Important Questions for CBSE Class 11 Biology Chapter 16 - Digestion and Absorption

1 Marks Questions

1. Name the secretions of Goblet cell & parietal cells.

Ans: Goblet cells secrete mucus. Parietal cells secrete hydrochloric acid and intrinsic factors.

2. Name the three parts of the small intestine of man.

Ans: The three parts of the small intestine of man are Duodenum, Jejunum and ileum.

3. Which is the largest gland in our body?

Ans: The largest gland in our body is the Liver.

4. What is the main function of bile salt?

Ans: It reduces the surface tension of fat droplets causing their breakdown into many small ones.

5. Name the watery fluid secreted from Bruner’s gland in the duodenum

Ans: Mucoid fluid is secreted from Bruner’s gland in the duodenum.

6. What is atheroma?

Ans: Atheroma is the deposition of cholesterol on the walls of arteries.

7. What is egestion?

Ans: Undigested food is expelled from the body.

8. What are micelles?

Ans: Monoglycerides, long-chain fatty acids, and digested lipids combine with bile salts to produce micelles, which are small spherical droplets.

9. What are crypts of lieberkuhn?

Ans: Pits in the gastrointestinal tract wall's submucosa.

10. What do you mean by the term malnutrition?

Ans: The stale of health due to improper intake of food or nutrients. It includes both undernutrition and overnutrition.

11. Name the hardest substance in the body?

Ans: Enamel is the hardest substance in the body.

12. What is a lacteal?

Ans: Lacteal is a Lymph vessel found in villi.

13. Name the small projections, found on the upper surface of the tongue

Ans: Papillae, the small projections, are found on the upper surface of the tongue.

14. Mention the function of epiglottis?

Ans: Food should not be allowed to enter the glottis.

15. Write the name of major parts of the stomach.

Ans: Cardiac, fundic, pyloric are the major parts of the stomach.

16. Name the enzyme that digests fast. Mention the end products of fat digestion.

Ans: Lipase, fatty acids, and glycerol are the enzymes.

17. In which part of the alimentary canal does absorption of water, simple sugars, and alcohol takes place?

Ans: Stomach absorbs water, simple sugars, and alcohol.

18. Why are proteases generally released in inactive form?

Ans: They will begin digesting the membranes and muscles of the alimentary canal if released inactive form.

19. Trypsinogen is an inactive enzyme of pancreatic juice. An enzyme, enterokinase, activate it. Which tissue/cell secretes the enzyme and how is it activated?

Ans: Intestinal mucosa is an inactive enzyme of pancreatic juice.

$\text { Trypsinogen } \stackrel{\text { enterokinase }}{\longrightarrow} \text { Trypsin } \rightarrow \text { Proteins } \rightarrow \text { Peptides }$

20. What is the role of insulin?

Ans: Metabolism of sugar is the role of insulin

2 Marks Questions

1. What is the role of micelles in fat absorption?

Ans: During digestion, fat in the colon is transformed into monoglycerides, diglycerides, and fatty acids, all of which are water-insoluble. They can't be absorbed directly from the contents of the intestine. Bile salts convert them into micelles, which are small, spherical, and water-soluble droplets. Fatty acids, glycosides, sterols, and fat-soluble vitamins are absorbed into the intestinal cells via these micelles.

2. Give two functions of trypsin?

Ans: 1) Trypsin converts chymotrypsinogen into chymotrypsin.

$\text { Pepsinogen } \stackrel{\text { HCL }}{\longrightarrow} \text { Pepsin (active) }$

2) Trypsin degrades proteoses and peptones, converting them to peptides.

$\text { Trypsin }+\text { Peptones }+\text { Protcoses } \rightarrow \text { Peptides }$

3. What are the specific functions of food?

Ans: The following are some of the specific roles of food:

(i) Food that is oxidized in the body provides energy for many processes.

(ii) Its purpose is to provide the body with the necessary materials for growth and development.

(iii) It also acts as a reserve element, primarily in the form of fat and glycogen. These can be used in the event of an emergency.

(iv) It defends the body from sickness.

