Absorption of Digested Products:
1. Which of the following is an active enzyme in the pancreas?
A. Trypsinogen
B. Procarboxypeptidase
C. Chymotrypsinogen
D. Nucleases
Answer: D
Explanation: The inactive enzymes of the pancreas are trypsinogen, procarboxypeptidase and chymotrypsinogen. The other pancreatic enzymes include amylases, lipases and nucleases.
2. Which of the following enzymes activate trypsinogen?
A. Chymotrypsin
B. Enterokinase
C. Lipase
D. Bile
Answer: B
Explanation: Trypsinogen is activated by an enzyme, enterokinase, secreted by the intestinal mucosa into active trypsin, which in turn activates the other enzymes in the pancreatic juice.
3. Which of the following is not present in bile?
A. Phospholipids
B. Bilirubin
C. Biliverdin
D. Nuclease
Answer: D
Explanation: Nucleases are not present in the bile as this enzyme is the secretion of the pancreas. The bile released into the duodenum contains bile pigments like bilirubin and biliverdin, bile salts, cholesterol and phospholipids. No enzyme is present in the bile juice.
4. Which secretions constitute the intestinal juice?
A. Bile juice
B. Pancreatic juices
C. Stomach secretions
D. Secretions of brush border cells and goblet cells
Answer: D
Explanation: The intestinal mucosal epithelium has goblet cells which secrete mucus. The secretions of the brush border cells of the mucosa along with the secretions of the goblet cells constitute the intestinal juice or succus entericus.
5. Bile protects the intestinal mucosa from acid and alkaline medium.
A. True
B. False
Answer: B
Explanation: The mucus along with the bicarbonates released from the pancreas protects the intestinal mucosa from acid as well as provide an alkaline medium for enzymatic activities. Submucosal glands also help in this.
6. What are peptones?
A. Partially hydrolysed proteins
B. Completely hydrolysed proteins
C. Incompletely ligase proteins
D. Hydrolysed proteins
Answer: A
Explanation: Peptones are partially hydrolysed proteins. Proteins, proteoses and peptones in the chyme after reaching the small intestine are acted upon by the proteolytic enzymes of the pancreatic juice.
7. In the small intestine, carbohydrates are broken down into which of the following?
A. Monosaccharides
B. Disaccharides
C. Trisaccharides
D. Polysaccharides
Answer: B
Explanation: In the small intestine, carbohydrates in the chyme are hydrolysed by pancreatic amylase into disaccharides. Fats are broken down by lipases with the help of bile into di and monoglycerides.
8. Which of the following is not a product of the breakdown of nucleic acids?
A. Nucleotide
B. Nucleoside
C. Glycerol
D. Nitrogen base
Answer: C
Explanation: The nucleases in the pancreatic juice acts in nucleic acids to form nucleotides and nucleosides which are further broken down by nucleosidases to sugars and nitrogen bases.
9. Where does the breakdown of bio-macromolecules take place?
A. Ileum
B. Jejunum
C. Duodenum
D. Pancreas
Answer: C
Explanation: The breakdown of bio-macromolecules occurs in the duodenum region of the small intestine. The simple substances thus formed are absorbed in the jejunum and ileum regions of the small intestine.
10. No significant digestive activity occurs in the large intestine.
A. True
B. False
Answer: A
Explanation: No significant digestive activity occurs in the large intestine. The only known function of the large intestine is absorption of water, minerals and certain drugs. The inner layer of large intestine also secretes some amount of mucus which helps to bind the waste particles together.
11. Which valve prevents the backflow of faeces into the ileum?
A. Ileo-caecal valve
B. Pyloric sphincter
C. Sphincter of Oddi
D. Cardiac sphincter
Answer: A
Explanation: The undigested, unabsorbed substances are called faeces which enter into the caecum of the large intestine through the ileocaecal valve, which prevents the backflow of the faecal matter.
12. Where are the faeces stored till defaecation?
A. Caecum
B. Colon
C. Anus
D. Rectum
Answer: D
Explanation: The faeces are temporarily stored in the rectum till defaecation. The activities of the gastrointestinal tract are under neural and hormonal control for proper coordination of different parts.
13. Gastric and intestinal secretions are stimulated by which of the following?
A. Neural signals
B. External stimulus
C. Internal stimulus
D. Excitation of cells
Answer: A
Explanation: gastric and intestinal secretions are stimulated by neural signals. The muscular activities of different parts of the alimentary canal can also be moderated by neural mechanism, both local and through CNS.
14. What is the ultimate form of energy?
A. Heat
B. Air
C. Water
D. Sand
Answer: A
Explanation: Heat is the ultimate form of energy and that is why the energy requirements of animals, and the energy content of food, are expressed in terms of a measure of heat energy.
15. What is meant by 1 calorie?
A. Amount of heat energy required to raise the temperature of 1 kg of water
B. Amount of heat energy required to raise the temperature of 1-tonne water
C. Amount of heat energy required to raise the temperature of 1 mg water
D. Amount of heat energy required to raise the temperature of 1 g water
Answer: D
16. What is the most common ailment of the alimentary canal?
A. Inflammation
B. Jaundice
C. Diarrhoea
D. Vomiting
Answer: A
Explanation: The inflammation of the alimentary canal is the most common ailment due to bacterial or viral infections. The infections are also caused by parasites of the intestine like tapeworm, roundworm, etc.
