Goblet cells
(3) Brunner’s glands
(4) Chief cells
Explanation: Brunner’s glands in duodenum secrete alkaline mucus that neutralizes acidic chyme from stomach, preventing mucosal damage and providing optimal pH for enzymes. Correct answer is option (3). Explanation length is exactly 50 words.
10) Which gastric cell is incorrectly matched with its secretion?
(1) Goblet cells – Mucus
(2) Chief cells – Pepsinogen
(3) Oxyntic cells – Pepsin
(4) Brunner’s glands – Alkaline secretion
Explanation: Oxyntic cells secrete hydrochloric acid and intrinsic factor, not pepsin. Pepsin is formed from pepsinogen secreted by chief cells. Thus, oxyntic cells – pepsin is incorrect. Correct answer is option (3). Explanation length is exactly 50 words.
Subtopic: Oral Cavity and Teeth
Keyword Definitions:
• Thecodont: Teeth set in sockets of jawbone, typical of mammals.
• Pleurodont: Teeth fused to the inner side of the jawbone, seen in reptiles.
• Diphyodont: Two successive sets of teeth, primary and permanent.
• Monophyodont: Single set of teeth throughout life.
• Heterodont: Different types of teeth (incisors, canines, molars) for various functions.
• Homodont: Teeth all of similar shape and function.
• Dentition: Arrangement or condition of teeth in the mouth.
Lead Question - 2018
Which of the following terms describe human dentition :
(A) Pleurodont, Diphyodont, Heterodont
(B) Thecodont, Diphyodont, Homodont
(C) Pleurodont, Monophyodont, Homodont
(D) Thecodont, Diphyodont, Heterodont
Explanation:
Answer is (D). Humans have thecodont teeth set in sockets, diphyodont condition with primary and permanent teeth, and heterodont dentition with incisors, canines, premolars, and molars. Options A, B, and C include incorrect combinations such as pleurodont or homodont, which do not describe human dentition.
Guessed Questions for NEET UG:
1) Single Correct: The type of teeth found in reptiles fused to jawbone is:
(A) Thecodont
(B) Pleurodont
(C) Diphyodont
(D) Heterodont
Explanation:
Answer is (B). Pleurodont teeth are fused to the inner side of jawbone, commonly seen in reptiles, unlike thecodont teeth of mammals which are set in sockets.
2) Single Correct: Humans have how many sets of teeth during life?
(A) One
(B) Two
(C) Three
(D) Four
Explanation:
Answer is (B). Humans are diphyodont, producing two sets of teeth: primary (milk) and permanent, which replace the first set.
3) Single Correct: Heterodont teeth include all except:
(A) Incisors
(B) Canines
(C) Molars
(D) All identical in shape
Explanation:
Answer is (D). Heterodont dentition consists of different types of teeth (incisors, canines, premolars, molars). Option D describes homodont dentition where teeth are all similar.
4) Assertion-Reason:
Assertion: Thecodont teeth are seen in humans.
Reason: They are set in sockets of jawbone.
(A) Both true, Reason correct
(B) Both true, Reason incorrect
(C) Assertion true, Reason false
(D) Both false
Explanation:
Answer is (A). Thecodont teeth are characteristic of mammals, including humans, and are set firmly in sockets of jawbone, ensuring strong anchorage for mastication.
5) Single Correct: Monophyodont condition is observed in:
(A) Humans
(B) Sharks
(C) Reptiles
(D) Rabbits
Explanation:
Answer is (B). Sharks are monophyodont, having a single set of continuously replaced teeth, unlike humans who are diphyodont.
6) Single Correct: Homodont dentition is characteristic of:
(A) Humans
(B) Crocodiles
(C) Dolphins
(D) Birds
Explanation:
Answer is (C). Dolphins have homodont teeth, all similar in shape and function, unlike humans who are heterodont.
7) Matching Type:
Column I | Column II
a. Thecodont | i. Teeth in sockets
b. Diphyodont | ii. Two sets of teeth
c. Heterodont | iii. Different types of teeth
(A) a-i, b-ii, c-iii
(B) a-ii, b-i, c-iii
(C) a-i, b-iii, c-ii
(D) a-iii, b-i, c-ii
Explanation:
Answer is (A). Thecodont teeth are set in sockets (a-i), diphyodont condition has two sets of teeth (b-ii), and heterodont dentition consists of different types (c-iii).
8) Fill in the Blank:
Humans are ______ because they have incisors, canines, premolars, and molars.
(A) Homodont
(B) Heterodont
(C) Monophyodont
(D) Polyphyodont
Explanation:
Answer is (B). Humans are heterodont with different types of teeth performing varied functions such as cutting, tearing, and grinding.
9) Choose the correct statements:
(i) Humans are diphyodont.
(ii) Human teeth are pleurodont.
(iii) Heterodont dentition allows varied functions.
(A) i and iii only
(B) i and ii only
(C) ii and iii only
(D) i, ii, iii
Explanation:
Answer is (A). Humans are diphyodont (i), heterodont (iii), but not pleurodont (ii), which is seen in reptiles.
10) Clinical-type: Loss of which type of teeth affects tearing food primarily in humans?
(A) Incisors
(B) Canines
(C) Molars
(D) Premolars
Explanation:
Answer is (B). Canines are pointed heterodont teeth specialized for tearing food; loss of canines impairs biting efficiency.
Subtopic: Gastric Cells and Hematopoiesis
Keyword Definitions:
• Parietal cells: Gastric cells that secrete hydrochloric acid and intrinsic factor.
• Chief cells: Gastric cells that secrete pepsinogen and gastric lipase.
• Goblet cells: Mucus-secreting epithelial cells lining the intestine.
• Mucous cells: Gastric cells producing protective mucus layer.
• Erythropoiesis: Process of red blood cell formation in bone marrow.
• Intrinsic factor: Glycoprotein secreted by parietal cells necessary for vitamin B12 absorption.
Lead Question - 2018
Which of the following gastric cells indirectly help in erythropoiesis :
(A) Parietal cells
(B) Chief cells
(C) Goblet cells
(D) Mucous cells
Explanation:
Answer is (A). Parietal cells secrete intrinsic factor, which is essential for the absorption of vitamin B12 in the ileum. Vitamin B12 is a critical cofactor for erythropoiesis in bone marrow. Other gastric cells like chief, goblet, and mucous cells do not contribute to red blood cell formation.
