Loading....
Coupon Accepted Successfully!

 

Question-1

What are enzymes?

Solution:
Enzymes are organic catalysts found in living organisms, which alter the fate of a chemical change, but remains unchanged themselves at the end of the reaction.

Question-2

What is the main function of the villi and microvilli?

Solution:
The main function of the villi and microvilli is to increase the absorptive area of the intestine.

Question-3

How is ingested fat absorbed in the body?

Solution:
Fat is absorbed in the small intestine. Bile salts secreted by the liver break down the bigger molecules of fat globules into smaller droplets. This process is known as emulsification. The enzyme lipase acts on emulsified fats and converts them into diglycerides and monoglycerides. In the end, the fats are converted into fatty acids, glycerol and monoglycerides.

Question-4

What is egestion?

Solution:
Egestion is passing out undigested food from the body.

Question-5

Name the enzyme secreted by the salivary glands of man.

Solution:
Saliva contains an enzyme ptyalin or salivary amylase, which acts upon starch and converts it into sugars.

Question-6

What is the function of teeth?

Solution:
The function of the teeth is to tear and crush food particles.

Question-7

You have eaten boiled rice for lunch. Make a list of enzymes that will act upon the rice and the changes it will undergo before being absorbed in the small intestine.

Solution:
Rice contains starch. The digestion of starch takes place in the mouth or buccal cavity. The saliva contains salivary amylase enzyme, which converts starch into maltose, isomaltose and dextrin. The pancreatic juice also contains amylase, which acts upon the starch and changes it into glucose and fructose. The intestinal juice also acts upon maltose, isomaltose and converts them into glucose.

Question-8

Where the taste buds are located?

Solution:
The taste buds are located on the tongue.

Question-9

Name the source of trypsin and the food constituent, which this enzyme hydrolyses.

Solution:
Pancreatic juice is the source of trypsin. It hydrolyses proteins into peptides.

Question-10

What is meant by digestion? Briefly describe the process of digestion of food in the small intestine of man.

Solution:
Digestion is a process in which complex food materials are broken down by enzymes into simpler substances, which can be easily assimilated by the body.

The process of digestion in the small intestine begins from the stomach. The pancreatic duct and bile duct open into the duodenum. Here the food gets mixed by bile juice and pancreatic juice. Bile juice does not contain any enzyme. However, it plays an important part in digestion as it provides an alkaline medium to food and helps in emulsification of fat. The pancreatic juice contains the following enzymes, which act upon different kinds of food stuffs.

(i) Trypsin, which acts on proteins and changes them to peptones.

(ii) Pancreatic amylase, which acts on carbohydrates and changes them to maltose or to other complex sugars.

(iii) Lipase, which acts on fats and changes them to soluble fatty acids and glycerol.
The intestinal glands secrete enzymes like,

1. Erepsin, which helps to convert peptides into amino acids.

2. Maltose, which changes maltose to glucose.

3. Lactose changes into glucose and

4. Sucrose changes into glucose.

In this way, the digestion of food is completed in the small intestine.

Question-11

Where gastric juice is found?

Solution:
Gastric juice is found in the stomach.

Question-12

What is intracellular digestion?

Solution:
Intracellular digestion is the digestion occurring with in the cell.

Question-13

How does coagulation of milk in the alimentary canal take place?

Solution:
When milk reaches the stomach, protein digestion starts. Pepsin stimulates the digestion of proteins in milk. HCl activates pepsinogen into pepsin. It hydrolyses soluble casein into paracasein to make solid curd, i.e., coagulation of milk. Renin, a milk coagulating enzyme is secreted as pro-renin, but in HCl it is hydrolysed into active rennin. Renin hydrolyses casein into paracasein leading to milk coagulation.

Question-14

Write the role of bile salts in the digestion and absorption of fats.

Solution:
Bile is secreted by the liver and is very important in the digestion of fats. It reduces the size of the fat globules. Smaller the size, larger the surface area of fat droplets and hence, greater the action of lipase. Bile juice also helps in the absorption of fats. Most of the water-soluble end products of fat digestion are actively absorbed from the intestine. But monoglycerides, diglycerides and fatty acids are insoluble in water. So they cannot be directly absorbed from the intestine. As a result of bile action, small droplets called micelles are formed. These micelles are absorbed into the intestinal walls.

Question-15

Which is the largest gland of the body?

Solution:
The largest gland of the body is liver.

Question-16

Differentiate between the large intestine and small intestine.