4. How does fat absorption take place?

Ans: Fat absorption takes place in the form of monoglycerides and fatty acids. These are resynthesized into triglycerides, which then mix with cholesterol to form cholesterol. They combine to generate chylomicrons, which circulate through the lymphatic system.

5. How is food absorbed?

Ans: The food eaten up by individuals is in complex form. In different regions of the alimentary canal, digestive glands emit enzymes that digest the food into a simpler form, primarily soluble form. The fatty acids and glycerol in the digested food are absorbed through the intestinal wall via lacteals. Water absorption occurs in the colon as carbohydrates, amino acids, salts, and water move through the bloodstream.

6. What are enzymes?

Ans: Enzymes are defined as "an organic catalyst found in a living creature that modifies the outcome of the reaction but remains unchanged at the end of the reaction, and is created by the living organism but is not itself alive."

7. If a major part of the small intestine of a mammal be removed, will this affect the absorption of food?

Ans: Only the small intestine absorbs most of the food, while the stomach absorbs only a little portion of the water. So, if the major part of the small intestine is removed and that seriously affects the absorption of digested food.

8. What is the role of micelles in fat absorption?

Ans: Fats are broken down into monoglycerides, diglycerides, and fatty acids, which are water-insoluble. These are first integrated into micelles, which are small, spherical, and water-soluble droplets. Micelles aid in the digestion of fatty acids, glycerols, sterols, and fat-soluble vitamins into intestinal cells.

9. Differentiate chylomicron & micelles based on their structural components.

Ans: The difference between chylomicrons and Micelles is as follows.

10. What is emulsification? Where and how does it occur?

Ans: The process of breakdown of large fat droplets into smaller ones. It is found in the small intestine. It is brought about by bile salts through the reduction of surface tension of large fat droplets.

11. Name three parts of the large intestine. Which vestigial organ arises from the first part of it?

Ans: Cancun, colon and rectum, Vermiform appendix. Are the three parts of the large intestine.

12. Name the stand which performs/acts as exocrine and endocrine. Also name the products which are secreted by it.

Ans: Pancreas. Exocrine secretion is enzyme-rich pancreatic juice, whereas exocrine secretions are hormones such as insulin and glucagon.

13. The wall of the alimentary canal is made up of four layers. Give the names of these four layers.

Ans: Serosa, muscularis, submucosa and mucosa are the four layers.

14. In which part of the digestive system the absorption of the following substances takes place?

(a) Certain drugs 

(b) Glucose, fructose and fatty acids 

(c) Water, some minerals and drugs 

(d) Simple sugar and alcohol

Ans: (a) Mouth

(b) Small intestine 

(c) Large intestine 

(d) Stomach

3 Marks Questions

1. How is DNA content in our food digested in the body?

Ans: The enzymes in pancreatic juice and succus entericus break down the DNA content in the intestine region of our alimentary canal.

DNA content $\dfrac{\text { Deoxyribonucleate }}{\text { Enzyme }} \rightarrow$ Deoxyribonucleotides

Deoxyribonucleotides $=$ е $\mathrm{PO}_{4}+$ Deoxyribonucleotides

Deoxyribonucleotides $\dfrac{\text { Nucleosidase }}{\text { Enzyme }} \rightarrow$ Deoxyribose $+$ Purine +Pyrimidine

2. How would it affect the digestion of proteins if there is blockage in the pancreatic duct?

Ans: Pancreatic duct in addition to pancreatic juice brings bile juice also. The pancreatic juice contains many enzymes that act as follows.

1. Trypsin — This enzyme transforms protein, proteases, and peptones into amino acids.

2. Amylopsin — This enzyme transforms starch into soluble sugars.

3. Steapsin or Lipase - This enzyme emulsifies lipids and converts them to fatty acids and glycerol.

As a result, if the pancreatic duct is blocked, there will be no digestion of proteins, lipids, or carbs since the digestive enzymes will be missing.

3. What is the action of salivary amylase? Differentiate between lipases and peptidases?

Ans: Starch is broken down into sugars by salivary amylase.

Lipases and Peptidases are two different types of enzymes.

4. It is not necessary to produce amylase in an active form in our body. But it is not in the case of trypsin. Given reasons

Ans: Salivary amylase is a digestive enzyme that is secreted in the buccal cavity and digests starch and sugar (carbohydrates). Because amylase does not act on the proteins that make up animal tissues (buccal cavity), it is secreted in its natural state.