Guessed Questions for NEET UG:
1) Single Correct: The main function of intrinsic factor secreted by parietal cells is:
(A) Digest proteins
(B) Absorb vitamin B12
(C) Neutralize acid
(D) Secrete mucus
Explanation:
Answer is (B). Intrinsic factor binds to vitamin B12 and facilitates its absorption in the ileum, which is essential for erythropoiesis. Without intrinsic factor, B12 deficiency can lead to pernicious anemia.
2) Single Correct: Gastric chief cells secrete:
(A) Hydrochloric acid
(B) Pepsinogen
(C) Intrinsic factor
(D) Mucus
Explanation:
Answer is (B). Chief cells produce pepsinogen, an inactive enzyme precursor converted to pepsin by gastric acid, aiding protein digestion. They do not play a direct role in erythropoiesis.
3) Single Correct: Which vitamin deficiency is associated with impaired erythropoiesis due to lack of intrinsic factor?
(A) Vitamin C
(B) Vitamin B12
(C) Vitamin D
(D) Vitamin K
Explanation:
Answer is (B). Vitamin B12 absorption depends on intrinsic factor from parietal cells. Deficiency leads to megaloblastic anemia due to impaired DNA synthesis in erythroid precursors.
4) Assertion-Reason:
Assertion: Parietal cells contribute indirectly to erythropoiesis.
Reason: They secrete pepsinogen required for hemoglobin synthesis.
(A) Both true, Reason correct
(B) Both true, Reason incorrect
(C) Assertion true, Reason false
(D) Both false
Explanation:
Answer is (C). The assertion is correct as parietal cells support erythropoiesis via intrinsic factor. The reason is false because pepsinogen secretion by chief cells is unrelated to hemoglobin synthesis.
5) Clinical-type: Pernicious anemia results from deficiency of:
(A) Intrinsic factor
(B) Hydrochloric acid
(C) Pepsinogen
(D) Mucus
Explanation:
Answer is (A). Pernicious anemia arises when intrinsic factor from parietal cells is deficient, impairing vitamin B12 absorption. This leads to defective erythropoiesis and megaloblastic anemia, highlighting the clinical relevance of parietal cells.
6) Single Correct: Goblet cells in the gastrointestinal tract primarily secrete:
(A) Hydrochloric acid
(B) Pepsin
(C) Mucus
(D) Intrinsic factor
Explanation:
Answer is (C). Goblet cells secrete mucus to protect and lubricate the intestinal lining. They do not contribute to erythropoiesis.
7) Matching Type:
Column I | Column II
a. Parietal cells | i. Intrinsic factor
b. Chief cells | ii. Pepsinogen
c. Goblet cells | iii. Mucus
d. Mucous cells | iv. Protective layer
(A) a-i, b-ii, c-iii, d-iv
(B) a-ii, b-i, c-iv, d-iii
(C) a-iii, b-iv, c-i, d-ii
(D) a-i, b-iii, c-ii, d-iv
Explanation:
Answer is (A). Parietal cells produce intrinsic factor (a-i), chief cells secrete pepsinogen (b-ii), goblet cells secrete mucus (c-iii), and mucous cells provide protective mucus layer (d-iv).
8) Fill in the Blank:
Vitamin B12 absorption requires _______ secreted by parietal cells.
(A) Intrinsic factor
(B) Pepsinogen
(C) Hydrochloric acid
(D) Mucus
Explanation:
Answer is (A). Intrinsic factor, secreted by parietal cells, binds vitamin B12 and ensures its absorption in the ileum, which is necessary for proper erythropoiesis.
9) Choose the correct statements:
(i) Parietal cells secrete hydrochloric acid.
(ii) Intrinsic factor is required for red blood cell production.
(iii) Chief cells secrete intrinsic factor.
(A) i and ii only
(B) ii and iii only
(C) i and iii only
(D) i, ii, iii
Explanation:
Answer is (A). Statements i and ii are correct: parietal cells secrete HCl and intrinsic factor, which is essential for vitamin B12 absorption and erythropoiesis. Statement iii is false; intrinsic factor is not secreted by chief cells.
10) Clinical-type: Deficiency of intrinsic factor leads to which type of anemia?
(A) Iron-deficiency anemia
(B) Pernicious anemia
(C) Hemolytic anemia
(D) Aplastic anemia
Explanation:
Answer is (B). Pernicious anemia occurs due to lack of intrinsic factor from parietal cells, causing vitamin B12 deficiency. This impairs DNA synthesis in erythroid precursors, resulting in megaloblastic anemia and clinical manifestations like fatigue and pallor.
Topic: Digestion and Absorption
Subtopic: Crypts of Lieberkuhn and Secretory Cells
Keyword Definitions:
• Crypts of Lieberkuhn – Glandular invaginations in small intestine secreting digestive juices and antimicrobial substances.
• Paneth Cells – Specialized cells in crypts secreting lysozyme with antibacterial action.
• Kupffer Cells – Phagocytic liver cells removing toxins and pathogens.
• Argentaffin Cells – Enteroendocrine cells secreting serotonin and hormones.
• Zymogen Cells – Cells secreting inactive digestive enzyme precursors.
• Lysozyme – Enzyme breaking bacterial cell wall peptidoglycan.
• Antibacterial Action – Protection against intestinal pathogens.
• Enterocytes – Absorptive cells of intestine aiding nutrient uptake.
• Goblet Cells – Cells secreting mucus to protect intestinal lining.
• Clinical Gastroenterology – Branch dealing with digestive system diseases.
Lead Question – 2017:
Which cells of ‘Crypts of Lieberkuhn’ Secrete antibacterial lysozyme:
(A) Kupffer cells
(B) Argentaffin cells
(C) Paneth cells
(D) Zymogen cells
Explanation:
Correct answer is C (Paneth cells). Paneth cells, located at the base of crypts of Lieberkuhn, secrete lysozyme, an enzyme with antibacterial properties. This secretion protects intestinal mucosa against harmful microbes and maintains gut immunity, essential for healthy digestion and preventing infections. (Answer: C)
1) Single Correct Answer MCQ:
Which cells in intestine secrete mucus to protect lining?
(A) Goblet cells
(B) Paneth cells
(C) Kupffer cells
(D) Chief cells
Explanation:
Goblet cells in intestinal epithelium secrete mucus. This forms a protective barrier against digestive enzymes and pathogens, maintaining smooth passage of food and protection from mechanical damage. (Answer: A)
2) Single Correct Answer MCQ:
Which enzyme secreted by Paneth cells helps destroy bacteria?