Solution:

Small intestine

Large intestine

(a) The small intestine is – 4.5 to 6 m in length. (a) The large intestine is only 1.5 m long.
(b) It does not have epiploic appendages. (b) Epiploic appendages are present.
(c) Digestion is completed in the small intestine. ( c) Large intestine plays no role in digestion.
(d) The small intestine secretes a number of hormones. (d) The large intestine does not secrete hormones.
(e) It absorbs the digested nutrients. (e) It takes part only in the absorption of water.
(f) Villi are present. (f) Villi are absent.
(g) Peyer’s patches are present in the small intestine. (g) Peyer’s patches are absent in the large intestine.
(h) Taeniae coli is absent. (h) Taeniae coli is present.
(i) Haustra are absent. (i) Haustra are present.
(j) The small intestine is narrow and 3.5 to 4.5 cm in width. (j) The large intestine is comparatively broader and 4.6 cm in diameter.
(k) The small intestine has three parts Duodenum, Jejunum and Ileum. (k) The large intestine has four parts Caecum, Colon, Rectum and Anus.
(l) Circular folds (Plicae circulares) are present in the small intestine. (l) Circular folds are absent in the large intestine.

 

Question-17

Can man digest cellulose?

Solution:
No, Man cannot digest cellulose.

Question-18

What are micelles?

Solution:
Monoglycerides, long chain fatty acids and digested fats unite with bile salts to form small spherical droplets known as micelles.

Question-19

How would it affect the digestion of proteins and carbohydrates in the duodenum of a man, if there is a blockade in the pancreatic duct? Explain.

Solution:
When there is a blockage in the pancreatic duct there will be non availability of pancreatic juice. The protease and amylase do not act on protein and carbohydrate in the duodenum. So digestion of proteins and carbohydrates in the duodenum of a man is not seen.

Question-20

What are the digestive fluids added to the food in the duodenum? What is their action?

Solution:
In the duodenum, pancreatic juice and bile juice are discharged by the pancreas and liver respectively. The pancreatic juice is secreted by pancreas and is brought to the duodenum with the help of pancreatic duct. Bile juice is secreted by liver cells. The pancreatic juice contains three enzymes, they are,

(i) Trypsin – It converts peptones into peptides and polypeptides.

(ii) Amylase – It converts all digestible polysaccharides to disaccharides.

(iii) Lipase – It converts fats to fatty acids and glycerol.

Question-21

How would non-secretion of saliva affect digestion of food in the mouth?

Solution:
Salivary amylase would not be able to digest starch or sugars.

Question-22

The wall of the alimentary canal has a thick layer of muscles. What is their function?

Solution:
The thick layers of muscles in the alimentary canal breaks the solid food into semi liquid food. It also facilitates the movement of food in the alimentary canal towards small intestine.

Question-23

How would non-secretion of hydrochloric acid in our stomach affect food digestion? Explain.

Solution:
(i) In the absence of HCl (Hydrochloric acid) pepsinogen is not activated and converted into pepsin.

(ii) Hence no protein digestion takes place.

(iii) It will not kill bacteria in the stomach (antiseptic action).

Question-24

Name any two proteases in the pancreatic juice. What are their specific roles?

Solution:
Chymotrypsin and trypsin are the two proteases in the pancreatic juice. They enable simultaneous stimulation of all pancreatic proteases for a very rapid digestion of proteins.

Question-25

Name the cells that secrete mucus. What are the functions of mucus?

Solution:
Goblet cells secrete mucus. They are found in mucosal epithelium and are called mucous glands.

Functions of mucus:

(i) Mucus acts as lubricant.

(ii) It protects the epithelial surface from excoriation and digestion.

(iii) It makes the food slippery also.

Question-26

Write short notes on ulcer.

Solution:
Under normal circumstances, the presence of HCl in the stomach does not harm the stomach epithelium as it remains protected by a layer of mucus secreted by the goblet cells. The mucus being slightly alkaline neutralizes the HCl. But in certain persons, these protective mechanisms are inadequate which leads to the erosions of the gastric or duodenal mucosa. These erosions are termed as ulcers. In some persons presence of parasites in the alimentary canal also causes ulcers.

Question-27

The muscular wall of the alimentary canal of man performs certain automatic movements which move the food forward. What these movements are known as?

Solution:
The muscular wall of the alimentary canal of man performs certain automatic movements, which move the food forward is called Peristaltic movements.

Question-28

The stomach of a patient had to be removed on medical grounds. What special diet would you recommend him and why?

Solution:
When the stomach of a patient is to be removed on medical grounds and the oesophagus is directly connected with the duodenum, the patient should be given simple diet in liquid form only. Milk is to be avoided because the curdling of milk takes placed only in the stomach. The food may consist of glucose, protein, carbohydrates all mixed together in the liquid form. No solids should be given to him. This liquid food should be such that it could be acted upon by intestinal juice.

Question-29

Where are salivary glands situated in man? What is their main function?

