1. Nutrition:  The process of taking nutrients or molecules required for the growth and development of body and to obtain energy is known as nutrition.
2. Nutrients:  The components of food that are necessary for growth, maintenance and repairing damage parts etc. are called nutrients.
3. Digestion: The process of breakdown of complex components of food into simpler substances is called digestion.
4. Digestive system: The alimentary canal and the associated glands togetherconstitute the digestive system.
5. Ingestion: To take food gets through mouth is called ingestion.
6. Absorption: The digested food gets absorbed by the wall of small intestine andpass into the vessels, this process is called absorption.
7. Assimilation: The process of absorption is followed by the distribution of absorbed food to all parts of the body---is called as assimilation.
8. Egestion: The faecal matter is removed through the anus from time to time is called egestion.
9. Rumen: Guess eating animals quickly swallow the grass and store in a separate part of the stomach is called rumen.
10. Cud: The partially digested food in rumen is called cud.
11. Rumination: A process in which partially digested food (cud) returns to the mouth in small lumps and the animal chews it, such type of process is called rumination, and such type of animals are calledruminants.
 12. Cellulose: A type of carbohydrate. Many animals including humans cannot digest cellulose, because they lacks cellulose digesting enzyme.
13. Pseudopodia: Amoeba constantly change the shape and position. It pushes out one or more finger like projections are called pseudopodia.
 14. Human digestive system: The human digestive system consists of the alimentary canal and necessary glands.

                         The alimentary canal can be divided into various components:

      (a)  Buccal cavity
       (b)  Oesphagus
       (c)  Stomach
       (d)  Small intestine
       (e)  Large intestine
       (f)   Anus
       The main digestive glands which secrete digestive juices are:
       (a)  Salivary gland
       (b)  Liver
       (c)  Pancreas.
15. Buccal cavity: It is the part of alimentary canal. In buccal cavity, saliva which is secreted by salivary glands is mixed with the food. Here, food enters in the food pipe and through the food pipe goes to the stomach.
16. Food vacuole:  When a food particle comes in contact with the boy of the amoeba its cell gives out projections to surround the food particle. The food is engulfed and taken in the cell, forming a food vacuole. Digestive juices are secreted into the food vacuole.
17. Teeth: Teeth in man are present in both the jaws and embedded in the sockets of the jaw bones. They develop in two set.
        i) Milk or deciduous teeth.
       ii)  Permanent or successional teeth.
         Milk teeth are smaller, weaker and temporary. They are replaced by permanent teeth    between 6-12 years. They are 20 in number. 10 in each jaw. There are four types of teeth:
Incisors: There are four teeth in front of the mouth which help in biting and cutting the food materials.         
           (b) Cannines: There are two teeth one on each side of the incisors, which help in tearing the food materials.  
           (c) Premolars:  There are four teeth. Two premolars on each side of the jaw which help in crushing the chewed food materials.
           (d) Molars: There are six teeth. Three on each side of the jaw and just behind the premolars which help in grinding the food materials.

                                      Fig. 2.1. Arrangement of different types of teeth
18. Salivary glands: Salivary glands are a pair of small and branched structures situated in the mouth cavity. Their secretion is known as saliva which contains starch splitting enzyme namely amylase and mucin for easy swallowing of food.
      The saliva breaks down the starch into sugars.
19.  Saliva:  It is a secretion which contains starch splitting enzyme for easy swallowing of food.
20.  Tongue: Tongue is a voluntary, glandular and muscular structure found on the floor of the mouth. It helps in swallowing and tasting the food. It is also essential for creating a distinct speech mastication and mucus secretion.

Fig. 2.2. Regions of the tongue for different testes 
21.  Oesophagus: It is a ling, narrow, muscular tube which directly leads to the stomach. It is about 25 cm long and passes downwards through the neck, the thorax and the abdominal cavity.

