Try each question on your own first. Use the Show Answer button only after you have selected your option, then read the explanation and revise the related concept from your chapter notes.
Explanation: The adult human dental formula is 2123/2123, representing 2 incisors, 1 canine, 2 premolars, and 3 molars in each half of the upper and lower jaws.
2. Which cells of the gastric glands secrete hydrochloric acid (HCl) and intrinsic factor?
A. Oxyntic (Parietal) cells
B. Peptic (Chief) cells
C. Goblet cells
D. Mucous neck cells
Answer: A. Oxyntic (Parietal) cells
Explanation: Oxyntic or parietal cells secrete HCl and Castle's intrinsic factor, which is essential for the absorption of vitamin B12.
3. Pepsinogen is converted into active pepsin by the action of:
A. Hydrochloric acid (HCl)
B. Enterokinase
C. Trypsin
D. Bile salts
Answer: A. Hydrochloric acid (HCl)
Explanation: In the stomach, inactive pepsinogen is activated to active enzyme pepsin upon exposure to hydrochloric acid (HCl).
4. Which enzyme activates trypsinogen into active trypsin in the small intestine?
A. Enterokinase
B. Amylase
C. Lipase
D. Pepsin
Answer: A. Enterokinase
Explanation: Trypsinogen is activated by an enzyme enterokinase, secreted by the intestinal mucosa, into active trypsin.
5. Bile is produced in the liver and stored in the:
A. Gall bladder
B. Pancreas
C. Spleen
D. Duodenum
Answer: A. Gall bladder
Explanation: Bile is secreted by hepatic cells of the liver and stored and concentrated in a thin muscular sac called the gall bladder.
6. The common bile duct and pancreatic duct open together into the duodenum as the hepato-pancreatic duct, guarded by:
A. Sphincter of Oddi
B. Gastro-oesophageal sphincter
C. Pyloric sphincter
D. Ileo-caecal valve
Answer: A. Sphincter of Oddi
Explanation: The opening of the hepato-pancreatic duct into the duodenum is regulated by a muscle sphincter called the Sphincter of Oddi.
7. Small droplets of fat coated with protein that are transported into lacteals are called:
A. Chylomicrons
B. Micelles
C. Fatty acids
D. Glycerol
Answer: A. Chylomicrons
Explanation: Fatty acids and glycerol are re-formed into tiny protein-coated fat globules called chylomicrons, which are transported into the lymph vessels (lacteals).
8. Which of the following is a proteolytic enzyme found in gastric juice of infants that helps in digestion of milk proteins?
A. Rennin
B. Renin
C. Amylase
D. Ptyalin
Answer: A. Rennin
Explanation: Rennin is a proteolytic enzyme found in gastric juice of infants which helps in the digestion of milk proteins (casein).
9. The structural type of human dentition where teeth are embedded in sockets of jaw bones is known as:
A. Thecodont
B. Diphyodont
C. Heterodont
D. Homodont
Answer: A. Thecodont
Explanation: Each tooth is embedded in a socket of jaw bone. This type of tooth attachment is called thecodont.
10. Crypts of Lieberkühn are present in:
A. Small intestine
B. Stomach
C. Oesophagus
D. Large intestine
Answer: A. Small intestine
Explanation: Crypts of Lieberkühn are tubular glands located at the base of the villi in the mucosa of the small intestine.
11. Brunner's glands are characteristic features of which part of the alimentary canal?
A. Submucosa of duodenum
B. Mucosa of stomach
C. Submucosa of ileum
D. Mucosa of jejunum
Answer: A. Submucosa of duodenum
Explanation: Brunner's glands are submucosal glands located specifically in the duodenum of the small intestine.
12. Salivary amylase (ptyalin) converts starch into maltose at an optimum pH of:
A. 6.8
B. 1.8
C. 7.8
D. 8.5
Answer: A. 6.8
Explanation: Salivary amylase hydrolyses about 30% of starch into maltose in the oral cavity at an optimal pH of 6.8.
13. Which disorder of the digestive system involves yellowing of skin and eyes due to accumulation of bile pigments?
A. Jaundice
B. Vomiting
C. Diarrhoea
D. Constipation
Answer: A. Jaundice
Explanation: In jaundice, the liver is affected, leading to deposition of bile pigments that causes yellow skin and eyes.
14. Kwashiorkor and Marasmus are deficiency diseases resulting from:
A. Protein-Energy Malnutrition (PEM)
B. Vitamin deficiency
C. Mineral deficiency
D. Excess fat intake
Answer: A. Protein-Energy Malnutrition (PEM)
Explanation: Marasmus and Kwashiorkor are severe dietary deficiencies of proteins and calories (PEM) found in infants and children.
15. The outermost layer of the wall of the alimentary canal is known as:
A. Serosa
B. Muscularis
C. Submucosa
D. Mucosa
Answer: A. Serosa
Explanation: The wall of alimentary canal from oesophagus to rectum possesses four layers: Serosa (outermost), Muscularis, Submucosa, and Mucosa (innermost).