Solution:
In man the salivary glands are situated in the mouth. They contain starch-digesting enzymes. There are three pairs of salivary glands, parotids, sub maxillary and sublingual, which secrete saliva. The mucin in saliva helps to lubricate the food for swallowing. Its starch digesting enzyme ptyalin acts on the starch and converts it into maltose, isomaltose and limit dextrin in the alkaline medium.

Question-30

Name the digestive enzyme present in the saliva.

Solution:
Salivary amylase ptyalin is the digestive enzyme present in the saliva.

Question-31

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

Solution:
Salivary amylase is secreted in the buccal cavity and it digests starch and sugar. Since amylase does not act on proteins of which animal tissues are made of, it is secreted in its original form.

Trypsin acts on proteins. The wall of the alimentary canal is also made of proteins. Hence, it is very essential that it is secreted in an inactive form and it should become active when food proteins are available in the alimentary canal. Thus to prevent damage it is secreted in an inactive form.

Question-32

What is the name given to enzymes which hydrolyze proteins?

Solution:
The enzyme which hydrolyze proteins are proteases or peptidases.

Question-33

What is rennin?

Solution:
Rennin is milk-coagulating enzyme.

Question-34

In which medium does trypsin act best?

Solution:
Trypsin acts best in Alkaline pH.

Question-35

What is the function of chymotrypsin?

Solution:
The chymotrpin coagulates milk.

Question-36

What are the different parts of the small intestine in higher animals?

Solution:
Duodenum, jejunum and ileum are the different parts of the small intestine in higher animals.

Question-37

How many kilocalories of energy are produced on oxidation of 1 gram of food carbohydrate?

Solution:
4.2 Kilocalories of energy are produced on oxidation of 1 gram of food carbohydrate.

Question-38

How much food starch is hydrolysed in the mouth?

Solution:
About 30% of the food starch is hydrolysed in the mouth.

Question-39

What is the fuction of ptyalin?

Solution:
Ptyalin hydrolyses starch into maltose, isomaltose and ‘limit’dextrins.

Question-40

How does pepsinogen become active in stomach?

Solution:
Pepsinogen becomes active in stomach due to the presence of HCl.

Question-41

What is the function of pepsin?

Solution:
Pepsin hydrolyses soluble casein into paracasein.

Question-42

Name the enzyme, which causes the activation of pancreatic typsinogen.

Solution:
Enterokinase is the enzyme, which causes the activation of pancreatic trpsinogen.

Question-43

In which form is pepsin secreted?

Solution:
Pepsin is secreted in the inactive form of pepsinogen, which gets converted into pepsin by the acidic medium

Question-44

Name the milk-coagulating enzyme.

Solution:
Renin is the milk-coagulating enzyme.

Question-45

In which form is typsin secreted?

Solution:
In the inactive form of trypsinogen, which gets converted into trypsin in alkaline medium.

Question-46

In which medium does the enzyme trypsin act best?

Solution:
Alkaline medium is the medium in which the enzyme trypsin acts best.

Question-47

Mention the role of bile salts in the digestion of fats.

Solution:
Emulsification is the role of bile salts in the digestion of fats. Bile salts break large fat droplets into many smaller ones.

Question-48

Name the different parts of large intestine of humans in their natural sequence.

Solution:
Caecum, colon and rectum are the different parts of large intestine of humans in their natural sequence.

Question-49

Name the passage that leads bile from the liver into the gall bladder.

Solution:
Cystic duct is the passage that leads bile from the liver into the gall bladder.

Question-50

Can the trypsin hydrolyse casein for the coagulation of milk?

Solution:
No, the trypsin cannot hydrolyse casein for the coagulation of milk.

Question-51

What is the main function of bile salts?

Solution:
The bile salts reduces the surface tension of fat droplets causing their break down into many small ones.

Question-52

Name any animal starch.

Solution:
Glycogen is an animal starch.

Question-53

Name one function of saliva other than digestion.

Solution:
The mucin in saliva helps to lubricate the food for swallowing.

Question-54

On which side of the abdomen is the stomach found in human beings.

Solution:
The stomach lies on the left side of the abdomen in human beings.

Question-55

What is chylomicron?

Solution:
Chylomicron is the soluble fine globules of fat passing into the lacteals of villi.

Question-56

When is bile stored in gall bladder?

Solution:
The bile is stored in gall bladder when there is no food in the intestine.

Question-57

What does bile juice contain?

Solution:
Bile juice contains bile pigments and bile salts, but no enzyme.

Question-58

What is the advantage of emulsification of fats by bile juice?

Solution:
The advantage of emulsification of fats by bile juice are the large droplets of fat are broken into tiny droplets by bile juice to form an emulsion. The surface area of fat droplets is increased enabling lipase enzyme to digest fat.

Question-59

What is the function of the muscular wall of the stomach, other than secreting gastric juice?