(A) Trypsin
(B) Pepsin
(C) Lysozyme
(D) Lipase
Explanation:
Lysozyme is secreted by Paneth cells. It degrades bacterial cell walls, preventing infection and maintaining intestinal flora balance. (Answer: C)
3) Single Correct Answer MCQ:
Kupffer cells, unlike Paneth cells, are present in:
(A) Pancreas
(B) Liver
(C) Kidney
(D) Lungs
Explanation:
Kupffer cells are specialized macrophages in liver sinusoids, responsible for destroying pathogens, toxins, and worn-out RBCs. They are unrelated to intestinal Paneth cells. (Answer: B)
4) Single Correct Answer MCQ:
In Crypts of Lieberkuhn, which cells secrete digestive enzyme precursors?
(A) Paneth cells
(B) Zymogen cells
(C) Argentaffin cells
(D) Goblet cells
Explanation:
Zymogen cells secrete inactive digestive enzyme precursors that become active in intestine to aid digestion. This prevents autodigestion of mucosa. (Answer: B)
5) Single Correct Answer MCQ:
Which of the following is NOT secreted by intestinal glands?
(A) Lysozyme
(B) Mucus
(C) Pepsin
(D) Enterokinase
Explanation:
Pepsin is secreted by gastric glands, not intestinal glands. Crypts of Lieberkuhn secrete lysozyme, mucus, and enterokinase among other enzymes. (Answer: C)
6) Single Correct Answer MCQ:
A child with recurrent gut infections likely has defective:
(A) Kupffer cells
(B) Paneth cells
(C) Goblet cells
(D) Chief cells
Explanation:
Defective Paneth cells reduce lysozyme secretion, weakening antibacterial defense in intestine. This predisposes children to frequent gut infections. (Answer: B)
7) Assertion-Reason MCQ:
Assertion (A): Paneth cells play a role in intestinal immunity.
Reason (R): They secrete lysozyme that destroys bacterial walls.
(A) Both A and R true, R explains A
(B) Both A and R true, R does not explain A
(C) A true, R false
(D) A false, R true
Explanation:
Both assertion and reason are true. Paneth cells support intestinal immunity by secreting lysozyme, which lyses bacteria. Reason correctly explains assertion. (Answer: A)
8) Matching Type MCQ:
Match the cells with their functions:
1. Paneth cells – (i) Lysozyme secretion
2. Goblet cells – (ii) Mucus secretion
3. Argentaffin cells – (iii) Hormone release
Options:
(A) 1-i, 2-ii, 3-iii
(B) 1-iii, 2-i, 3-ii
(C) 1-ii, 2-iii, 3-i
(D) 1-i, 2-iii, 3-ii
Explanation:
Correct match is 1-i (Paneth cells – Lysozyme), 2-ii (Goblet cells – Mucus), 3-iii (Argentaffin – Hormones). (Answer: A)
9) Fill in the Blanks MCQ:
The specialized cells of crypts secreting antibacterial enzyme are called __________.
(A) Kupffer cells
(B) Paneth cells
(C) Goblet cells
(D) Chief cells
Explanation:
Paneth cells secrete lysozyme, an antibacterial enzyme, protecting intestine from microbial invasion. (Answer: B)
10) Choose the correct statements MCQ:
1. Paneth cells secrete lysozyme.
2. Kupffer cells are liver macrophages.
3. Goblet cells produce hormones.
4. Argentaffin cells secrete serotonin.
Options:
(A) 1, 2, 4
(B) 2, 3
(C) 1, 3
(D) 1, 4
Explanation:
Correct statements are 1, 2, and 4. Paneth cells produce lysozyme, Kupffer cells are macrophages in liver, and Argentaffin cells secrete serotonin. Goblet cells secrete mucus, not hormones. (Answer: A)
Subtopic: Hepatic Portal System
Keyword Definitions:
• Hepatic Portal Vein – Vein carrying nutrient-rich blood from gastrointestinal organs to liver.
• Liver – Organ responsible for metabolism, detoxification, and bile secretion.
• Intestine – Absorptive organ where digested nutrients enter blood.
• Stomach – Organ of protein digestion and food storage.
• Kidneys – Organs of excretion and osmoregulation.
• Detoxification – Process of neutralizing harmful substances.
• Cirrhosis – Chronic liver disease with fibrosis.
• Portal Hypertension – Increased blood pressure in hepatic portal circulation.
• Hepatocytes – Functional liver cells performing metabolism.
• Bile – Secretion aiding fat emulsification and absorption.
• Clinical Hepatology – Study of liver disorders and treatment.
Lead Question – 2017:
The hepatic portal vein drains blood to liver from:
(A) Intestine
(B) Heart
(C) Stomach
(D) Kidneys
Explanation:
Correct answer is A (Intestine). The hepatic portal vein carries blood rich in absorbed nutrients from small intestine, stomach, pancreas, and spleen to the liver. This blood undergoes detoxification and nutrient metabolism before entering systemic circulation, ensuring toxins do not reach the body directly. (Answer: A)
1) Single Correct Answer MCQ:
Which organ receives the first supply of absorbed nutrients from the intestine?
(A) Heart
(B) Liver
(C) Kidney
(D) Lungs
Explanation:
The liver is the first organ to receive absorbed nutrients via hepatic portal circulation. This allows nutrient storage, detoxification, and regulation of blood sugar before nutrients enter systemic circulation. (Answer: B)
2) Single Correct Answer MCQ:
Which blood vessel directly carries absorbed sugars and amino acids from intestine?
(A) Hepatic artery
(B) Hepatic portal vein
(C) Pulmonary vein
(D) Renal vein
Explanation:
Hepatic portal vein directly carries glucose, amino acids, and other absorbed nutrients from intestine to liver for processing, ensuring toxins are filtered before reaching systemic blood. (Answer: B)
3) Single Correct Answer MCQ:
Which of the following does not drain into hepatic portal circulation?
(A) Pancreas
(B) Spleen
(C) Kidneys
(D) Intestine
Explanation:
Kidneys do not drain into hepatic portal system. They directly release blood into systemic circulation via renal veins, while pancreas, spleen, and intestine drain into portal vein. (Answer: C)
4) Single Correct Answer MCQ:
A patient with liver cirrhosis develops enlarged veins in esophagus. This condition is due to:
(A) Portal Hypertension
(B) Anemia
(C) Hypoglycemia
(D) Thrombosis
Explanation:
Portal Hypertension occurs in cirrhosis, causing increased venous pressure. It leads to varices in esophagus and stomach, risk of bleeding, and ascites. (Answer: A)
5) Single Correct Answer MCQ:
Which type of blood does hepatic portal vein carry?
