Please refer to Digestion and Absorption Class 11 Biology Exam Questions provided below. These questions and answers for Class 11 Biology have been designed based on the past trend of questions and important topics in your class 11 Biology books. You should go through all Class 11 Biology Important Questions provided by our teachers which will help you to get more marks in upcoming exams.
Class 11 Biology Exam Questions Digestion and Absorption
Class 11 Biology students should read and understand the important questions and answers provided below for Digestion and Absorption which will help them to understand all important and difficult topics.
Objective Type Questions
Question. _____ opens into large intestine
Question. Vermiform appendix is _____ like projection
(a) finger like
(b) stem like
(c) hair like
(d) none of the above
Question. The descending part of colon opens in _____ which opens out through anus
(d) It’s a blind sac
Question. Serosa is the _____ layer and is made up of a _____ mesothelium
(a) Outermost, thin
(b) Innermost, thin
(c) Outermost, thick
(d) Innermost, thick
Question. Muscles are arranged into _____ circular _____ longitudinal layer in muscular cell layer
(a) Outer, Inner
(b) Inner, Outer
(c) Inner, Inner
(d) Outer, Outer
Question. Sub-mucosal layer is formed by _____ tissue
(b) Dense connective
Question. In _____ glands are also present in submucosa
Question. Mucosa has irregular folds called _____ in stomach
(d) None of these
Question. The activities of GIT are under _____ control
(c) both (a) and (b)
Question. _____ cells secrete mucus
Question. _____ and _____ required in small quantities
(a) Minerals and vitamins
(b) Water and minerals
(c) fats and proteins
(d) Carbohydrates and ammonia
Question. Conversion of complex food substances to simple absorbable forms is called _____
(d) None of the above
Question. Hardest part of body
(d) All of these
Question. The tongue is _____ organ
(a) Freely movable muscular
(c) Freely non movable
(d) Rigid but movable
Question. Small projection of tongue is known as _____
Question. Thin long tube which passes through neck, thorax, diaphragm and leads to stomach is
(a) Small intestine
Question. A muscular sphincter that regulates the opening of oesophagus into stomach
Question. Stomach is ____ shaped
Question. _____ part of stomach opens in first part of small intestine
Question. Highly coiled part of small intestine is
Very Short Answer Type Questions:
Question. Name the enzymes involved in the breakdown of nucleotides into sugars and bases?
Ans. The enzymes nucleotidases and nucleosidases are involved in the breakdown of nucleotides into sugars and bases.
Question. Trypsinogen is an inactive enzyme of pancreatic juice. An enzyme, enterokinase, activates it. Which tissue/cells secrete this enzyme?/How is it activated?
Ans. Trypsinogen is activated to trypsin by the enzyme enterokinase. This enzyme is secreted by the intestinal mucosa.
Question. What do we call the type of teeth attachment to jaw bones in which each tooth is embedded in a socket of jaws bones?
Ans. The type of attachment where teeth are embedded in the socket of jaw bone is called thecodont.
Question. Stomach is located in upper left portion of the abdominal cavity and has three major parts. Name these three parts.
Ans. The three major parts of stomach are
(a) Cardiac into which the oesophagus opens.
(b) Fundus which is commonly filled with air or gases.
(c) Pylorus which opens into small intestine (posterior part of stomach).
Question. Does gall bladder make bile?
Ans. Gall bladder is not associated with the bile formation rather it is involved in the storage of bile. Bile is secreted from the hepatic cells of the liver.
Question. Define digestion in one sentence.
Ans. The process of conversion of complex food substances to simple absorbable forms by mechanical and biochemical methods is called digestion.
Question. Correct the following statements by deleting one of entries (given in bold).
(a) Goblet cells are located in the intestinal mucosal epithelium and secrete chymotrypsin/mucus.
(b) Fats are broken down into di-and monoglycerides with the help of amylase/lipases.
(c) Gastric glands of stomach mucosa have oxyntic cell/chief cells which secrete HCl.
(d) Saliva contains enzymes that digest starch/protein
Ans. (a) Goblet cells are located in the intestinal mucosal epithelium and secrete mucus.
(b) Fats are broken down into di and monoglycerides with the help of lipases.
Question. The food mixes thoroughly with the acidic gastric juice of the stomach by the churning movements of its muscular wall. What do we call the food then?