Solution:
The muscular movement of stomach wall churns and mixes the food with gastric juice and propels it to the small intestine through the pyloric valve.

Question-60

What is the juice, that is carried by common bile duct and where?

Solution:
The common bile duct carries bile juice and pancreatic juice into duodenum.

Question-61

Name the different components of food.

Solution:
The different components of food are carbohydrates, proteins, fats, vitamins, water and minerals as well as roughage.

Question-62

Name the various types of salivary glands of man and their location.

Solution:
There are three of pairs of salivary glands in the mouth cavity. These are:

Parotid glands – These are present beneath each pinna.

Sub-mandibular – These are present at the junction of two jaws, one on each side.

Sublingual glands - These are present beneath the each tongue.

Question-63

Hydrochloric acid (HCl) and proteolytic enzymes produced by stomach do not digest its own wall, why?

Solution:
Hydrochloric acid (HCl) does not act on the wall on the stomach because the wall is covered by mucous, which forms a barrier. The proteolytic enzymes also do not reach the wall because of this factor.

Question-64

Differentiate between lipases and peptidases.

Solution:
Characteristics Lipases Peptidases
Solubility They are insoluble in water. They are soluble in water.
Substrate These hydrolyse fats and oils. These hydrolyse proteins, proteases, peptones and peptides.

 

Question-65

State the advantage of having villi in the intestinal wall.

Solution:
Intestinal villi: These are finger like projections that arise from the submucosa of small intestine. Each villus is lined by a single layer of simple columnar epithelium, which has absorbing cells and certain mucus cells, which are known as goblet cells. In each villus is present a capillary loop and small lymphatic vessel, the lacteal.

Villi increase the surface area of the small intestine, which comes in contact with digested food. Hence the absorption of digested food becomes easier and greater.

Question-66

How is food absorbed?

Solution:
The food eaten up by the individuals is in complex form. The various digestive glands present in the different parts of the alimentary canal discharge their enzymes. These enzymes under suitable conditions act upon the food. They break into the simpler nutrients, which are mostly water-soluble. The digested food consists of simple sugars, amino acids, fatty acids and glycerol etc.

The fatty acids and glycerol are absorbed through the intestinal wall through lacteals. The sugars, amino acids, salts and water are passed into the blood circulation. The absorption of water takes place mainly in the colon (large intestine). In the large intestine synthesis of vitamin B complex also takes place by certain bacteria present there.

Question-67

What is dental formula? What is the dental formula of man?

Solution:
The dental formula represents the number of teeth of specific types. The dental formula of man is

Question-68

How is the digested fat absorbed?

Solution:
Digested fat is absorbed in the small intestine. Bile salts break up bigger molecules of fat into small droplets called chylomicrons. The fat is absorbed in hydrolysed as well as in emulsified form. Fatty acids and glycerols are absorbed through the intestinal wall by the lacteals. Chylomicrons pass into the lacteals.

Question-69

Tyrpsin acts at an alkaline pH. What provides this alkalinity? Give two actions of trypsin.

Solution:
Trypsin acts best at an alkaline pH. In the small intestine bile (pH-8.0), pancreatic juice (pH-8.8) and intestinal juice (pH-8.3), act on chyme. Bile provides this alkalinity. Bile contains bicarbonates. They are also present in pancreatic juice.

Question-70

If there is a blockade in the pancreatic duct? How would it affect the digestion of protein.

Solution:
Pancreatic duct in addition to pancreatic juice brings bile juice also. The pancreatic juice contains many enzymes, which are as follows:

(a) Trypsin: It acts on protein, proteases and peptoses and converts them into amino acids.

(b) Amylopsin: It acts on starch and converts it into soluble sugars.

(c) Steapsin or lipase: It emulsifies the fats and converts them into fatty acids and glycerol. If there is a blockade in the pancreatic duct then there will be no digestion of proteins, fats and starch because the digestive enzymes will be absent.

Question-71

Why are many proteases released in an inactive form?

Solution:
The protein hydrolyzing enzymes are known as proteases. These proteases are secreted in inactive form and are called proenzymes. If these are secreted in active form these proenzymes would hydrolyze cellular and extra cellular proteins of the individual itself. Pepsin and Renin are secreted in active forms – pepsinogen and prorennin. These are activated at the sites of their action in stomach by optimal pH or by specific proteases.
Prorennin Rennin

Question-72

What is the role of micelles in the fat absorption?

Solution:
Role of micelles in fat digestion: During digestion, the fat in the intestine is converted to monoglycerides, diglecerides and fatty acids, which are insoluble in water. They cannot be directly absorbed from the intestinal contents. They are first incorporated into small, spherical and water-soluble droplets called micelles by bile salts. It is from these micelles that fatty acids, glycerides, sterols and fat-soluble vitamins are absorbed into the intestinal cells.