                                                                   Fig. 2.3. Movement of the food in the alimentary canal
22.  Stomach: Stomach is a thick walled bag. Its shape is like a flattened U and it is the widest part of the alimentary canal. Stomach receives food from the food pipe at one end and open into the small intestine.
23.  Small intestine: The small intestine is highly coiled and is about 7.5 meters long. It consists of three parts:
  1. Duodenum
  2. Jejunum
  3. Ileum
It receives secretions from the liver and the pancreas. The wall of small intestine contains gland for enzyme secretion and villi/microvilli for absorption of food.
24.  Liver: The liver is the largest organ in the body. It weighs between 1-2 kgs. It is a reddish brown gland situated in the upper part of the abdomen on the right side. Liver secretesbile juice.
25.  Gall bladder: This is a pear-shaped sac, with a capacity of approximately 60 ml of bite juice, i.e., attached to the under surface of the right lobe of the liver.
26.  Bile juice: Liver secretes bile, which is temporarily stored in the gall bladder. The bile plays an important role in the digestion of fats.
27. Amino acid: It is a carboxylic acid that contains the amino group. These acids are the unit that link together and form proteins.
28.  Amoeba: A microscopic single-celled organism is called amoeba. It is found in pond water.
29.  Fatty acids: An organic compound consisting of a long hydrocarbon chain and a terminal carboxylic acid.
30.  Glycerol: It is a colourless sweet-tasting viscous liquid, miscible with water. It is widely distributed in all living organism as a constituent of the glycerides.
31.  Pancreas: Pancreas is a large cream coloured gland located just below the stomach. The pancreatic juice acts on carbohydrates and protein and changes them into simpler forms.
32.  Villi: The inner walls of the small intestine have thousand of finger-like outgrowths are called villi.
33. Large intestine: The large intestine is wider and shorter than small intestine. It is about 1.5 metre in length. Its function is to absorb water and some salts from the undigested food material. It consists of three parts:
      (a)  Caecum
      (b)  Colon
      (c)   Rectum.

      Digestion of carbohydrates,  like starch begins in the buccal cavity.
Table  2.1. Digestive Enzymes: source, affects and resultant products.

Resultant  Products
Salivary glands
Gastric glands
Peptides and amino acids
Pancreatic juice
Trypsin, Carboxy- peptidase, Amylase, Lipase 
Glucose and other simple Sugars
Q. 1. Fill in the blanks:
         (a)  The main steps of nutrition in humans are ………….., …………..,
                 ………., …………..  and  ………… .
         (b)  The largest gland in the human body is ………….. .
         (c)  The stomach release hydrochloric acid and ………… juices which act on food.
         (d)  The inner wall of the small intestine has many finger-like outgrowths
                Called ………….. .
         (e)  Amoeba digests its food I the ………….. .
Ans.  (a)  ingestion, digestion, absorption, assimilation and egestion.
          (b) liver
          (c) digestive
          (d) villi
          (e) food vacuole
Q. 2. Mark ‘T’ if the statement is true and ‘F’ if it is false:

Digestion of starch starts in the stomach. (T / F)
         (b)  The tongue helps in mixing food with saliva. (T / F)
         (c)  The gall bladder temporarily stores bile. (T / F)
         (d)  The ruminants bring back swallowed grass into their mouth and chew it for some time. (T/ F)
Ans.     (a) F                     (b) T                     (c) T                      (d) T  
Q. 3. Tick ( v ) mark the correct answer in each of the following:
         (a)  Fat is completely digested in the
                (i) stomach                                  (ii) mouth
              (iii) small intestine                       (iv) large intestine
         (b)  Water from the undigested food is absorbed mainly in the
                 (i) stomach                                  (ii) foodpipe
                (iii) small intestine                      (iv) large intestine
Ans.    (a)   (iii) Small intestine
            (b)  (iv) Large intestine.
Q. 4.  Match the items of Column I with those given in Column II:
           Column I                                            Column II

           Food Components                              Product(s) of digestion
           Carbohydrates                                    Fatty acids and glycerol
           Proteins                                              Sugar
           Fats                                                     Amino acids
Ans.    Column I                                           Column II
            Food Components                             Product(s) of digestion
            Carbohydrates                                   Sugar
            Proteins                                             Amino acids
            Fats                                                   Fatty acids and glycerol
Q. 5.  What are villi? What is their location and function?

The inner walls of the small intestine have thousand of finger-like outgrowths, these are called villi.

          Function of Villi:

          The villi increase the surface area for absorption of the digested food.
Q. 6.  Where is the bile produced? Which component of the food does it help to digest?

