Evaluate the following statements regarding protein digestion and select the correct combination:
I. In the stomach, pepsin converts proteins into proteoses and peptones. II. In the small intestine, trypsin, chymotrypsin, and carboxypeptidases act on partially hydrolysed proteins to form dipeptides. III. Dipeptidases of succus entericus convert dipeptides into amino acids. IV. Aminopeptidases are secreted by the gastric mucosa to assist pepsin.
Select the correct option.
Statements I, II and III are correct. Pepsin converts proteins into proteoses and peptones. Pancreatic proteases further digest them into dipeptides, which are finally converted into amino acids by intestinal dipeptidases. Statement IV is incorrect because aminopeptidases are intestinal enzymes, not gastric secretions.
Question 12 of 100
📘 CLASS XI
Analyze the statements regarding fat digestion and choose the correct option:
I. Fats are broken down by lipases with the help of bile into diglycerides and monoglycerides. II. Gastric glands do not secrete any lipase, hence fat digestion is completely absent in the stomach. III. Intestinal juice contains lipases which finally convert di- and monoglycerides into fatty acids and glycerol. IV. Emulsification of fats by bile salts is a prerequisite for efficient lipase activity.
Select the correct option.
Statement I is correct because pancreatic lipase digests fats into diglycerides and monoglycerides in the presence of bile. Statement II is incorrect because gastric glands secrete small amounts of gastric lipase. Statement III is correct because intestinal lipases complete fat digestion into fatty acids and glycerol. Statement IV is correct because emulsification greatly enhances lipase action.
Question 13 of 100
📘 CLASS XI
Regarding nucleic acid digestion in the small intestine, which of the following statements are correct?
I. Nucleases in the pancreatic juice act on nucleic acids to form nucleotides. II. Nucleotidases in succus entericus convert nucleotides into nucleosides. III. Nucleosidases in succus entericus convert nucleosides into sugars and nitrogenous bases. IV. Nucleic acid digestion begins in the stomach under the influence of highly acidic HCl.
Select the correct option.
Statements I, II and III are correct. Pancreatic nucleases digest nucleic acids into nucleotides, which are converted into nucleosides by nucleotidases and finally into sugars and nitrogenous bases by nucleosidases. Statement IV is incorrect because nucleic acid digestion begins in the small intestine, not in the stomach.
Question 14 of 100
📘 CLASS XI
Assess the statements regarding absorption mechanisms in the intestinal mucosa and choose the correct combination:
I. Small amounts of monosaccharides like glucose, amino acids, and chloride ions are generally absorbed by simple diffusion. II. Glucose and amino acids are also absorbed with the help of carrier proteins, which is called facilitated transport. III. Active transport occurs against the concentration gradient and requires energy. IV. Nutrients like amino acids, glucose, and sodium ions (Na+) are absorbed into the blood by active transport.
Select the correct option.
All four statements are correct. Small quantities of glucose, amino acids and chloride ions are absorbed by simple diffusion. Carrier proteins mediate facilitated transport of glucose and amino acids. Active transport requires energy and is responsible for absorption of glucose, amino acids and sodium ions against their concentration gradient.
Question 15 of 100
📘 CLASS XI
Read the statements about fat absorption and select the correct combination:
I. Fatty acids and glycerol, being insoluble, cannot be absorbed directly into the blood. II. They are first incorporated into small, water-soluble droplets called micelles, which move into the intestinal mucosa. III. In the mucosal cells, they are re-formed into very small, protein-coated fat globules called chylomicrons. IV. Chylomicrons are directly absorbed into the blood capillaries of the intestinal villi.
Select the correct option.
Statements I, II and III are correct. Fatty acids and glycerol first form micelles to enter intestinal mucosal cells, where they are reassembled into triglycerides and packaged as chylomicrons. Statement IV is incorrect because chylomicrons enter the lymphatic lacteals first and later reach the bloodstream.
Question 16 of 100
📘 CLASS XI
Which of the following statements about absorption in different parts of the digestive system is/are correct?
I. In the mouth, certain drugs coming in contact with the mucosa of the mouth and lower side of the tongue are absorbed. II. In the stomach, absorption of water, simple sugars, and alcohol takes place. III. The small intestine is the principal organ for absorption of nutrients. IV. In the large intestine, maximum absorption of glucose and amino acids occurs.
Explanation: Statements I, II, and III are correct. Certain drugs are absorbed through the mucosa of the mouth and lower side of the tongue. Water, simple sugars, and alcohol are absorbed in the stomach. The small intestine is the principal site for nutrient absorption. Statement IV is incorrect because the large intestine mainly absorbs water, minerals, and certain drugs, while glucose and amino acids are absorbed in the small intestine.
Question 17 of 100
📘 CLASS XI
Read the following statements regarding the large intestine and choose the correct set:
I. Caecum is a small blind sac which hosts some symbiotic micro-organisms. II. The vermiform appendix is a vestigial organ arising from the caecum. III. The colon is divided into three parts: an ascending, a transverse, and a descending part. IV. Significant chemical digestive activity occurs in the colon.
Explanation: Statements I, II, and III are correct. The caecum is a blind sac containing symbiotic microorganisms. The vermiform appendix arises from the caecum and is vestigial. The colon consists of ascending, transverse, and descending parts. Statement IV is incorrect because no significant digestive activity occurs in the large intestine.
Question 18 of 100
📘 CLASS XI
Assess the correctness of the following statements regarding the regulation of GI tract activities:
I. Salivary secretion is stimulated by the sight, smell, or presence of food in the oral cavity. II. Gastric and intestinal secretions are stimulated by neural signals. III. The muscular activities of different parts of the alimentary canal are completely independent of the CNS. IV. Local hormones produced by gastric and intestinal mucosa carry out hormonal control of digestive juice secretion.
Explanation: Statements I, II, and IV are correct. Salivary, gastric, and intestinal secretions are stimulated through neural reflexes, and local hormones regulate digestive juice secretion. Statement III is incorrect because muscular activities of the alimentary canal are regulated by both local neural mechanisms and the Central Nervous System (CNS).
Question 19 of 100
📘 CLASS XI
Regarding digestive system disorders, evaluate the following statements and choose the correct combination:
I. In Jaundice, the liver is affected and skin and eyes turn yellow due to the deposit of bile pigments. II. Vomiting is a reflex action controlled by the vomit centre in the medulla. III. Diarrhoea increases the absorption of food due to rapid bowel movement. IV. In constipation, the faeces are retained within the colon because bowel movements occur irregularly.
Explanation: Statements I and II are correct. Jaundice results from liver disorders causing deposition of bile pigments, leading to yellowing of the skin and eyes. Vomiting is controlled by the vomit centre in the medulla. Statement III is incorrect because diarrhoea reduces food absorption due to increased bowel movement. Statement IV is incorrect because in constipation, faeces are retained in the rectum, not the colon.
Question 20 of 100
📘 CLASS XI
Read the statements regarding histology of the duodenum and identify the correct combination:
I. Glands are present in the sub-mucosa of the duodenum, known as Brunner's glands. II. Brunner's glands secrete mucus and help in providing an alkaline pH (7.8) for intestinal enzymes. III. The duodenum mucosa forms irregular folds called rugae. IV. In the duodenum, the muscularis layer is completely absent.
Explanation: Statements I and II are correct. Brunner's glands are present in the submucosa of the duodenum and secrete mucus and bicarbonate to maintain an alkaline pH of about 7.8. Statement III is incorrect because rugae are folds of the stomach, whereas the small intestine has villi. Statement IV is incorrect because the muscularis layer is present throughout the alimentary canal, including the duodenum.