Question-73

What is the biological significance of E.coli in the intestine of man?

Solution:
Biological significance of E. Coli in the intestine of man: E. Coli is a symbiotic sbacterium. It takes up proteins in the intestine of man and breaks them into amino acids. Proteins are absorbed as amino acids in the intestinal villi. Vitamin B12K is synthesized by these bacteria. Bile pigments are changed into other degraded pigments, which impart colour to the faeces in man.

Question-74

How are the following enzymes activated in the alimentary canal? 

(a) Pepsin, 

(b) Carboxypeptidase, 

(c) Renin, 

(d) Trypsin, 

(e) Chymotrypsin.

Solution:
Pepsin. Pepsin became activated as soon as the food reaches the stomach i.e., as soon as the secretion of HCl takes place. In acts most effectively within the pH range of 1.6-3.2.

Carboxypeptidase. Enteropeptidase, which is present in intestinal juice, activates carboxypeptidase.

Rennin. It is secreted as prorennin, but HCl present in the gastric juice converts inactive prorennin into active rennin.

Trypsin and Chymotrypsin. These are inactive enzymes until they come in contact with enteropeptidase (intestinal enzyme), which converts them into active trypsin and chymotrypsin.

Question-75

Define the term absorption or assimilation of food.

Solution:
After the digestion, the next step is the absorption of the food by the wall of the intestine. In this process through the mucous membrane of the alimentary canal digested food in the liquid form gets absorbed and then passed on to the blood. To increase the absorptive area of the alimentary canal a large number of finger like processes richly supplied with blood vessels are present in all vertebrates.

Question-76

How many permanent teeth are present in human beings? Show with diagram.

Solution:
There are four types of permanent teeth found in human beings. There are incisors, canines, premolars and molars.

Question-77

Draw a well labeled diagram of VS. of mammalian tooth.

Solution:

Question-78

What is jaundice?

Solution:
In normal healthy individuals the plasma contains a small quantity of a bile pigment bilirubin produced in the liver. But when its level in the plasma increases, the skin and white portion of the eye and the mucous membranes are strained yellow. The condition is called Jaundice hepatitis. It is a disease of the liver caused by a virus Jaundice sometimes occurs in epidemic form when water gets contaminated.

Question-79

What is the role of enzymes in digestion?

Solution:
The various enzymes secreted by stomach, pancreas, and small intestine act on different kinds of food particles under certain conditions. The main function of the enzymes is to make the food particles (carbohydrates, proteins, fats) into assimilable form, so that ’food’ can be absorbed by the small intestine only if it is in simpler absorbable form.

Question-80

Some people can eat things even when standing on their heads. Why does not the food fall back into the mouth?

Solution:
There is a movement in the walls of oesophagus called peristaltic movement, which allows the food particles to move forwards i.e., towards stomach and not back. Thus food does not come back into mouth even at the time of standing on the head.

Question-81

Which digestive fluids are added to the food in the duodenum? What is their action?

Solution:
In the duodenum pancreatic juice and bile juice are discharged by the pancreas and liver respectively. The pancreatic juice is secreted by pancrease and is brought to the duodenum through pancreatic duct.

The pancreatic juice contains three enzymes: i.e., Trypsin, Amylase and Lipase.

Question-82

Distinguish between caloric value and physiological fuel value.

Solution:
Difference between caloric value and physiological fuel value:
 
Caloric value Physiological fuel value
Complete combustion of food nutrient under the laboratory conditions in the calorimeter is called caloric value. Complete combustion of food nutrient in the body under normal conditions is termed physiological fuel value.

 

Question-83

Write the difference between sucrase and maltase.

Solution:
Sucrase Maltase
Sucrase hydrolyses sucrose into glucose and fructose (monosaccharides). Maltase hydrolyses maltose into glucose (monosaccharides).

 

Question-84

Write the difference between diffusion and active absorption.

Solution:
Diffusion Active absorption
Diffusion is defined as the process of movement of molecules of gases, liquids or solutes from the regions of higher concentration to regions of lower concentration till the molecules are uniformly distributed throughout the available space. It is the process in which cells actively participate in absorbing a substance and have to perform work. It occurs more rapidly than diffusion. It can occur even when the concentration of a substance is much lower in the lumen than in the blood. By this process absorption of substance can be completed.

 

Question-85

Write the difference between lipase and peptidase.

Solution:
Lipase Peptidases
Lipase completes the digestion of fats to fatty acids and glycerol. Peptidases completes the digestion of protein by converting peptides and polypeptides to amino acids

 

Question-86

Write the difference between extra cellular digestion and intracellular digestion.