(A) Oxygen-rich
(B) Carbon dioxide-rich
(C) Nutrient-rich
(D) Deoxygenated only
Explanation:
Hepatic portal vein carries nutrient-rich blood, mainly glucose, amino acids, and vitamins from digestive organs. Although oxygen content is lower, its main role is nutrient transport to liver. (Answer: C)
6) Single Correct Answer MCQ:
Which vessel supplies oxygenated blood to the liver?
(A) Hepatic portal vein
(B) Hepatic artery
(C) Hepatic vein
(D) Inferior vena cava
Explanation:
Hepatic artery supplies oxygenated blood to the liver, while portal vein carries nutrient-rich blood. Both mix in sinusoids to nourish hepatocytes. (Answer: B)
7) Assertion-Reason MCQ:
Assertion (A): Hepatic portal vein ensures detoxification of absorbed substances.
Reason (R): Blood from intestine directly enters systemic circulation without liver involvement.
(A) Both A and R true, R explains A
(B) Both A and R true, R does not explain A
(C) A true, R false
(D) A false, R true
Explanation:
Assertion is true because hepatic portal vein ensures detoxification. Reason is false since intestinal blood first passes through liver before systemic circulation. (Answer: C)
8) Matching Type MCQ:
Match the structures with blood flow:
1. Intestine – (i) Nutrient absorption
2. Liver – (ii) Detoxification
3. Hepatic vein – (iii) Carries blood to inferior vena cava
Options:
(A) 1-i, 2-ii, 3-iii
(B) 1-ii, 2-iii, 3-i
(C) 1-iii, 2-i, 3-ii
(D) 1-i, 2-iii, 3-ii
Explanation:
Correct match is 1-i (intestine for absorption), 2-ii (liver for detoxification), 3-iii (hepatic vein to inferior vena cava). (Answer: A)
9) Fill in the Blanks MCQ:
The blood vessel carrying nutrient-rich blood from intestine to liver is called __________.
(A) Hepatic artery
(B) Hepatic vein
(C) Hepatic portal vein
(D) Inferior vena cava
Explanation:
The correct answer is Hepatic portal vein. It is a unique vessel connecting digestive organs to liver for detoxification and nutrient metabolism. (Answer: C)
10) Choose the correct statements MCQ:
1. Hepatic portal vein connects intestine and liver.
2. It carries oxygenated blood.
3. Liver receives blood from two sources.
4. Kidneys drain directly into hepatic portal vein.
Options:
(A) 1, 3
(B) 2, 4
(C) 1, 2
(D) 3, 4
Explanation:
Correct statements are 1 and 3. Hepatic portal vein connects intestine to liver. Liver receives blood from portal vein and hepatic artery. It does not carry highly oxygenated blood, and kidneys do not drain into it. (Answer: A)
Topic: Digestive System
Subtopic: Dentition in Humans
Keyword Definitions:
• Dentition – Arrangement and development of teeth.
• Deciduous Teeth – Primary or milk teeth appearing in children.
• Permanent Teeth – Secondary teeth replacing milk teeth.
• Incisors – Front teeth used for cutting food.
• Canines – Pointed teeth for tearing food.
• Molars – Large teeth at the back used for grinding.
• Premolars – Transitional teeth between canines and molars, absent in milk teeth.
• Dental Formula – Shorthand representation of teeth arrangement.
• Eruption – Process of teeth breaking through gums.
• Mixed Dentition – Phase where milk and permanent teeth coexist.
• Oral Health – Condition of teeth and gums affecting digestion.
Lead Question – 2017:
A baby aged two years is admitted to play school and passes through a dental check-up. The dentist observed that the boy had twenty teeth. Which teeth were absent:
(A) Molars
(B) Incisors
(C) Canines
(D) Pre-molars
Explanation:
Correct answer is D (Pre-molars). A two-year-old child has 20 deciduous teeth, consisting of incisors, canines, and molars but lacking premolars. Permanent dentition later includes premolars, which replace milk molars. Their absence in milk dentition helps differentiate between deciduous and adult dental formula. (Answer: D)
1) Single Correct Answer MCQ:
How many permanent teeth are present in a normal adult human?
(A) 28
(B) 30
(C) 32
(D) 34
Explanation:
An adult human typically has 32 permanent teeth with dental formula 2123/2123. This includes incisors, canines, premolars, and molars. Third molars (wisdom teeth) may erupt variably. (Answer: C)
2) Single Correct Answer MCQ:
What is the dental formula of deciduous teeth in humans?
(A) 2123/2123
(B) 2102/2102
(C) 2101/2101
(D) 2120/2120
Explanation:
The deciduous dental formula in humans is 2102/2102, totaling 20 teeth, including incisors, canines, and molars, but no premolars. (Answer: B)
3) Single Correct Answer MCQ:
Which teeth erupt first in infants?
(A) Molars
(B) Canines
(C) Incisors
(D) Premolars
Explanation:
Lower central incisors are usually the first to erupt in infants at about 6–8 months of age, initiating the sequence of deciduous dentition. (Answer: C)
4) Single Correct Answer MCQ:
Which type of teeth are also called "cuspids"?
(A) Molars
(B) Premolars
(C) Incisors
(D) Canines
Explanation:
Canines are also called cuspids due to their pointed structure used for tearing. They play an important role in occlusion and maintaining dental arch stability. (Answer: D)
5) Single Correct Answer MCQ:
At what age does the first permanent molar generally erupt?
(A) 3 years
(B) 6 years
(C) 12 years
(D) 18 years
Explanation:
The first permanent molar erupts around the age of 6 years, marking the beginning of mixed dentition phase where both milk and permanent teeth coexist. (Answer: B)
6) Single Correct Answer MCQ:
Which teeth are commonly affected in "wisdom tooth" problems?
(A) First molars
(B) Second molars
(C) Third molars
(D) Premolars
Explanation:
Third molars, also called wisdom teeth, are the last to erupt (17–25 years). They often cause impaction due to lack of space, leading to pain and infections. (Answer: C)
7) Assertion-Reason MCQ:
Assertion (A): Premolars are absent in milk dentition.
Reason (R): They are replaced by permanent premolars later in life.