Trypsin – It acts on proteins. The wall of the alimentary canal is also made of protein. As a result, it is critical that it is secreted in an inactive form and that it becomes active when dietary protein is available in the alimentary canal. As a result, it is secreted in an inactive state to prevent harm (body digestion).

5. Describe coagulation of milk in the alimentary canal?

Ans: Protein digestion begins when food or milk reaches the stomach. Pepsinogen is converted to pepsin by HCl, which speeds up the digestion of milk proteins (casein). It transforms soluble casein to paracasein, which then crystallises as calcium paracaseinate to form solid curd (milk coagulation). There is milk–a coagulating enzyme called rennin which is found in calf gastric juice. Rennin is released as pro-rennin (an inactive form), but it hydrolyzes casein to paracasein in the presence of HCl, causing milk to coagulate.

6. Name three enzymes secreted by the pancreas that specify the substance and the product of each.

Ans: Pancreas is a composite gland. It has exocrine and endocrine parts. Pancreatic juice is secreted by the exocrine pancreas. It contains trypsin, amylopsin and steapsin

1. Trypsin is a protein that transforms proteins, peptones, and proteoses into amino acids.

2. Amylopsin — This enzyme transforms starch into soluble sugars.

3. Steapsin or Lipase - This enzyme emulsifies lipids and converts them to fatty acids and glycerol.

5 Marks Questions

1. Draw a labelled diagram of the human alimentary canal & Describe its different parts.

Ans: The alimentary canal of man is a long-coiled tube of varying diameters. Its length varies between 8 and 10 metres. It is divisible into the following parts

1. Oral Cavity – It is the initial enlarged part of the alimentary canal. It opens by mouth and consists of lips, cheeks, gums, teeth and the palate and its muscles. The salivary glands open into the oral cavity. 

2. Pharynx - The pharynx is where the oral cavity meets the pharynx.

3. Oesophagus - A 10-inch-long muscular tube that delivers food from the mouth to the stomach, where it meets the cardiac stomach.

4. Below the diaphragm is the stomach, which is a sac-like structure. Gastric gland ducts open into many small gastric pits on the stomach's wall.

5. Small Intestine – This is a tube-like structure that measures about 5-7 metres in length. It is divided into three sections: the duodenum, jejunum, and ileum. The initial component of the digestive system is the duodenum, which is shaped like u. This will open the pancreatic duct and the bile duct.

6. Large Intestine - The length of the large intestine is approximately 1.5 metres. It consists of the caecum, colon, and rectum, as well as the vermiform appendix. The anus opens the rectum to the outside. 

   

2. Name the enzymes for protein digestion in the gastric, pancreatic, and intestinal, the substrate they digest and products of their action.

Ans: The enzymes for protein digestion in the gastric, pancreatic, and intestinal substrate they digest and products of their activities are as follows,

3. Explain the absorption of digested products?

Ans: Absorption of Digested Products - Absorption is defined as "the process by which digestion's end products pass past the intestinal mucosa and into the blood or lymphatic system." Absorption is accomplished by three mechanisms: passive, active, and transport ways. Monosaccharides like glucose, amino acids, and certain electrolytes like chloride are absorbed primarily through simple diffusion across a concentration gradient, but other substances like fructose and some amino acids are absorbed with the help of transport ions like It's referred to as assisted transportation.

The osmotic gradient controls water transfer. Active transportation is energy-intensive and occurs in the face of a concentration gradient. Amino acids, monosaccharides like glucose, and electrolytes can all be absorbed into the bloodstream through active transport.

Because glycerol and fatty acids are insoluble, they are not taken into the bloodstream. Micelles are microscopic droplets that contain them. They infiltrate the intestinal mucosa. They produce chylomicrons, which are protein-coated fat globules that are very tiny. Lymph vessels or lacteals deliver the chylomicrons to the villi. They eventually release substances that have been taken into the bloodstream.

In the alimentary canal, mouth, stomach, small intestine, and large intestine, numerous substances are absorbed. The small intestine is where the most absorption occurs. It has villi in the small intestine.

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