Solution:
Extra cellular digestion Intra cellular digestion
Where digestion of food takes place outside the cell with the help of enzymes and the products are then absorbed into the cell. E.g. higher animals. Where digestion of food takes place within the boundaries of a cell. E.g. Amoeba.

 

Question-87

Write three enzymes secreted by pancreas. Specify the substance and the product of each.

Solution:
Pancreas is a composite gland. It has exocrine and endocrine parts. The exocrine part secrets pancreatic juice. It contains trypsin, amylopsin and steapsin.

(a) Trypsin. It converts proteins, peptones and proteases into amino acids.

(b) Amylopsin. It acts upon starch and converts them into soluble sugars.

(c) Steapsin or lipase. It emulsifies fats and converts them into fatty acids and glycerol.
Insulin a hormone is also produced in the pancreas (Islets of Langerhans). It controls the rate of gulcose metabolism and the level of glycogen in the blood.
Its deficiency results in a disease known as diabetes.

Question-88

Explain the structure of liver. What is its role in body?

Solution:
Liver. The liver is a compact reddish brown structure, which is situated in the anterior region of the body. Between the two lobes of the liver is situated a thin walled round sac like structure called the gall bladder. In this sac, bile secreted by liver cells is stored. From the liver the bile passes into the gall bladder through small ducts the hepatic duct. A duct for the cystic duct continues onward to the duodenum as common bile duct.

Functions of Liver:

(a) The liver secretes bluish or greenish bile juice.

(b) It contains liver salts like sodium carbonate and cholesterol.

(c) The bile is a bitter alkaline fluid. It contains about 90% of water.

(d) It contains products of decompositions by haemoglobin or the red blood corpuscles.

(e) The bile juice is alkaline. It turns the medium of the food from acidic to alkaline because in the alkaline medium further digestion can take place.

(f) The bile reduces the action of gastric juice in the ileum and prepares the chyme for the action of pancreatic juice.

(g) The bile juice contains biliviridin and bilirubin and bile salts, water and their excretory material.

(h) It (bile) also acts as an antiseptic and kills the bacteria and germs.

(i) The liver acts as a store house for non-consumable sugar, which is stored in the form of glycogen. At the time of need the glycogen is converted into glucose.

(j) Glycogen is synthesised from proteins.

(k) Proteins and amino acids converted into urea, is the excretory product.

(l) The kupffer cells of liver pick up the fat granules and change them into ordinary fat.

(m) Vitamin A, D, iron and copper are stored in the liver.

(n) The special blood cells destroy and eat bacteria.

(o) Heparin produced by it helps in the clotting of blood.

(p) The excretory products produced elsewhere in the body are neutralized in the liver.

(q) The toxic substance are converted into non-toxic substances.

Bile Juice - Bile juice is secreted by the liver. It has no enzymes. It has certain bile salts. It performs the following functions:

a. It neutralizes the acidity of the food and makes it alkaline.

b. It prepares food for the action of pancreatic juice.

c. It avoids putrefaction.

d. It emulsifies fat.

It helps in the absorption of fats by combining with it soluble substances like cholesterol to form water-soluble complexes, which can be more easily absorbed.

Question-89

Write a brief note on physical and mechanical digestion.

Solution:
In mechanical digestion the food is broken down to smaller pieces. Mastication occurs in the mouth and the buccal cavity. Deglutition is common process in the pharynx and the oesophagus. Peristalsis occurs in oesophagus, stomach and colon.

Swallowing is done in pharynx and movement of food mass is seen in every part of the alimentary canal. Churning movement is produced in stomach, as well as in intestine.

Question-90

If the pancreatic ducts of a person were blocked, how would it affect the digestion of fats in the duodenum?

Solution:
Pancreatic duct in addition to bringing pancreatic juice brings bile juice also (a) The pancreatic juice contains enzymes, which digest fats, (b) The bile juice helps in the emulsification of fats. In the absence of these, the digestion of fats is seriously affected.

Question-91

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

Solution:
Juice, enzymes their substrates and products:

Juices

Enzymes

Substrates

Products

1. Gastric Juice Pepsin
Rennin
Proteins, casein (milk)
Casein
Peptones, Paracasein (curd) 
Paracasein
2. Pancreatic Juice Trypsin (i) Proteins (i) Peptides
    (ii) Chymotrysinogen (inactive) (ii) Chymotrypsin (active)
    (iii) Procarboxy Petidases (inactive) (iii) Carboxy peptidases (active)
    (iv) Protelactase (inactive) (iv) Elastase (active)
    (v) Fibrinogen (blood) (v) Fibrin (clot)
  Chymotrypsin
Carboxypeptidases
Casein
Peptides
Paracasein
Small Peptides, amino acids
3. Intestinal Juice Enterokinase Trypsinogen (inactive)
Peptides
Trypsin (active)
Small peptides, amino acids.
  Dipeptiases Dipeptides Amino acids.

