AIIMS Digestion and Absorption Assertion and Reason

1. Assertion (A) : Liver is the largest gland of human body.
Reason (R) : Liver contains islets of Langerhans that are phagocytic in nature.
2. Assertion (A) : Carbohydrates are more suitable for the production of energy in the body than proteins and fats.
Reason (R): Carbohydrate molecules contain relatively less oxygen than the others, and hence require less molecular oxygen for oxidation.
3. Assertion (A): Vermiform appendix is a vestigial organ in human body.
Reason (R) : It does not participate in digestion.
4. Assertion (A): The digestive action of salivary amylase stops when the swallowed food enters the stomach. Reason (R): Salivary amylase is inactivated at the low pH of gastric juice.
5. Assertion (A) : Enterokinase converts trypsinogen of pancreatic juice into trypsin.
Reason (R): Trypsin acts best at an alkaline pH provided in small intestine.

6. Assertion (A) : Large intestine is the rear division of the vertebrate intestine that is divided into the caecum, colon and rectum.
Reason (R): It is called ‘large’ because it is longer than the small intestine.
7. Assertion (A) : Liver secretes bile that gets stored in the hepatic lobules.
Reason (R) : Bile contains enzyme lipase that acts on fats.
8. Assertion (A): Pepsin present in the gastric juice poses no threat to the stomach.
Reason (R) : Pepsin is secreted in an inactive form.
9. Assertion (A): Fatty acids and glycerol are not absorbed into the blood directly.
Reason (R) : Fatty acids and glycerol are insoluble in water.
10. Assertion (A) : Peyer’s patches are simple, tubular structures which occur throughout the small intestine between the villi.
Reason (R): Peyer’s patches secrete digestive enzymes and mucus.

Answers

1. (c)
Explanation of ‘A’ & ‘R’Liver is the largest gland of human body. It lies in the upper right side of the abdominal cavity just below the diaphragm. It contains phagocytic cells known as Kupffer cells that eat out worn out WBCs, RBCs and bacteria.
The endocrine part of the pancreas consists of groups of islets of Langerhans, each consisting of cells that secrete hormones to be passed into the circulating blood.
R e su lt: Hence, it is proved that ‘A’ is true and ‘R’ is
false, so the answer is option (c).
2. (c)
Explanation of ‘A’ & ‘R’ Carbohydrates e.g., glucose, fructose, sucrose, starch etc. are used primarily as sources of chemical energy to be either metabolized immediately as glucose or stored as glycogen. Carbohydrates are more suitable for the production of energy in the body than proteins and fats because carbohydrate molecules contain relatively more oxygen than the others, hence require less molecular oxygen for oxidation.
Result: Hence, it is proved that ‘A’ is true and ‘R’ is false, so the answer is option (c).
3. (a)
Explanation of A’ & ‘R’ Vermiform appendix, an outgrowth of the caecum, is a vestigial organ in human body and does not perform any function. Infact, decay of food or worm infection leads to inflammation of appendix (appendicitis). In such cases, it has to be removed immediately so that it does not burst and spread infection in the abdominal cavity.
Result: Hence, it is proved that both ‘A’ and ‘R’ are true and as ‘R’ is the correct explanation of A’, so the answer is option (a).
4. (a)
Explanation of A’ & ‘R’ Salivary amylase is an enzyme present in the saliva having pH 6.8. When food is mixed with saliva in the oral cavity, this enzyme converts starch into maltose, isomaltose and a-dextrins. When this semi- digested food enters into the stomach the digestive action of salivary amylase stops. This is because, the gastricjuice secreted in the stomach has a pH 1.5 – 2.5 (very acidic) and salivary amylase gets inactivated at such a low pH.
Result: Hence, it is proved that both A’ and ‘R’ are true and as ‘R’ is the correct explanation of A’, so the answer is option (a).
5. (b)
Explanation of ‘A’ & ‘R’In the presence of enzyme enterokinase of intestinal juice, inactive trypsinogen is converted to active trypsin. Trypsin then activates chymotrypsinogen and procarboxypeptidase into chymotrypsin and carboxypeptidase respectively.The bile provides alkaline medium for various reactions. Trypsin acts best at an alkaline pH provided in the small intestine by the bicarbonates of pancreatic and intestinal juices and bile.
Result: Hence, it is proved that both A’ and ‘R’ are true but as ‘R’ is not the correct explanation of A’, so the answer is option (b). 6
6. (c)
Explanation of A’ & ‘R’Intestine is a long, continuous tube running from the stomach to the anus. Intestine is divided into two parts: small intestine and large intestine. Small intestine is about 20 feet long (longest part of the alimentary canal) and about an inch in diameter. It is further divided into three parts: duodenum, jejunum and ileum. Large intestine is the rear part of the intestine and is divided into caecum, colon and rectum. It is about 5 feet long and about 3 inches in diameter. Thus, large intestine is called large because of its larger diameter than that of the small intestine.
Result: Hence, it is proved that A’ is true and ‘R’ is false, so the answer is option (c).
7. (d)
Explanation of A’ & ‘R’ :- Bile is secreted by the liver but it gets stored in the gall bladder which is a pear shaped sac like structure attached to the posterior surface of the liver by connective tissue. Bile contains no enzyme but it activates the enzyme lipase present in the pancreatic juice and intestinal juice.
Result: Hence, it is proved that both A’ and ‘R’ are false, so the answer is option (d).
8. (a)
Explanation of A’ & ‘R’ Pepsin is a protein digesting enzyme present in the gastric juice. It acts on proteins to convert them into proteoses and peptones. It poses no threat to the epithelial lining of the stomach as it is secreted in an inactive form called pepsinogen. When food enters into the stomach, pepsinogen is converted into pepsin by HCI present in the gastric juice. The mucus secreted by the goblet cells of the stomach also protects the epithelial surface from digestion by pepsin and excoriation by HCI.
Result: Hence, it is proved that both A’ and ‘R’ are true and as ‘R’ is the correct explanation of A’, so the answer is option (a).
9. (a)
Explanation of A’ & ‘R’ :- Fatty acids and glycerol being insoluble in water cannot be absorbed into the blood directly. They are first incorporated into small, spherical, water soluble droplets called micelles with the help of bile salts in the intestinal lumen. From the micelles, fatty acids, glycerides, sterols and fat soluble vitamins are absorbed into the intestinal cells by diffusion where they are resynthesized in the endoplasmic reticulum and are converted into very small fat molecules called chylomicrons. From the intestinal cells, chylomicrons are released into the lymph present in the lacteals. From the lacteals, chylomicrons are carried to the blood stream directly and enter cells as fatty acids and glycerol.
Result: Hence, it is proved that both A’ and ‘R’ are true and as ‘R’ is the correct explanation of A’, so the answer is option (a).
10. (d)
Explanation of A’ & ‘R’ Peyer’s patches or lymph nodules are present in groups along the ileum (part of small intestine). They are distinguishing characteristic of the ileum, and produce lymphocytes. The simple, tubular structures that occur throughout the small intestine between the villi are known as crypts of Lieberkuhn. They secrete digestive enzymes and mucus.
Result: Hence, it is proved that both A’ and ‘R’ are false, so the answer is option (d).

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Comment ( 1 )
  1. mohamed
    February 18, 2016 at 1:38 pm
    Reply

    nice

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