Ans. The food is stored in stomach for 4-5 hours, and it gets thoroughly mixed with the acidic gastric juice of stomach by the churning movements of its muscular wall. The food at this stage is called as chyme.
Question. In which part of alimentary canal does absorption of water, simple sugars and alcohol takes place?
Ans. The absorption of water, simple sugars, alcohol and some lipid soluble drugs take place by the stomach wall.
Short Answer Type Quesations:
Question. List the organs of human alimentary canal and name the major digestive glands with their location.
Ans. Human digestive system consists of two main parts, alimentary canal and digestive glands.
Alimentary canal comprises of following parts
(i) Mouth (ii) Pharynx (iii) Oesophagus
(iv) Stomach (v) Small intestine (vi) Large intestine
(vii) Rectum (viii) Anus
Digestive glands include
(i) Salivary glands are situated just outside the buccal cavity and secrete salivary juice into it.
(ii) Liver is the largest gland in the body, situated in the abdominal cavity just below the diaphgram and has two lobes. It secreates bile which helps in the digestion of fats.
(iii) Pancreas is the compound organ situated between the limbs of U-shaped duodenum acting as endocrine and exocrine organ. The exocrine portion secretes pancreatic juice where endocrine portion secretes hormones like insulin and glucagon.
Question. What is the role of gall bladder? What may happen if it stops functioning or is removed?
Ans. Gall Bladder is a pear-shaped sac-like structure, that is attached to the posterior surface of the liver by a connective tissue. The bile secreted by the hepatic cells of liver, passes
through the hepatic ducts and gets stored and concentrated in the gall bladder.
Non-functioning and removal of gall bladder would be bile to simply run in the continuous stream from the liver into the intestine. It would not be as concentrated as the bile started in gall bladder actually is. The body gradually adjust to it but a low fat diet is recommonded because fat digestion is significantly reduced after gall bladder removal.
Question. What is pancreas? Mention the major secretions of pancreas that are helpful in digestion.
Ans. The pancreas is a compound (both exocrine and endocrine) elongated organ situated between the limbs of ‘U’ shaped duodenum.
Internal structure of pancreas consist of two parts, i.e., the exocrine and endocrine part.
(i) Exocrine part consists of rounded lobules called acini that are involved in the secretion of alkaline pancreatic juice of pH 8.4. The pancreatic juice is mainly involved in the digestion of starch, proteins, fats and nucleic acids.
(ii) Endocrine part is involved in the secretion of hormones like, insulin and glucagon that regulate glucose metabolism.
Question. How are the activities of gastro-intestinal tract regulated?
Ans. The activities of the Gastro-Intestinal Tract (GIT) are under neural and hormonal control for proper coordination amongst different parts. The gastrointestinal tract is innervated by intrinsic nerves as well as by extrinsic nerves.
The intrinsic neural system, also called the enteric neural system consists of (i) Meissner’s plexus situated in the submucosa and (ii) Auerbach’s plexus situated in the muscular layer. The enteric neural system controls most of the gastrointestinal functions like secretion and motility.
The extrinsic innervation of the gut consists of parasympathetic and sympathetic nerves which can modify the activity of intrinsic neural system in response to reflex activity initiated by GIT or from other body parts.
The sight, smell and the presence of food in the oral cavity can stimulate the secretion of the saliva through vagus nerve. Gastric and intestinal secretions are also stimulated by neural signals. The muscular activity of different parts of the alimentry canal can also be moderated by neural mechanisms, both local and through CNS.
Hormonal control of the secretions of digestive juice is carried out by the local hormones produced by the gastric and intestinal mucosa. These include gastrin (stimulate release of gastric juice), enterogastrone (inhibits gastric secrection and motility), secretin (decreases gastric secretion), duodocrinin (stimulate Brunner’s gland) etc.
Question. What are three major types of cells found in the gastric glands? Name their secretions.
Ans. Gastric glands process three major types of cells namely
(i) Mucous neck cells (Goblet cells) These cells are present throughout the epithelium of gastrointestinal tract and are involved in the secretion of mucus.
(ii) Peptic or Chief cells (Zymogenic cells) These cells are usually basal in location and are involved in the secretion of gastric digestive enzymes such as proenzymes pepsinogen and prorennin.
(iii) Parietal or oxyntic cells These cells are large and most numerous present on the side walls of the gastric glands. They are involved in the secretion of HCl and Castlis
Intrinsic Factor (CIF). (factor essential for the absorption of vitamin-B12 in ileum).
