CBSE Questions for Class 11 Medical Biology Digestion And Absorption Quiz 4 - MCQExams.com

• Ptylin is the salivary amylase that converts the starch into the dextrin and maltose. 
• 30% of the starch is hydrolyzed by the action of amylase.
• Gastrin is a hormone produced by the stomach, which stimulates the release of gastric acid.
• Pancreatic amylase converts polysaccharides (Starch) into Disaccharides.
• Pepsinogen(proenzyme) is converted into Pepsin by HCl present in gastric juice. Pepsin, in turn, converts protein into peptones & proteoses.

• During digestion, starch is partially transformed into maltose by the pancreatic or salivary enzymes called amylases.
• Maltase is secreted by the intestine that converts maltose into glucose. Hence, Starch is converted to maltose by the action of Amylase.

• The digestion process of polysaccharides such as starch will begin in the mouth where it is hydrolyzed by salivary amylase. Carbohydrase enzymes break down starch into sugars.
• Protein digestion occurs in the stomach and the duodenum through the action of three main enzymes: pepsin, secreted by the stomach, and trypsin and chymotrypsin, secreted by the pancreas.
•  Lactose is normally broken down by an enzyme called lactase, which is produced by cells in the lining of the small intestine.
  So, the correct answer is option B. 

• In the duodenum, trypsin catalyzes the hydrolysis of peptide bonds, breaking down proteins into smaller peptides. 
• The peptide products are then further hydrolyzed into amino acids via other proteases, and then absorption occurs into the bloodstream. Hence, Trypsin digests proteins into amino acids.

Correct Option: B
Explanation:

• Amylase is the enzyme that catalyses the hydrolysis of starch into simple sugars.
• So if salivary amylase is lacking in saliva, the breakdown of starch is affected. 
• Other phenomena such as protein breakdown to amino acids by protease enzyme and fat breakdown by bile in the small intestine. Whereas vitamins are absorbed by the small intestine.
• Hence, if salivary amylase is lacking in the saliva, then in the mouth starch will not break down in sugar.

• The digestive glands (salivary glands, pancreas, liver, and gallbladder) produce or store secretions that the body carries to the digestive tract in ducts and breaks down chemically. 
• The teeth help in mechanical digestion by masticating (chewing) food.
• The whole process starts in the oral cavity, where the saliva from the salivary glands mixes with the food and starts to begin the breakdown of food. This semi-digested food then travels down to the small intestine, where secretions from the liver, gallbladder, and pancreas further act on the food particles. Hence, Teeth are not only part of the digestive system that physically breaks down food.
• So, the correct answer is 'False'.

• Digestion starts from the mouth and ends at large intestine. When the food enters mouth (ingestion), it is broken into small pieces by the teeth and acted upon by salivary amylase. 
• Then it travels down the oesophagus to the stomach, where digestive enzymes from the pancreas, gall bladder, liver and duodenum further digest it.
• Assimilation of nutrients occurs at small intestine and absorption of water and other substances happen at the large intestine before it is egested or excreted. 
• Thus, the correct answer is option D.

Correct Option: B
Explanation: 

• The liver is the largest gland in the human body. It produces bile.
• Bile is stored, concentrated and released from the gall bladder.
• When the acid food enters the small intestine the bile, pancreatic juice and intestinal juice are the secretions released into the small intestine.
• Pancreatic juice and bile are released into the small intestine through the hepato-pancreatic duct.
• Hence, the small intestine receives bile from the liver.

• Pancreatic enzymes help break down fats, proteins, and carbohydrates. The pancreatic juice secreted into the duodenum contains pancreatic enzymes (lipase, protease, amylase) to help with digestion and bicarbonate to neutralize stomach acid as it enters the small intestine.

The sacculus rotundus is the structure present at the terminal end of the ileum of the rabbit. It is rich in lymphoid tissues. Sacculus rotundus has an ileo-caecal valve due to which food comes into caecum and then returns to the large intestine. It does not have any specific digestive function in rabbit, though its wall has lymph gland, which secretes lymphocytes which destroy the bacteria present in the food. 

$$\textbf{Correct answer: C}$$ 

$$\textbf{Option (A):}$$ 

$$\bullet$$ The intestinal lining of the ileum produces specific proteases and maltase.

$$\bullet$$ It is important for the final stages of digestion of proteins and carbohydrates so that they can be absorbed. 

$$\textbf{Option (B):}$$ 

$$\bullet$$ Pancreas is responsible for the production of trypsinogen. It gets converted to active trypsin as it enters the duodenum. 

$$\bullet$$ This digests the partially digested protein from the food materials. It produces small and peptides and amino acids.

$$\textbf{Option (C):}$$ 

$$\bullet$$ Chief cells of the stomach secrete the proenzyme pepsinogen. It gets activated in the acidic pH of the stomach and functions as pepsin. 

$$\bullet$$ The pepsin digests the dietary protein present in food that reaches the stomach. 

$$\bullet$$ This is the strongest proteolytic enzyme as it can convert the larger molecules of protein into smaller polypeptide chains.

$$\bullet$$ This makes it easier for the digestion of proteins in the intestine. 

$$\textbf{Option (D):}$$ 

$$\bullet$$ Liver is responsible for the production of bile.

$$\bullet$$ Bile salts facilitate the emulsification and absorption of fats.

Hence, the correct answer is option (C).

• After food is being swallowed, from the mouth it is transported to the stomach. No absorption of nutrients takes place in the mouth and oesophagus. Hence, No absorption of food takes place in the mouth and oesophagus.
• Active glucose absorption is thought to depend on a gradient of sodium ion concentration across the brush border membrane of intestinal epithelial cells. Specifically, glucose absorption was minimally reduced when intraluminal sodium concentration was reduced. Hence, Absorption of glucose depends on sodium ion.
• Pinocytosis is the absorption of liquids, whereas phagocytosis is the absorption of solid objects which are essentially food for the cell. Phagocytosis engulfs whole particles, which are later broken down by enzymes, such as cathepsins, and absorbed into the cells. Hence, Whole protein particles cannot be engulfed by pinocytosis.