Bile is produced in liver. The bile juice stored in a sac called the gall bladder. The bile plays an important role in he digestion of fats. 
Q. 7.  Name the type of carbohydrate that can be digested by ruminants but not by humans. Give the reason also.

Cellulose is the carbohydrate that can be digested by ruminants. Ruminants have large sac like structure between the small intestine and large intestine. The cellulose of the food is digested by the action of certain bacteria which are not present in humans.
Q. 8. Why do we get instant energy from glucose?

Because glucose can easily breakdown in the cell with the help of oxygen and gives carbon dioxide, water and energy.
Q. 9.  Which part of the digestive canal is involved in:
absorption of food ……………. .
             (ii) chewing of food ……………… .
            (iii) killing of bacteria …………….. .
            (iv) complete digestion of food ……………… .
             (v) formation of faeces ………………. .
Ans.     (i) Small intestine                                     (ii) Mouth
            (iii) Stomach                                            (iv) Small intestine
             (v) Large intestine
Q. 10. Write one similarly and one differences between the nutrition in amoeba and human beings.

Ans.    Differences:

            Similarly: During the digestion of food, amoeba secretes digestive juices into the food vacuole. They act on the food and break it down to simpler substances. In case of human being, the inner walls of stomach and the      small intestine also secrete the digestive juices. The digestive juices convert complex substances of food to simpler ones.
            Amoeba: Amoeba feeds some microscopic organisms. When it senses food, it pushes out pseudopodia around the food particle. The food trapped in a food vacuole.
            Human beings: We take food through the mouth, digest and utilize it. The food component gradually get digested as food travels through the various compartment.
Q. 11. Match the items of Columns I with suitable items in ColumnII
                Column I                                                 Column II

           (a)  Salivary gland                              (i)   Bile juice secretion
           (b)  Stomach                                       (ii)  Storage of undigested food
           (c)  Liver                                            (iii)  Saliva secretion
           (d)  Rectum                                        (iv)  Acid release
           (e)  Small intestine                             (v)   Digestion is completed
           (f)  Large intestine                             (vi)   Absorption of water
                                                                      (vii)  Release of faces

Ans.          Column I                                                 Column II

           (a)  Salivary gland                              (iii)  Saliva secretion
            (b)  Stomach                                        (iv) Acid release
            (c)  Liver                                               (i)  Bile juice secretion                         
            (d)  Rectum                                          (ii)  Storage of undigested food
            (e)  Small intestine                               (v)  Digestion is completed
            (f)  Large intestine                               (vi) Absorption of water.
 Q. 12. Label Fig. 2.4 of the following system.
                                                               Fig. 2.4. Part of human digestive system

Q. 13. Can we survive only on raw, leafy vegetables/grass? Discuss.

We know that the heterotrophs do not possess the ability to synthesise their own food. Therefore, they depend upon autotrophs for their food supply either directly or indirectly. We also know that the green plant (leafy vegetables/grass) trap solar energy manufacture their food in the form of glucose. So we say leafy vegetable and grass can provide the sufficient energy for human being to survive.

Q.1. Give
one word for the following:
The organisms which synthesise their own food.

Q.2 Give oneinstant source of carbohydrate.

Q.3. What are the constituents of food?

Proteins, fats, carbohydrates, vitamin and minerals.
Q.4. What is nutrition?

Ans. The mode of taking food by an organism and its utilization by the body is called nutrition.
Q. 5. What is digestion?

The food we eat is chewed and broken down into smaller particles and then converts its component in liquid form which gets absorbed. This process is called digestion.

Q. 6. Name various digestive organs of man.

The organs which carry out digestion and absorption of food are the digestive organs. Mouth, oesophagus, stomach, small intestine are the digestive organs of man.
Q. 7. Where does the digestion start?

Digestion of food starts in mouth, continues in the stomach and is completed in the duodenum and small intestine.
Q. 8. What is the nutrient in autotrophic plants?

In autotrophic plants, the process of photosynthesis is referred to as nutrition.
Q. 9. What are the two life processes?

Living organisms require energy for all the life processes for the continuation of its species. The energy is obtained with the help of two main processes:

          (1)  Nutrition     (2) Respiration.
Q. 10. What is salivary digestion?