Question. Distinguish between constipation and indigestion. Mention their major causes.
Ans. Constipation is characterised by small amounts of hard, drybowel movements usually fever than three times a week. In constipation, the faeces are retained within the rectum as the bowel movement occurs irregularly. The causes for constipation involve water deficiency, lack of roughage in diet, spasm of colon, lack of exercise, emotional stress and certain drugs.
Indigestion is the condition in which the food is not properly digested leading to a feeling of fullness. The cause of indigestion are inadequate enzyme secretion, anxiety, food poisoning, over eating and spicy food consumption.
Question. Correct the statements given below by the right option shown in the bracket against them.
(a) Absorption of amino acids and glycerol takes place in the (small intestine/ large intestine).
(b) The faeces in the rectum initiate a reflex causing an urge for its removal (neural/ hormonal).
(c) Skin and eyes turn yellow in infection (liver/stomach).
(d) Rennin is a proteolytic enzyme found in gastric juice in (infants/ adults).
(e) Pancreatic juice and bile are released through (intestine pancreatic/ hepato-pancreatic duct).
(f) Dipeptides, disaccharides and glycerides are broken down into simple substances in region of small intestines (jejunum/ duodenum).
Ans. (a) Absorption of amino acids and glycerol takes place in the small intestine.
(b) The faeces in the rectum initiate a neural reflex causing an urge for its removal.
(c) Skin and eyes turn yellow in liver infection.
(d) Rennin is a proteolytic enzyme found in infants gastric juice.
(e) Pancreatic juice and bile are released through hepato-pancreatic duct.
(f) Dipeptides, disaccharides and glycerides are broken down into simple substances in the region of small intestine called duodenum.
Question. Describe the enzymatic action on fats in the duodenum.
Ans. Fats are broken down by lipases with the help of bile into di and monoglycerides and further into fatty acids and glycerol in the duodenum The reaction involved in this process are as follows
Question. Name the part of the alimentary canal where major absorption of digested food takes place. What are the absorbed forms of different kinds of food materials?
Ans. Small intestine is the principle organ for the absorption of nutrients. The process of digestion complete here only and the final products of digestion are absorbed through the mucosa into the blood stream.
The absorbed form of different food materials are
Question. How is the intestinal mucosa protected from the acidic food entering from stomach?
Ans. The mucus secreted by the goblet cells along with the bicarbonates from the pancreas play an important role in lubrication and protection of the mucosal epithelium from
excoriation by the highly concentrated hydrochloric acid.
Long Answer Type Questions:
Question. What are the various enzymatic types of glandular secretions in our gut helping digestion of food? What is the nature of end products obtained after complete digestion of food?
Ans. Among various enzymatic secretions, gastric juice is released in stomach whereas the bile, pancreatic juice and the intestinal juice are the secretions released into the small intestine.
Pancreatic juice and bile are released through the hepato-pancreatic duct. Gastric juice contains hydrochloric acid and proenzyme – pepsinogen and prorennin. HCl maintains a strongly acidic pH which converst these proenzymes into pepsin and rennini (in infants) respectively. These enzymes act on proteins and convert them into simpler form, peptones.
The pancreatic juice contains inactive enzymes trypsinogen, chymotrypsinogen, procarboxypeptidases, amylases, lipases and nucleases.
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. The bile released into the duodenum contains bile pigments (billirubin and billiverdin), bile salts, cholesterol and phospholipids but no enzymes.
Bile helps in emulsification of fats, i.e., breaking down of the fats into very small micelles.
Bile also activates lipases. 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.
This juice contains a variety of enzymes like disaccharidases (e.g., maltase), dipeptidases, lipases, nucleosidases, etc. The mucus along with the bicarbonates from the pancreas protects the intestinal mucosa from acid as well as provide an alkaline medium (pH 7.8) for enzymatic activities. Sub-mucosal glands (Brunner’s glands) also help in this process.
Various reactions involved in this process are as follows
Question. Discuss mechanisms of absorption.
Ans. Mechanism of absorption for different molecules is as follow
(i) Small amounts of monosaccarides like glucose, amino acids and some electrolytes like chloride ions are generally absorbed by simple diffusion. The passage of these substances into the blood depends upon the concentration gradient
(ii) Fructose and some amino acids are absorbed with the help of carrier ions like Na+ . This mechanism of transport is called facilitated transport or active transport.