(A) Both A and R true, R explains A
(B) Both A and R true, R does not explain A
(C) A true, R false
(D) A false, R true
Explanation:
Premolars are absent in milk dentition, and permanent premolars later replace primary molars. Thus, both assertion and reason are true, and reason correctly explains assertion. (Answer: A)
8) Matching Type MCQ:
Match teeth types with function:
1. Incisors – (i) Grinding
2. Canines – (ii) Cutting
3. Molars – (iii) Tearing
Options:
(A) 1-ii, 2-iii, 3-i
(B) 1-i, 2-ii, 3-iii
(C) 1-iii, 2-i, 3-ii
(D) 1-ii, 2-i, 3-iii
Explanation:
Incisors cut (1-ii), canines tear (2-iii), molars grind (3-i). Correct matching is 1-ii, 2-iii, 3-i. (Answer: A)
9) Fill in the Blanks MCQ:
________ teeth are absent in deciduous dentition of humans.
(A) Molars
(B) Canines
(C) Premolars
(D) Incisors
Explanation:
Premolars are absent in milk dentition, appearing only in permanent dentition. This makes the deciduous dental formula different from adult formula. (Answer: C)
10) Choose the correct statements MCQ:
1. Milk teeth are 20 in number.
2. Premolars are present in milk dentition.
3. Permanent dentition includes 32 teeth.
4. Canines are absent in children.
Options:
(A) 1, 3
(B) 2, 4
(C) 1, 2, 3
(D) 1, 4
Explanation:
Statements 1 and 3 are correct: milk teeth are 20, permanent dentition includes 32. Premolars are absent in milk teeth, and canines are present in children. Correct option: (Answer: A)
Subtopic: Pancreatic Secretions and Enzyme Functions
Keyword Definitions:
• Pancreatic juice – Alkaline fluid secreted by pancreas containing digestive enzymes.
• Lipase – Enzyme that hydrolyzes triglycerides into fatty acids and glycerol.
• Amylase – Enzyme that breaks down starch into maltose.
• Trypsinogen – Inactive precursor of trypsin, a protease that digests proteins.
• Procarboxypeptidase – Inactive precursor of carboxypeptidase, which cleaves terminal amino acids from peptides.
• Peptidase – Enzyme breaking down peptides into amino acids.
• Clinical relevance – Understanding pancreatic enzymes is essential in diagnosing pancreatitis, cystic fibrosis, and digestive disorders.
Lead Question – 2017:
Which of the following options best represent enzyme composition of pancreatic juice ?
(A) Lipase, amylase, trypsinogen, procarboxypeptidase
(B) Amylase, peptidase, trypsinogen, rennin
(C) Amylase, pepsin, trypsinogen, maltase
(D) Peptidase, amylase, pepsin, rennin
Explanation:
Pancreatic juice contains lipase, amylase, trypsinogen, and procarboxypeptidase. Lipase digests fats, amylase digests starch, trypsinogen activates to trypsin to digest proteins, and procarboxypeptidase converts to carboxypeptidase for further protein digestion. Pepsin and rennin are gastric enzymes, not pancreatic. (Answer: A)
1) Which pancreatic enzyme hydrolyzes starch?
(A) Lipase
(B) Amylase
(C) Trypsin
(D) Carboxypeptidase
Explanation:
Amylase in pancreatic juice catalyzes starch breakdown into maltose. Lipase digests fats, trypsin hydrolyzes proteins, and carboxypeptidase cleaves terminal amino acids. Proper amylase function ensures carbohydrate digestion and absorption in the small intestine. (Answer: B)
2) Trypsinogen is:
(A) Active enzyme
(B) Zymogen
(C) Hormone
(D) Transport protein
Explanation:
Trypsinogen is an inactive zymogen secreted by the pancreas. It is activated in the small intestine to trypsin, which digests proteins. This prevents autodigestion of pancreatic tissue and is a critical safety mechanism in digestive physiology. (Answer: B)
3) Clinical case: Deficiency of pancreatic lipase leads to:
(A) Steatorrhea
(B) Hyperglycemia
(C) Proteinuria
(D) Vomiting
Explanation:
Pancreatic lipase deficiency results in fat malabsorption, producing fatty stools (steatorrhea), weight loss, and nutrient deficiencies. Lipase is crucial for triglyceride hydrolysis. Amylase and proteases deficiency would affect carbohydrates and proteins, respectively. Early detection prevents malnutrition and digestive complications. (Answer: A)
4) Which enzyme is responsible for cleaving terminal amino acids from peptides?
(A) Lipase
(B) Carboxypeptidase
(C) Amylase
(D) Pepsin
Explanation:
Carboxypeptidase, derived from procarboxypeptidase, hydrolyzes terminal amino acids from peptide chains. Trypsin cleaves internal peptide bonds. Lipase digests fats, and pepsin (gastric) acts on proteins in the stomach. Pancreatic enzyme balance is vital for protein digestion. (Answer: B)
5) Which pancreatic enzyme acts on fats?
(A) Amylase
(B) Lipase
(C) Trypsin
(D) Maltase
Explanation:
Lipase hydrolyzes triglycerides into glycerol and fatty acids. Proper fat digestion requires bile salts and pancreatic lipase. Deficiency leads to malabsorption, steatorrhea, and vitamin deficiencies. Amylase digests starch, trypsin digests proteins, and maltase digests maltose. (Answer: B)
6) Zymogen activation occurs in:
(A) Stomach
(B) Small intestine
(C) Liver
(D) Pancreas
Explanation:
Pancreatic zymogens such as trypsinogen and procarboxypeptidase are activated in the small intestine by enterokinase and trypsin. This prevents autodigestion of pancreas. Proper activation ensures efficient protein digestion in duodenum. (Answer: B)
7) Assertion-Reason type:
Assertion (A): Pancreatic juice contains inactive proteases.
Reason (R): Inactive forms prevent self-digestion of pancreatic tissue.