The food we eat is chewed by the teeth and mixed with saliva. Saliva contains an enzyme called ptyalin which digest carbohydrate present in the food. It is due to saliva, the bread tastes sweet after chewing. Saliva is secreted by salivary glands present in mouth. This type of digestion of food by saliva is called salivary digestion.
Q. 11. Describe the process of absorption and transportation of water and minerals in plants.

The water and minerals absorbed from the roots are transported to other parts, namely, leaves and flowers of the plants. This is achieved with the help of conducting tissues (xylem). The food synthesised by the leaves (the green parts of the plant) are also transported to other parts (roots and non-green) of the plants by the other type of conducting tissues (phloem).
Q. 12. What do you mean by “digestive enzymes”?

Ans. Digestive enzymes.
There are different types of enzymes which are used for the digestion of different food materials like carbohydrates, fats, protein etc. the process of digestion of different food materials like carbohydrates, fats, protein etc. the process of digestion involves the association of several catalystic organic compounds (enzymes). These are amylase, pepsin, trypsin, lipase and sucrase. They are known as digestive enzymes.
Q. 13. Give two Examples of each of the following:
          (a) Autotrophs                             (b) Heterotrophs
          (c) Saprotrophs                            (d) Parasites

 Ans.   (a)  Autotrophs. All green plants (neem, jamun, rose) etc.
           (b)Heterotrophs. All animals (lion, goat), man, etc.
           (c)  Saprotrophs. Bacteria and fungi (mould, yeast, mushroom).
          (d)  Parasites. Mosquito, hookworm, tapeworm, fungus, bacteria, Amarbel.
Q. 14. Explain the effect of amylase on starch.
Ans.   Effect of amylase on starch. Take 10 gm. Of wheat flour in a 100 mi. beaker, and add 30 ml of water in it. Stir the mixture with a glass rod. Take 5 ml of this liquid mixture in a test tube and add two drops of iodine solution to it. Formation of a blue black colour shows the presence of starch in wheat flour. Divide the remaining solution in two test tubes. Now, collect in the test tube, leaving aside the foam. Now, add about 2 ml saliva in about 10 ml starch solution and observe the impact of enzyme present in the saliva. For a better result, keep this test tube in a beaker containing hot water (at a temperature of about 37â—¦C) for 15-20 minutes. Test the liquid in the test tube for starch and sugar by adding iodine solution and Benedict’s solution, respectively. We observe that the starch has been converted into sugar by the saliva (amylase).

Q.  15. Explain the digestive system of man using diagram.
Ans.    (i)  Digestive system of man includes mouth, oesophagus, stomach, small intestine. Digestion starts in mouth. Intake of food is called ingestion. Teeth chew the food. Saliva secreted by salivary glands make it easy to swallow in. saliva converts starch into sugar. Food then goes to oesophagus, which is simply a tube leading to stomach. No digestion occurs in oesophagus.
           (ii)  Stomach. From the oesophagus, the food goes to stomach, which is a bag like structure. It can be distinguished into two parts. The expanded part is called cardiac part and the somewhat narrow part of stomach is called pyloric part. Digestion of food occurs in stomach. Stomach secretes various digestive juices. They help in digesting the food.
          (iii)  Intestine. Next organ of digestion is small intestine. It is a long tube seven meters long. Pancreatic juice and intestinal juice help in digestion of food. Digestion gets completed here. The digested food is absorbed here in small intestine. Absorption of food is utilized for various body functions. This is called assimilation of food. The food is then passed to large intestine where water is absorbed from food. The undigested food is passed out through anus. This is called egestion. (Fig. 2.5)