17. Which of the following is a symptom of jaundice?
A. Bile salts deposit in the liver
B. Bile salts deposit in eyes
C. Bile pigments deposit in the liver
D. Bile pigments deposit in the eyes
Answer: D
Explanation: In jaundice, the liver is affected, skin and eyes turn yellow due to the deposition of bile pigments particularly bilirubin. It is a waste material that remains in the bloodstream after iron is removed from the blood.
18. Where is the vomiting centre present in our bodies?
A. Medulla
B. Pons
C. Cerebellum
D. Hypothalamus
Answer: A
Explanation: Vomiting is the ejection of stomach contents through the mouth. This reflex action is controlled by the vomiting centre in the medulla. A feeling of nausea precedes vomiting.
19. Which of the following is the symptom of diarrhoea?
A. Limited frequency of the bowel movement
B. No bowel movement
C. Abnormal frequency of bowel movement
D. The normal frequency of bowel movement
Answer: C
Explanation: The abnormal frequency of bowel movement and increased liquidity of the faecal discharge is known as diarrhoea. It reduces the absorption of food.
20. In constipation, there is increased liquidity of the faecal matter.
A. True
B. False
Answer: B
Explanation: In constipation, the faeces are retained within the colon as the bowel movement occurs irregularly. Increased fluidity of the faecal matter is the symptom of diarrhoea.
21. What is a bomb calorimeter?
A. Open metal chamber
B. Open brass chamber
C. The closed metal chamber filled with oxygen
D. The closed metal chamber filled with nitrogen
Answer: D
Explanation: Bomb calorimeter is a closed metal chamber which is filled with oxygen. The amount of heat liberated from the complete combustion of 1 g food in a bomb calorimeter is its gross calorific value.
22. What is the physiologic value of food?
A. The actual amount of energy combustion of 1 g of food
B. The actual amount of energy combustion of 1 Kg of food
C. The actual amount of energy combustion of 1 mg of food
D. Amount of complete combustion of 1 g food in a bomb calorimeter
Answer: A
Explanation: The actual amount of energy combustion of 1 g of food is the physiologic value of food. Physiologic value of fats and carbohydrates is 9 kcal/g and 4 kcal/g respectively.
23. What is the gross calorific value of proteins?
A. 4 kcal/g
B. 5.65 kcal/g
C. 9 kcal/g
D. 9.45 kcal/g
Answer: B
Explanation: The gross calorific value of proteins is 5.65 kcal/g while the physiologic value of proteins is 4 kcal/g. The gross calorific value of carbohydrates and fats is 4.1 kcal/g and 9.45 kcal/g respectively.
24. What is meant by absorption of food?
A. End products of digestion are thrown out of the body
B. End products of digestion are egested out of the body
C. End products of digestion are transported to the body
D. End products of digestion are passed through the intestinal mucosa
Answer: D
Explanation: Absorption is the process by which the end products of digestion pass through the intestinal mucosa into the blood or lymph. It is carried out by passive, active or facilitated transport mechanisms.
25. Which of the following is not absorbed by simple diffusion?
A. Glucose
B. Amino acids
C. Sodium ions
D. Chloride ions
Answer: C
Explanation: Sodium ions are not absorbed by simple diffusion. Glucose, amino acids and some electrolytes like chloride ions are generally absorbed by simple diffusion. The rate or passage of these ions depends upon the concentration gradients.
26. Water is transported through a facilitated diffusion mechanism.
A. True
B. False
Answer: B
Explanation: Transport of water depends upon the osmotic gradient. However, some substances like glucose and amino acids are absorbed with the help of carrier proteins. This mechanism is called facilitated transport.
27. Which of the following is transported through active transport?
A. Sodium ions
B. Chloride ions
C. Fatty acids
D. Glycerol
Answer: A
Explanation: Active transport occurs against the concentration gradient and hence requires energy. Various nutrients like amino acids, monosaccharides like glucose and electrolytes like sodium ions are absorbed into the blood by this mechanism.
28. What are chylomicrons?
A. Very large protein-coated fat molecules
B. Very large fat coated protein molecules
C. Very small protein-coated fat molecules
D. Very small fat coated protein molecules
Answer: C
Explanation: Fatty acids and glycerol being insoluble, cannot be absorbed into the blood. They are first incorporated into micelles and then are reformed into very small protein-coated fat molecules called chylomicrons.
29. Which is the principal organ for absorption?
A. Mouth
B. Stomach
C. Small intestine
D. Large intestine
Answer: C
Explanation: The principal organ for the absorption of nutrients in the small intestine. The digestion is completed here and the final products of digestion are absorbed through the mucosa into the bloodstream and the lymph.
30. What initiates a signal for defaecation?
A. Faeces in the colon
B. Faeces in the rectum
C. Faeces in the caecum
D. Faeces in the ileum
Answer: B