(A) Both A and R are true, and R is the correct explanation of A
(B) Both A and R are true, but R is not the correct explanation
(C) A is true, R is false
(D) A is false, R is true
Explanation:
Both A and R are true, and R explains A. Trypsinogen and procarboxypeptidase are inactive in the pancreas, preventing autodigestion. Activation occurs in the small intestine, ensuring safe protein digestion. Clinical relevance includes pancreatitis if activation occurs prematurely. (Answer: A)
8) Matching type:
Match enzyme with substrate:
(A) Amylase – (i) Starch
(B) Lipase – (ii) Triglycerides
(C) Trypsin – (iii) Proteins
(D) Carboxypeptidase – (iv) Terminal amino acids
Options:
(A) A-i, B-ii, C-iii, D-iv
(B) A-ii, B-i, C-iv, D-iii
(C) A-iii, B-iv, C-ii, D-i
(D) A-i, B-iii, C-ii, D-iv
Explanation:
Correct matches: Amylase – starch, Lipase – triglycerides, Trypsin – proteins, Carboxypeptidase – terminal amino acids. Understanding enzyme-substrate specificity is critical in clinical diagnosis of pancreatic disorders and digestion-related diseases. (Answer: A)
9) Fill in the blanks:
Inactive protein-digesting enzyme secreted by pancreas is ______.
(A) Trypsinogen
(B) Amylase
(C) Lipase
(D) Maltase
Explanation:
Trypsinogen is the inactive protease secreted by pancreas. It is converted to trypsin in the duodenum. This prevents pancreatic autodigestion and ensures safe protein digestion. Malfunction can lead to pancreatitis and digestive issues. (Answer: A)
10) Choose the correct statements:
1. Pancreatic juice contains lipase and amylase.
2. Trypsinogen and procarboxypeptidase are inactive zymogens.
3. Pepsin is a pancreatic enzyme.
4. Lipase digests fats in the small intestine.
(A) 1, 2, 4 only
(B) 2, 3, 4 only
(C) 1, 3, 4 only
(D) All are correct
Explanation:
Statements 1, 2, and 4 are correct. Statement 3 is false because pepsin is a gastric enzyme, not pancreatic. Correct understanding of enzyme composition aids in diagnosing pancreatic disorders and optimizing digestive health. (Answer: A)
Chapter: Human Physiology
Topic: Digestion and Absorption
Subtopic: Hormonal Control of Pancreatic Secretion
Pancreatic juice: Digestive secretion containing enzymes like trypsin, lipase, and amylase.
Bicarbonate: Alkaline component secreted to neutralize stomach acid in the duodenum.
Cholecystokinin (CCK): Hormone stimulating pancreatic enzyme secretion and gallbladder contraction.
Secretin: Hormone stimulating bicarbonate secretion from the pancreas.
Insulin: Hormone regulating glucose uptake and metabolism.
Glucagon: Hormone raising blood glucose by stimulating glycogen breakdown.
Gastrin: Hormone stimulating gastric acid secretion.
Epinephrine: Stress hormone increasing blood glucose and heart rate.
Angiotensin: Hormone involved in blood pressure regulation.
Duodenum: First part of the small intestine where pancreatic juice is released.
Lead Question - 2016 (Phase 2): Which hormones do stimulate the production of pancreatic juice and bicarbonate?
Options:
1) Insulin and glucagon
2) Angiotensin and epinephrine
3) Gastrin and insulin
4) Cholecystokinin and secretin
Answer & Explanation: The correct answer is 4) Cholecystokinin and secretin. CCK stimulates pancreatic enzyme secretion, while Secretin induces bicarbonate secretion. Together they regulate digestion by neutralizing acidic chyme and providing enzymes. This coordination ensures effective digestion and absorption of nutrients in the small intestine after gastric emptying.
Guessed NEET UG MCQs:
1. Which hormone mainly stimulates bicarbonate secretion from the pancreas?
a) Gastrin
b) Secretin
c) Insulin
d) Epinephrine
Answer & Explanation: The correct answer is b) Secretin. Secretin is secreted by duodenal mucosa in response to acidic chyme. It stimulates pancreatic duct cells to release bicarbonate-rich fluid. This neutralizes stomach acid, creating an optimal pH for pancreatic enzymes to function efficiently in the small intestine.
2. Which hormone stimulates secretion of pancreatic enzymes?
a) Secretin
b) Cholecystokinin
c) Glucagon
d) Angiotensin
Answer & Explanation: The correct answer is b) Cholecystokinin. CCK, secreted from the duodenal mucosa, promotes secretion of enzyme-rich pancreatic juice. It also causes gallbladder contraction, releasing bile. This dual role helps in emulsifying fats and enzymatic breakdown of food, aiding efficient digestion in the small intestine.
3. A patient with pancreatic duct obstruction will most likely suffer from:
a) Hyperglycemia
b) Impaired digestion
c) Increased bile secretion
d) Reduced gastric emptying
Answer & Explanation: The correct answer is b) Impaired digestion. Obstruction of the pancreatic duct blocks enzyme and bicarbonate secretion. Without these, proteins, fats, and carbohydrates remain undigested. This leads to malabsorption, diarrhea, and steatorrhea. Clinically, pancreatic insufficiency is associated with poor nutrient absorption and weight loss in affected patients.
4. Which of the following does NOT stimulate pancreatic juice secretion?
a) Secretin
b) Cholecystokinin
c) Gastrin
d) Epinephrine
Answer & Explanation: The correct answer is d) Epinephrine. Unlike CCK, secretin, and gastrin, epinephrine is a stress hormone and does not regulate pancreatic secretion. Instead, it diverts blood flow away from the gastrointestinal tract during stress, reducing digestion rather than promoting enzyme or bicarbonate secretion.
5. Assertion-Reason:
Assertion (A): Secretin stimulates bicarbonate secretion.
Reason (R): Bicarbonate neutralizes gastric acid in duodenum.
a) Both A and R are true, R is correct explanation of A
b) Both A and R are true, R is not correct explanation of A
c) A is true, R is false
d) A is false, R is true
Answer & Explanation: The correct answer is a) Both A and R are true, R is correct explanation of A. Secretin activates pancreatic duct cells to release bicarbonate. This alkaline secretion neutralizes stomach acid, ensuring the duodenal environment is suitable for pancreatic enzymes to act effectively in digestion.
6. Match the hormones with their functions:
Column I: a) Secretin b) CCK c) Insulin d) Gastrin
Column II: i) Stimulates gastric acid secretion ii) Stimulates pancreatic enzymes iii) Regulates glucose uptake iv) Stimulates bicarbonate secretion
Options:
1) a-iv, b-ii, c-iii, d-i
2) a-iii, b-ii, c-i, d-iv
3) a-ii, b-iv, c-i, d-iii
4) a-i, b-iii, c-iv, d-ii
Answer & Explanation: The correct answer is 1) a-iv, b-ii, c-iii, d-i. Secretin induces bicarbonate secretion, CCK stimulates pancreatic enzymes, Insulin regulates glucose uptake, and Gastrin promotes gastric acid secretion. Each hormone plays a specialized role in maintaining digestion, metabolism, and gastrointestinal physiology.