(iii) Transport of water depends on osmotic gradient.
(iv) Fatty acids and glycerol being insoluble, cannot be absorbed into the blood. They are first incorporated into micelles (smalll droplets) which move into intestinal mucosa.
Further, they are reformed into protein coated fat globules called chylomicrons which are transported to the lymph vessels in the villi. These lymph vessels ultimately release the absorbed substances into the blood stream.
Question. Explain the process of digestion in the buccal cavity with a note on the arrangement of teeth.
Ans. The buccal cavity performs two major functions i.e., mastication of food and facilitation of swallowing
Firstly, food gets mixed with saliva which softens and lubricates the food and cheuring process breaks the food into smaller pieces.
Buccal cavity is also involved in the digestion of same food components.
Digestion of carbohydrates starts in the buccal cavity. The food is mixed with saliva which contains salivary anylase. This enzyme converts starch into maltose, isomaltose and a −dextrins. 30% of the starch in food is hydorlysed in the buccal cavity.
Saliva do not any protein or fat digesting anzyme. Therefore, their digestion do not occur in the oral cavity.
The oral cavity has a number of teeth and a muscular tongue. Each tooth is embedded in a socket of jaw bone.
This type of attachement is called thecodont. The human have two sets of teeth a temporary and a permenant. This type of denotation is called diphyodont. The arrangement of teeth is illustrated below.
Question. A person had roti and dal for his lunch. Trace the changes in those during its passage through the alimentary canal.
Ans. 1. Digestion of Roti (Carbohydrates)
(a) Digestion of Carbohydrates in the Oral Cavity
In oral cavity, the roti is mixed with saliva. The saliva contains an enzyme salivary amylase (ptyalin) which converts starch in roti into maltose, isomaltose and small dextrins called α-dextrin. 30% of starch is hydrolysed in the oral cavity.
(b) Digestion of Carbohydrates in the Small Intestine The passage of party digested roti from oral cavity to oesophagus and then to stomach is regulated by peristalsis (the successive waves of muscular contraction in oesophagus). The stomach stores the food for 4-5 hours. The gastric juice does not contain carbohydrate digesting enzyme.
The partially digested food is now called as chyme. In intestine, following action occurs.
(i) Action of Pancreatic Juice Carbohydrates in the chyme are hydrolysed by pancreatic amylase into disaccharides.
(ii) Action of Intestinal Juice Intestinal juice contain maltase, isomaltase, sucrase (invertase), lactase and a-dextrinase.These enzymes act on food converting it into simpler compounds like glucose, fructose, galactose, etc.
2. Digestion of Protein
Proteins are made up of amino acids. So proteins are broken down to amino acid during the process of digestion.
Saliva does not contain any protein digesting enzyme. So, its digestion in stomach.
(a) Digestion of Protein in Stomach The stomach normally stores food for 4-5 hours.
The gastric glands of the stomach secrete gastric juice. It contains HCl, proenzymes like- pepsinogen and prorennin. Various reactions in stomach are discussed below
(b) Digestion of Protein in Small Intestine
(i) Action of Pancreatic Juice The enzymes trypsinogen, chymotrypsinogen and procarboxypeptidase in pancreatic juice are all concerned with the protein digestion.
Some reactions are given below
(ii) Action of Intestinal Juice Intestinal juice contain enzymes enterokinase, amino peptidase and dipeptidase and their actions are given below
The macromolecules that are broken down into simpler components are the products of roti and dal (carbohydrates and proteins) which are further absorbed by the villi in intestine and the rest undigested food is removed in the form of faeces.
Question. Discuss the role of hepato-pancreatic complex in digestion of carbohydrate, protein and fat components of food.
Ans. This bile duct (from gall bladder and liver) and the pancreatic duct (from pancreas) releases pancreatic juice and bile into the duodenum through the common hepato-pancreatic duct which is guarded by a sphincter called sphincter of Oddi.
The pancreatic juice contains inactive enzymes, i.e., trypsinogen, chymotrypsinogen, procarboxypeptidase, amylase, lipases and nucleases.
The action of hepato-pancreatic secretion on digestion on carbohydrate, proteins and fats are summarised below (i) Carbohydrates in the chyme are hydrolysed by pancreatic amylase into disaccharides.