Monday, 28 April 2014

TEXTBOOK ANSWERS AND SOLUTIONS Chapter-16-Digestion and Absorption CBSE-CLASS-XI-BIOLOGY




1)  Choose the correct answer among the following:
     a) Gastric juice contains
          I) pepsin, lipase, rennin
          ii) Trypsin, lipase, rennin
          iii) Trypsin, pepsin, lipase
          iv) Trypsin, pepsin, rennin

     An- Pepsin, lipase, rennin

     b) Succuss entericus is the name given to
          I) a junction between ileum & large Intestine
          ii) Intestinal juice
          iii) Swelling in the gut
          iv) Appendix

     Ans. – ii) Intestinal juice

2)  Match the following

          Column-I                     Column-II

     A) Billirubin & Biliverdin                 I) Parotid
     b) Hydrolysis of starch                    ii) Bill
     c) Digestion of fat                        iii) Lipases
     d) Salivary gland                     IV) Amylases

          An- {a – iii}          {c – iii}
               {b – Iv)     {d – i)


3) A) Why are villi present in the intestine & not in stomach?

     To increase the surface area of the intestine for the efficient absorption of digested food villi are present in intestine.

     b) How does pepsinogen changes into its active form?

     Pepsin (inactive form) is first changed by HCL into active enzyme pepsin. Then through autocatalysis more of pepsinogens get activated to pepsin.

     c) What are the basic layers of the wall of the alimentary cannot?

     The four main concentrate coats of alimentary canals are
          I) visceral peritoneum
          ii) Muscular coat
          iii) Sub – mucosa
          iv) Mucosa

     d) How does bile help in the digestion of fats?

          Fats are broken down by lipase with the help of bill into di- and monoglycerydes

          Fats is passes Diglycerides – monoglycerides

4) Give the teeth formula of human beings
    
          =

5) Describe the digestive role of chymotrypsin. Which two others digestive enzymes of the same category are secreted by its source gland?

Chymotrypsin converts; proteins into large peptides, Trypsin &   Elastase are two other digestive enzymes of the same category are secreted by its source gland.

6)   How are polysaccharides & disaccharides digested?

          Digestions of polysaccharides

     Action of saliva starch maltose + Isomaltose + alpha dextrin

     Action of Pancreatic Juice

          Starch  Maltose + Isomaltose + alpha-Dextrin

          Digestion of Disaccharides
          Action of Intestinal Juice

          Maltose   Maltose    Glucose + Glucose
          Isomaltose    Isomaltose    Glucose + Glucose
          Sucrose     sucrase         Glucose + fructose
          Lactose lactase Glucose + Galactose
          Dextrin Dixtrinose Glucose

7)   What would happen if HCL is not secreted in the stomach?

     Pepsinogen (proenzyme) & prorenin (pro-enzyme) will not be concentrated into pepsin & rein respectively. Hcl provides acidic medium so that the enzyme can act on food in stomach. Hcl kills bacteria & other harmful organism that may be present along with food.

8)   Explain the term thecodont & diphyodont?
     In human beings, teeth are embedded in pits, the sockets of the jaw bones. Such teeth are called thecodont.

     The teeth that appear in two sets i.e. milk teeth which are latter replaced by permanent teeth. This condition is called diphycodont.

9)   Name different types of teeth their no in an adult human.

     Upper jaw          lower jaw               upper jaw          lower jaw
Incisors 4          4       Premolars        4            4
Canines   2           2       molars      6             6

10) State the role of pancreatic juice in digestion of proteins

     Action of pancreatic juice – pancreatic juice contains pro-enzymes
     Trypsinogen, chymotrypsinogen and procarboxypeptase
     And enzyme elastase

          Tripsinogen trypnin
          (Proenzyme)

          Chymotrypsin Trypsin Carboxypeptidase
          (Pro-enzyme)

     Pretium 1 peptones & proteases are acted upon as given below

          Proteins Trypsin Dipeptides
          Peptones Chymotrypsin Dipeptides
          Proteases Carboxypeptidases Dipeptides
          Pro-elastase Typsin Elastase
          (Pro-enzyme)
         

11) Describe the process of digestion of protein in stomach.

          The digestion of proteins in stomach is caused by the actions of gastric juice. The stomach contains Hcl, proenzymes – pepsinogen & prorenin. Hcl mainly maintains a strong ph balance of body about 1.5 to 2.5 in the stomach. They kill the bacteria entering with food .hcl converts pepsinogen and prorenin into pepsin and rennin. Once pepsin is formed it changes pepsinogen into pepsin. Such activation is called autocatalytic reaction. Pepsin and rennin are absent in invertebrates’. Gastric juice is thoroughly mixed with food until it becomes a semi fluid mass called chyme

12) Bite juice contains no digestive enzyme yes it is important for digestion why?

     Bite contains no digestive enzyme yet it is important for digestion. Why?
1. Neutrilises hcl
2. Emulsification
3. Activate lipase
4. Absorption of fats and fat soluble vitamins


13) How does butter in your food get digested & absorbed in the body?

     Term lipase is usually used as fat digestive enzyme

     Saliva contains no lipase. The stomach also lacks much fat emulsifying agent. However the gastric juice contains small amount of gastric lipase active some fat into mono glycerides & fatty acids. That is largely digested on small intestine. But bile break down fat droplets into may small ones by reducing the surface areas of fat droplets. This process is called emulsification. & increase lipase action on fat. Pancreatic lipase to the principal enzyme for the digestion of fat. In addition intestinal lipase in also helpful in digestion of fat

     Fat   Bite   emulsified
     (Triglyceride)

14) Discuss the main steps in the digestion of proteins as the food posses through different parts of canal.

          Digestion of proteins occurs by
1) Digestion in the stomach
2) Digestion in the small intestine.
1) Action of pancreatic juice
2) Action of intestine Juice

15) What are the functions of liver?
    
1) Production of bill    ii) Deamination
     iii) Excretion          IV) Neutralization of Hcl.
     v) Lymph formatives.
     vi) Destruction of R.B.C
     vii) Secretions of enzymes
     viii) Glycogenesis. 
Written By Badal Paul
The author is a passionate blogger, writer and educationalist. This blog is created to ease troubles of the Cbse students. The author holds multiple blogs and the writer of the Novel KALCHAKRA, OOM AND THE CHOSEN FIVE.