7. Fill in the blank: The hormone secreted in response to acidic chyme in the duodenum is ______.
a) Gastrin
b) Secretin
c) CCK
d) Insulin
Answer & Explanation: The correct answer is b) Secretin. Secretin is secreted by S cells of the duodenum when acidic chyme enters from the stomach. It signals the pancreas to secrete bicarbonate, neutralizing the acid. This protects the mucosa and enables enzymes to work in a neutral environment.
8. Choose the correct statements about CCK and Secretin:
a) CCK stimulates pancreatic enzyme secretion
b) Secretin stimulates bicarbonate secretion
c) CCK causes gallbladder contraction
d) Both inhibit gastric acid secretion
Options:
1) a, b, c
2) a, b
3) b, d
4) a, c, d
Answer & Explanation: The correct answer is 1) a, b, c. CCK promotes pancreatic enzymes and gallbladder contraction, Secretin induces bicarbonate secretion. Both modulate gastric emptying but do not directly inhibit gastric acid secretion. Their combined function is crucial for digestion and duodenal protection against acidity.
9. Clinical case: A patient with deficiency of secretin secretion will most likely present with:
a) Hyperacidity in duodenum
b) Gallstone formation
c) Increased bile production
d) Low blood glucose
Answer & Explanation: The correct answer is a) Hyperacidity in duodenum. Without Secretin, bicarbonate secretion is impaired, leading to unneutralized acid damaging the duodenal lining. Clinically this can cause duodenal ulcers, malabsorption, and abdominal pain. Treatment requires acid suppression and supportive therapy to restore digestive balance.
10. Which of the following hormones acts synergistically with CCK in pancreatic secretion?
a) Secretin
b) Gastrin
c) Insulin
d) Epinephrine
Answer & Explanation: The correct answer is a) Secretin. Secretin and CCK act together: secretin enhances bicarbonate secretion while CCK promotes enzyme secretion. Their synergy ensures digestion proceeds efficiently by neutralizing acid and releasing necessary enzymes, optimizing the breakdown and absorption of proteins, carbohydrates, and lipids in the intestine.
Chapter: Human Physiology
Topic: Digestive System
Subtopic: Accessory Organs and Ducts
Keyword Definitions:
Hepatopancreatic Duct: Also called the bile duct, it carries bile and pancreatic juice into the duodenum.
Duodenum: The first section of the small intestine where digestion continues with bile and enzymes.
Sphincter of Oddi: A muscular valve controlling the flow of digestive juices (bile and pancreatic juice) into the duodenum.
Semilunar Valve: Found in the heart, not related to digestive system.
Ileocecal Valve: Separates small intestine and large intestine, prevents backflow.
Pyloric Sphincter: Controls passage of chyme from stomach to duodenum.
2016 (Phase 1)
Lead Question: Which of the following guards the opening of hepatopancreatic duct into the duodenum:
(1) Semilunar valve
(2) Ileocaecal valve
(3) Pyloric sphincter
(4) Sphincter of Oddi
Answer & Explanation: The correct answer is (4). The Sphincter of Oddi is a muscular valve regulating the flow of bile and pancreatic juice into the duodenum from the hepatopancreatic duct. It prevents the backflow of duodenal contents into the duct and ensures controlled release of digestive enzymes crucial for digestion and absorption.
Single Correct Answer MCQ: The primary function of the pyloric sphincter is to:
(1) Allow bile into the stomach
(2) Control passage of chyme into the duodenum
(3) Connect small and large intestines
(4) Regulate bile and pancreatic juice secretion
Answer & Explanation: The correct answer is (2). The pyloric sphincter controls the release of partially digested food (chyme) from the stomach into the duodenum. It prevents reflux of intestinal contents and regulates the rate of gastric emptying, thus ensuring proper digestion and nutrient absorption in the small intestine.
Assertion-Reason MCQ:
Assertion (A): The hepatopancreatic duct is essential for digestion in the small intestine.
Reason (R): It carries bile and pancreatic juice into the duodenum aiding digestion of fats and carbohydrates.
(1) Both A and R are true, and R is correct explanation of A.
(2) Both A and R are true, but R is not correct explanation of A.
(3) A is true, but R is false.
(4) A is false, but R is true.
Answer & Explanation: The correct answer is (1). The hepatopancreatic duct conveys bile from the liver and gall bladder, and pancreatic juice from the pancreas, into the duodenum. These secretions are essential for emulsifying fats and providing enzymes for digestion of carbohydrates, proteins, and fats in the small intestine.
Matching Type MCQ: Match the valve/sphincter to its function:
A. Sphincter of Oddi 1. Controls chyme passage into duodenum
B. Ileocecal Valve 2. Regulates bile and pancreatic juice entry
C. Pyloric Sphincter 3. Prevents backflow from large intestine
D. Semilunar Valve 4. Found in heart, not digestive system
(1) A-2, B-3, C-1, D-4
(2) A-1, B-2, C-3, D-4
(3) A-3, B-1, C-2, D-4
(4) A-4, B-3, C-2, D-1
Answer & Explanation: The correct answer is (1). The Sphincter of Oddi regulates bile and pancreatic juice flow; the ileocecal valve prevents backflow from large to small intestine; the pyloric sphincter controls chyme movement; the semilunar valve is part of the heart's circulatory system.
Fill in the Blanks / Completion MCQ: The muscular valve that regulates the flow of bile and pancreatic juice into the duodenum is called ________.
(1) Pyloric sphincter
(2) Ileocecal valve
(3) Sphincter of Oddi
(4) Cardiac sphincter
Answer & Explanation: The correct answer is (3). The Sphincter of Oddi is a crucial structure that controls the flow of bile and pancreatic juice into the duodenum, thereby facilitating digestion of fats, proteins, and carbohydrates efficiently while preventing reflux of duodenal contents.
Choose the correct statements MCQ:
1. The Sphincter of Oddi controls bile entry into the duodenum.
2. Ileocecal valve is present between stomach and duodenum.
3. Pyloric sphincter regulates chyme passage.
4. Semilunar valves are involved in blood circulation.
(1) 1, 3, and 4 only
(2) 1 and 2 only
(3) 2 and 3 only
(4) 1, 2, and 3 only
Answer & Explanation: The correct answer is (1). The Sphincter of Oddi regulates bile and pancreatic juice release. The Pyloric sphincter controls chyme passage into the duodenum. Semilunar valves are heart structures, unrelated to digestion. The ileocecal valve connects the small intestine to large intestine, not stomach and duodenum.