16. Intestinal juice secreted by the crypts and goblet cells is collectively termed as:
A. Succus entericus
B. Gastric juice
C. Pancreatic juice
D. Chyme
Answer: A. Succus entericus
Explanation: The secretions of the goblet cells along with secretions of mucosal brush border cells form the intestinal juice or succus entericus.
17. Which component of bile helps in the emulsification of fats?
A. Bile salts
B. Bile pigments
C. Cholesterol
D. Phospholipids
Answer: A. Bile salts
Explanation: Bile salts (like sodium glycocholate and taurocholate) break down large fat globules into tiny droplets (emulsification).
18. Semi-digested, acidic food moving from the stomach into the duodenum is called:
A. Chyme
B. Bolus
C. Chyle
D. Succus
Answer: A. Chyme
Explanation: Food thoroughly mixed with acidic gastric juice in the stomach by churning movements is called chyme.
19. Which structure prevents the entry of food into the glottis during swallowing?
A. Epiglottis
B. Hard palate
C. Soft palate
D. Frenulum
Answer: A. Epiglottis
Explanation: A cartilaginous flap called epiglottis prevents the entry of food into the glottis (opening of the windpipe) during deglutition.
20. Absorption of maximum nutrients occurs in which part of the alimentary canal?
A. Small intestine
B. Stomach
C. Large intestine
D. Mouth
Answer: A. Small intestine
Explanation: The small intestine (especially jejunum and ileum) is the principal organ for absorption of nutrients due to presence of villi and microvilli.
21. Glucose and amino acids are absorbed into mucosal cells primarily by which mechanism?
A. Active transport and facilitated transport
B. Simple diffusion only
C. Phagocytosis
D. Osmosis only
Answer: A. Active transport and facilitated transport
Explanation: Glucose and amino acids are absorbed by simple diffusion, facilitated transport (via carrier proteins), and active transport against concentration gradients.
22. The structural unit of the liver is called:
A. Hepatic lobule
B. Glisson's capsule
C. Hepatocyte
D. Malpighian lobule
Answer: A. Hepatic lobule
Explanation: The hepatic lobules are the structural and functional units of liver containing hepatic cells arranged in cords.
23. Glisson's capsule is a thin connective tissue sheath that covers each:
A. Hepatic lobule
B. Pancreatic acinus
C. Spleen module
D. Gastric gland
Answer: A. Hepatic lobule
Explanation: Each hepatic lobule is covered by a thin connective tissue sheath called the Glisson's capsule.
24. Which antibacterial agent present in human saliva protects against infections?
A. Lysozyme
B. Mucus
C. Pepsin
D. Secretin
Answer: A. Lysozyme
Explanation: Saliva contains lysozyme, which acts as an antibacterial agent that prevents oral infections.
25. What is the primary function of the large intestine in human digestion?
A. Absorption of water, minerals, and certain drugs
B. Digestion of proteins
C. Emulsification of fats
D. Digestion of carbohydrates
Answer: A. Absorption of water, minerals, and certain drugs
Explanation: No significant digestive activity occurs in the large intestine. Its main functions are absorption of water, minerals, and drugs, and secretion of mucus.
26. Which anatomical structure attaches the tongue to the floor of the oral cavity?
A. Frenulum
B. Papilla
C. Sulcus terminalis
D. Uvula
Answer: A. Frenulum
Explanation: The tongue is a freely movable muscular organ attached to the floor of the oral cavity by the frenulum.
27. Which hormone stimulates the release of pancreatic juice and bicarbonate ions from pancreas?
A. Secretin and CCK
B. Gastrin
C. GIP
D. Insulin
Answer: A. Secretin and CCK
Explanation: Secretin acts on the exocrine pancreas and stimulates secretion of water and bicarbonate ions, while Cholecystokinin (CCK) stimulates pancreatic enzymes and bile secretion.
28. Milk protein casein is acted upon by pepsin/rennin to yield paracasein. This process is called:
A. Curdling of milk
B. Emulsification
C. Saponification
D. Assimilation
Answer: A. Curdling of milk
Explanation: Coagulation or curdling of milk converts soluble casein into insoluble calcium paracaseinate for easier protein digestion.
29. The process by which absorbed nutrients reach the tissues and are utilized for activities is called:
A. Assimilation
B. Absorption
C. Ingestion
D. Defecation
Answer: A. Assimilation
Explanation: The absorbed substances finally reach the tissues which utilize them for their activities; this process is called assimilation.
30. A blind sac located at the junction of the small and large intestine which hosts symbiotic microorganisms is:
A. Caecum
B. Colon
C. Rectum
D. Vermiform appendix
Answer: A. Caecum
Explanation: The caecum is a small blind sac which hosts some symbiotic micro-organisms and leads into the colon.
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