Question-92

If a major part of the small intestine of mammals were removed, will this affect absorption of food?

Solution:
The major part of the food is absorbed only in the small intestine. Only some part of water is absorbed in the stomach. So, if the major part of the small intestine is remove it would seriously affect the absorption of digested food.

Question-93

What digestive disorders do you expect in a habitual alcoholic?

Solution:
Alcoholic is a person who consumes lots of alcohol regularly. Alcohol is directly absorbed from the stomach by the blood capillaries. The alcohol is known to cause damage to the liver cells. Liver cells produce bile juice. If the liver cells are damaged they would not be able to produce bile. If the bile is not produced in required quantities, the emulsification and further digestion of fats is not possible. This would bring about disturbances in the digestion and adsorption of fats. The alcohol also hardens the stomach wall, which would reduce the churning of food in the stomach.

Question-94

Describe the alimentary canal of man.

Solution:
Alimentary Canal of man. The alimentary canal of man is a long coiled tube of varying diameter. It measures from 8 to 10 meters in length. It is divided into the following parts:

(a) Oral cavity

(b) Pharynx

(c) Oesophagus

(d) Stomach

(e) Small intestine

(f) Large intestine.

(a) Oral cavity. It is the initial enlarged part of the alimentary canal. It opens at the mouth and consists of lips, cheeks, gums, teeth and the palate and its muscles. The salivary glands open in the oral cavity.

(b) Pharynx. The oral cavity passes into pharynx.

(c) Oesophagus. It is muscular tube some10 inches long through which food passes into the stomach where it joins the cardiac stomach.

(d) Stomach. The stomach is a sac like structure and situated below the diaphragm. The wall of the stomach contains many small gastric pits into which ducts of gastric glands open.

(e) Small intestine. It is a long tube like structure measuring about 5-7 metres. It is divisible into 3 parts namely the duodenum, the jejunum and the ileum. The duodenum is the first part and U shaped. In this open the opening of pancreatic duct and bile duct.

(f) Large Intestine. The large intestine is about 1.5m long. It consists of caecum with vermiform appendix, colon and rectum. The rectum opens to the exterior by anus.

Question-95

Differentiate between duodenum, jejunum and ileum.

Solution:

Duodenum

Jejunum

Ileum

1. Anterior part of the small intestine. Middle part of the small intestine. Terminal part of the small intestine.
2. Broad leaf like ridges Rounded or tongue shaped. Narrow, finger or club shaped.
3. Brunner’s glands
present.
Brunner’s glands absent. Glands absent.
4. Peyer’s patches absent. Peyer’s patches absent. Peyer’s patches are present.
5. Plicae circulars are less in number. Plicae circulars are abundant in number. Circular folds are moderate number.
6. The wall is thin. The wall is thick. The wall is comparatively thinner.
7. The Villi occur in sufficient number. The Villi are abundant in number. The Villi are fewer in the distal part, but in good number in the proximal part.
8. Curved (U-shaped), and uncoiled. Bit coiled and longer. More coiled and much longer.
9. Length is 20-25cm. Length is 1.8-2.4m. Length is 7m.
10. It is 4.5 cm in diameter 4.0 cm in diameter. 2-3 cm in diameter.

 

Question-96

How is the DNA content in our diet digested in the body?

Solution:
Digestion of DNA content in our body.
DNA content is digested in the intestinal part of our alimentary canal by the enzymes present in pancreatic juice and succus entericus.

Question-97

Describe coagulation of milk in the alimentary canal.

Solution:
Coagulation of milk in the alimentary canal: When the food or milk reaches stomach, the protein digestion starts. Pepsin stimulates the digestion of proteins in milk (casein). HCl activates pepsinogen into pepsin. It hydrolyses soluble casein into paracasein, which is precipitated as calcium paracaseinate to make solid curd i.e., coagulation of milk. There is milk-coagulating enzyme called rennin, which is found in calf gastric juice. Rennin is secreted as pro-rennin (inactive state), but in +cardiac exam of HCl it is hydrolysed into active rennin. Rennin hydrolyses casein into paracasein leading to milk coagulation.

Question-98

Explain the digestion of fats in the intestine.

Solution:
Digestion of fats in the intestine: Lipases are enzymes for hydrolyzing fats and oils. Lipase converts fats to fatty acids and glycerol. Lipases are water soluble while fats and oils are insoluble in water and they form emulsions in aqueous media. Therefore lipase acts only on the water-adjoining surface of fat droplets. Lipase is present in pancreatic juice and intestinal juice only. Pancreatic lipase hydrolyses triglycerides into diglycerides and monoglycerides while as intestinal base converts diglycerides to monoglycerides and glycerol releasing fatty acids reach step. So monoglycerides glycerol and fatty acids are the major products and digestion.