Topic: Digestive System
Subtopic: Gastric Secretions and Functions
Keyword Definitions:
Gastric Acid: Digestive fluid composed mainly of hydrochloric acid (HCl) produced in the stomach.
Parietal Cells: Cells in the stomach lining responsible for secreting hydrochloric acid.
Gastrin: Hormone that stimulates secretion of gastric acid by parietal cells.
Peptic Cells: Also called chief cells, they secrete pepsinogen, which becomes pepsin in acidic pH.
Hydrochloric Acid: Strong acid in gastric juice aiding digestion and defense against pathogens.
2016 (Phase 1)
Lead Question: In the stomach, gastric acid is secreted by the:
(1) Gastrin secreting cells
(2) Parietal cells
(3) Peptic cells
(4) Acidic cells
Answer & Explanation: The correct answer is (2). Parietal cells, found in the gastric glands of the stomach lining, are responsible for secreting hydrochloric acid (HCl). This acid maintains an acidic environment necessary for pepsinogen activation, protein digestion, and killing harmful microbes entering with food.
Keyword Definitions:
Gastric Glands: Specialized glands in the stomach lining that secrete gastric juice components.
Single Correct Answer MCQ: The role of hydrochloric acid in the stomach includes:
(1) Neutralizing chyme
(2) Activating pepsinogen to pepsin
(3) Emulsifying fats
(4) Absorbing vitamins
Answer & Explanation: The correct answer is (2). Hydrochloric acid activates pepsinogen secreted by chief cells into pepsin, which digests proteins. This highly acidic environment also prevents microbial infections. Neutralization occurs in the intestine, while emulsification and vitamin absorption are functions of bile and intestinal cells.
Keyword Definitions:
Pepsin: Active enzyme that breaks down proteins into peptides.
Single Correct Answer MCQ (Clinical Type): Excessive gastric acid secretion may lead to:
(1) Peptic ulcers
(2) Constipation
(3) Diabetes
(4) Anemia
Answer & Explanation: The correct answer is (1). Excess hydrochloric acid secretion can damage the stomach lining, causing peptic ulcers. These painful sores are a clinical concern requiring medical treatment with acid inhibitors and protective agents. Proper regulation of acid secretion is essential for digestive health and preventing gastrointestinal disorders.
Keyword Definitions:
Peptic Ulcer: A sore in the stomach lining due to acid damage.
Single Correct Answer MCQ: Which hormone stimulates gastric acid secretion?
(1) Secretin
(2) Gastrin
(3) Cholecystokinin
(4) Insulin
Answer & Explanation: The correct answer is (2). Gastrin, secreted by G-cells in the stomach antrum, stimulates parietal cells to secrete hydrochloric acid. This hormone plays a crucial role in regulating gastric acid production in response to food intake, thereby aiding digestion and maintaining proper stomach pH.
Keyword Definitions:
G-cells: Gastrin-secreting cells located in the gastric mucosa.
Single Correct Answer MCQ: The pH of gastric acid in the stomach typically is:
(1) 7.4
(2) 1.5 – 3.5
(3) 5.5 – 6.5
(4) 8.0 – 9.0
Answer & Explanation: The correct answer is (2). The pH of gastric acid ranges from 1.5 to 3.5. This high acidity is essential for protein denaturation, pepsinogen activation, and killing pathogens. Maintaining this pH is vital for digestion and protection of the gastrointestinal tract.
Keyword Definitions:
pH: Measure of hydrogen ion concentration indicating acidity or alkalinity.
Assertion-Reason MCQ:
Assertion (A): Parietal cells secrete hydrochloric acid in the stomach.
Reason (R): Hydrochloric acid creates an acidic environment for digestion and pathogen defense.
(1) Both A and R are true, and R is correct explanation of A
(2) Both A and R are true, but R is not correct explanation of A
(3) A is true, but R is false
(4) A is false, but R is true
Answer & Explanation: The correct answer is (1). Parietal cells produce hydrochloric acid, which lowers stomach pH, aiding protein digestion and preventing microbial infections. This is a fundamental mechanism of digestion, ensuring breakdown of food and maintaining gastric hygiene.
Keyword Definitions:
Stomach pH: Typically acidic (1.5-3.5) due to HCl secretion by parietal cells.
Matching Type MCQ: Match the cell type with its function:
A. Parietal Cells 1. Secrete hydrochloric acid
B. G-cells 2. Secrete gastrin
C. Chief Cells 3. Secrete pepsinogen
(1) A-1, B-2, C-3
(2) A-2, B-3, C-1
(3) A-3, B-1, C-2
(4) A-1, B-3, C-2
Answer & Explanation: The correct answer is (1). Parietal cells secrete hydrochloric acid, G-cells produce gastrin to stimulate acid secretion, and chief cells secrete pepsinogen for protein digestion. This coordinated action ensures efficient breakdown of food and optimal conditions for nutrient absorption.
Keyword Definitions:
Chief Cells: Cells in gastric glands that produce pepsinogen, precursor to pepsin enzyme.
Fill in the Blanks / Completion MCQ: The cells responsible for secreting hydrochloric acid in the stomach are called __________.
(1) G-cells
(2) Parietal cells
(3) Chief cells
(4) Mucous cells
Answer & Explanation: The correct answer is (2). Parietal cells located in the gastric glands are specialized to secrete hydrochloric acid. This acid is crucial for creating an acidic environment in the stomach, which aids digestion, activates enzymes, and provides defense against ingested pathogens.
Keyword Definitions:
Mucous Cells: Cells producing mucus to protect the stomach lining from acid damage.
Choose the correct statements MCQ:
1. Gastric acid is secreted by parietal cells.
2. Gastrin stimulates gastric acid secretion.
3. Pepsinogen is activated by gastric acid.
4. Hydrochloric acid is secreted by chief cells.
(1) 1, 2, 3 only
(2) 1 and 4 only
(3) 2, 3, 4 only
(4) All statements are correct
Answer & Explanation: The correct answer is (1). Statements 1, 2, and 3 are correct. Parietal cells secrete gastric acid, gastrin stimulates acid secretion, and pepsinogen is activated by acid. However, hydrochloric acid is not secreted by chief cells, which produce pepsinogen instead, making statement 4 incorrect.