Fig. 2.5. Digestive system of man


Q. 1. Match the items given in Column I with those given in Column II

Column I
Column II
    i)  Autotrophs
   ii)  sugar
  iii)  Photosynthesis
  iv)  Hydra
   v)   Heterotrophs
  vi)   Parasites
    (a)  Carbohydrates
    (b)  Sucking
    (c)   Cholorophyll
    (d)  Green plants
    (e)   Hookworm
    (f)    Lion
Q. 2. Fill in the blanks space in the following statements:
   (i)  Ingestion is the first step in the process of …………...
 (ii)  Digestion is the breakdown of complex food materials into ………… .          
  (iii)  ……………. Plant is the common example of insectivorous plants.
  (iv)  The water is present even in the dry soil in the form of a ……….. layer on the sand particles.
    (v)  The source of energy for living organisms is ………….. .
   (vi) To take food inside the body through mouth is called …………. .
Q. 3. Choose  the true and false statements from the following:
     (i)  The breakdown of complex component of food into simpler substance is called digestion.
    (ii)  Food is not synthesised in green plant.
   (iii)  Animals are heterotrophic.
   (iv)  Amoeba is a multi-cellular organism.
    (v)  Salivary glands secrete saliva.
   (vi)   Ruminants are cud chewing animals.
  (vii)  There are four kinds of permanent teeth in our mouth.
 (viii)  Cud is a partially digested food.
   (ix)   Heterotrophs synthesis their own food.
    (x)   Pepsin is a enzymes.
Q. 4. Choose the correct option from the following:
     (i)  The breakdown of complex components of food into simpler substances is called
              (a)  digestion                                          (b) ingestion
              (c)  egestion                                           (d) assimilation
 (ii)  Number of teeth which are replaced in human beings.
             (a)  32                                                    (b) 28
             (c)  20                                                    (d) 12
(iii)  Movement of food through the oesophagus is due to
             (a)  lubrication by saliva                        (b)  peristalsis
             (c)  gravitational pull                             (d) all of these
 (iv)  Stomata of man mainly digests
             (a)  Carbohydrates                                 (b) Proteins
             (c)  Fat                                                   (d) Sucrose
  (v)  Where is bile produced?
            (a)  Gall bladder                                     (b) Blood
            (c)  Liver                                                (d) Spleen
  (vi)  The main function of the lacteals of intestine is the absorption of
             (a) amino acids                                     (b)  glucose and vitamins
             (c) lactic acid                                        (d)  fatty acids and glycerol
  (vii)  Gastric digestion takes place efficiently in     
              (a)  acidic medium                              (b)  alkaline medium
              (c)  neutral medium                            (d)  highly alkaline medium
  (viii)  Which is not digested by human?
               (a)  Protein                                         (b) Fats
               (c)  Glucose                                       (d) Cellulose
   (ix)  How many premolars teeth found in mouth?
             (a)  2                                                    (b) 4
             (c)  6                                                    (d) 8
    (x)  The teeth which helps in chewing the food we eat are
             (a)  Premolars                                      (b) Incisors
             (c)  Cannines                                       (d) Molars   
    (xi)  The finger-like projection inside ileum are called
             (a)  Caecum                                         (b) Villi
             (c)  Cristae                                           (d) Rumen
    (xii)  Trypsin is present in
              (a)  Saliva                                           (b) Intestinal juice
              (c)  Gastric juice                                 (d) Pancreatic juice
   (xiii)  The total number of molars in an adult man is
               (a) 16                                             (b) 12
               (c)  8                                              (d) 26
  (xiv)  The upper part of the small intestine is called
              (a) duodenum                                  (b) rectum
              (c) oesophagus                                (d) liver
   (xv)  The saliva contain an enzyme called
            (a) Lipase                                          (b) Ptyalin
            (c) Pepsin                                          (d) Trypsin
Q. 1.  Match the items in Column I with Column II:
Column  I
Column II
(i)   Autotrophs
(ii)  Sugar
(iii) Photosynthesis
(iv) Hydra
(v)  Heterotrophs
(vi) Parasite
   (d)   Green plants
   (a)   Carbohydrates
   (c)   Chlorophyll
   (b)   Sucking
   (f)    Lion
   (e)    Hookworm
Q. 2. Fill in the blanks:
     (i) holozoic nutrition                 (ii) simpler substances                (iii) Pitcher
   (iv) hygroscopic                          (v) Sun                                        (vi) Ingestion
Q. 3. True/False:
     (i) True                  (ii) False                (iii) True                 (iv) False
    (v) True                 (vi) True                (vii) False              (viii) True
   (ix) False                 (x) True.
Q. 4. Choose the correct option:
     (i) (a)                       (ii)  (c)                      (iii) (d)                    (iv) (b)
    (v) (c)                      (vi)  (d)                     (vii) (a)                   (vii) (d)
   (ix) (b)                      (x)   (a)                      (xi) (b)                   (xii) (d)
 (xiii) (c)                     (xiv) (a)                     (xv) (b)                   (xii) (d).