Bile juice also helps in fat digestion. It reduces the size of the fat globules, the smaller the size, larger the surface area of the fat globules, greater action and lipase.

Question-99

Describe the digestion of starch in alimentary canal.

Solution:
Digestion of starch in alimentary canal: In man and most of the other mammals digestion starts in the mouth or buccal cavity. There are three pairs of salivary glands present in the mouth. These glands secrete an alkaline fluid saliva. The crushed food is mixed with the saliva and is converted into a pulpy mass called bolus. The saliva contains enzyme ptyalin (salivary amylase), which acts on cooked starches (polysaccharides) changing them to the disaccharide maltose. Optimum pH for this reaction is 6.7. As soon as the food reaches the stomach the action of ptyalin stops because of the acid reaction of gastric juice (pH 1.5 to 1.8) and the stomach contents entering the duodenum are now called as chyme. When acid chyme passes into the small intestine it is mixed first with the pancreatic juice and bile and then with the intestinal juice.

Pancreatic juice contains enzyme amylase, which converts all digestible polysaccharides (starches) not affected by ptylin to disaccharides (sugars). Intestinal juice also contains amylase, sucrose, maltase and lactase. These enzymes convert disaccharide into monosaccharide and hence digestions of starch is complete.

Question-100

Explain the role of bile salts in the digestion and absorption of fats.

Solution:
Role of bile salts in the digestion and absorption of fats: Bile juice is secreted by the liver and is very important in the digestion of fats. It reduces the size of the fat globules, smaller the size larger the surface area of fat droplets, the greater the action of lipase. Bile juice also helps in the absorption of fats. Most of the water soluble end products of fat digestion are actively absorbed from the intestine. , But monoglycerides, diglycerides and fatty acids are insoluble in water so they cannot be directly absorbed from the intestine. So first of all small droplets called micelles. i.e., (these monoglycerides, diglycerides and fatty acids are first incorporated into droplets of water with the help of bile salts) are formed. Then these micelles are absorbed into the intestinal walls.

Question-101

What are essential amino acids?

Solution:
Essential amino acids: Some amino acids cannot be synthesized in the animal body and are supplied with food in adequate amount from the outside sources. Such amino acids are called as essential amino acids. They are vital for the maintenance of the body e.g. Milk, meat, egg contains the essential amino acids.

Question-102

Draw a diagram of human alimentary canal starting from stomach and ending at anus. Label any five parts.

Solution:

Question-103

Name any one enzyme that coagulates milk protein in a human adult. Mention the source and site of action of that enzyme and the products formed.

Solution:
A Human adult instead of human.

Question-104

Describe the histology of gut in man.

Solution:
The wall of alimentary canal has 4 different layers viz. mucosa, submucosa, muscularis externa and serosa. Different types of cells form these layers:

(i) Mucosa: It is innermost layer having secretory and absorptive cells. It is moist and friction resistant. It has villi.

(ii) Submucosa: It lies outside the mucosa cells. It consists of soft connective tissue and blood as well as nerve supply and lymph vessels.

(iii) Muscularis externa: It lies outside the submucosa. It is made of circular inner layer and longitudinal outer layer of smooth muscles.

(iv) Serosa: It is outermost layer of gut. It is a fibrous coat.

Question-105

Which is the largest gland of the body?

Solution:
Liver

Question-106

Name the fully digested food present in the intestine?

Solution:
Chyle.

Question-107

Name the two bile pigments found in the bile.

Solution:
Bilirubin and Biliviridin.

Question-108

Give one reason as to why many of the intestinal proteases are secreted in inactive form?

Solution:
To protect the intestinal mucosa from auto digestion, most of the proteases are activated only after they are released.

Question-109

How does saliva act in self defence?

Solution:
Saliva has lysozyme which kills the bacteria by lysing their cell wall.

Question-110

Mention any two functions of hydrochloric acid in gastric juice?

Solution:
(i) HCl activates the pepsinogen and prorenin and provides acidic medium for the action of pepsin.

Question-111

Name the secretions of

(a) Goblet cells

(b) parietal cells.

Solution:
(a) Goblet cells – mucus

(b) parietal cells – HCl

Question-112

What are microvilli. State their functions.

Solution:
(i) Microvilli are finger like projections of the mucosa of intestine

(ii) They increase the surface area of digestion and absorption

Question-113

Name the various types of salivary glands of man and mention their location?

Solution:
There are three pairs of salivary glands in man. They are

(a) parotid- These are present beneath each pinnae

(b) sub-mandibular-present at the junction of to jaws, one on each side

(c) Sublingual –present beneath the tongue




Test Your Skills Now!
Take a Quiz now
Reviewer Name