1.Differentiate  between autotrophs and heterotrophs, giving examples of each.

     Ans: 
AUTOTROPHS
(i)    Prepare their  own food.
(ii)    Depends on sun for energy.
(iii)    Ex: Green plants.
HETEROTROPHS
(i)    Can’t prepare their own food.
(ii)    Depends on autotrophs for energy.
Ex: Non-green plants, animals, etc

3. How will you test the presence of starch in a leaf  ? Mention any precautions you will take.

    Ans:  To test a leaf for starch :  Pluck a leaf  from a plant which has been exposed to sunlight.  Boil it for about five minutes in water to soften it.  Place it in a test tube containing alcohol.  Place the test tube in a beaker of water and warm the water gently until the alcohol begins to boil.  (Caution: Do not allow the water in the beaker to boil)  The alcohol will dissolve the chlorophyll and the leaf will lose its green colour.  Wash the leaf in warm water to remove the alcohol.  Now spread the leaf  out flat on a dish and cover it with iodine  and wash it with water. Hold it up against light.  If starch is present, a blue-black colour will be seen.
Picture needed
4. All animals – whether herbivores, carnivores or omnivores – depend on plants for their. Discuss.

    Ans:  Herbivorous animals depend directly on plants for their nutrition and omnivores (man) depend on both plant and animals for their food.  Carnivores depend on other animals which in turn depend on plants food prepared by plants.  In this way all animals whether herbivores, carnivores or omnivores-depend an plants for their food.

5. List and explain in one sentence each, the various processes involved in nutrition in animals.
    Ans:  

(a)    Ingestion – Intake of food is ingestion.
(b)    Digestion –Breakdown of complex food into simple, soluble form with the help of digestive juices made in body.
(c)    Absorption – Through this process soluble food passes into the body fluid such as the blood.
(d)    Assimilation – This is the process of using the absorbed food for producing energy and for growth.
(e)    Egestion – Egestion is the elimination of undigested food.

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7.  Name the organs that make up the alimentary canal.

     Ans :  The alimentary canal is made up of mouth, oesophagus, stomach, small intestine, large intestine, rectum and anus.

8.  Name the four types of teeth in your mouth.  What are their functions?

     Ans:  The four types of teeth in our mouth are incisors, caninies, premolars and molars.

Incisors  are our front teeth they help us in cutting food.  
Canines are the tearing teeth, they are pointed in shape and located next to incisors.
Premolars and Molars are crushing and grinding teeth they are broad and have flat surface the food that enters our mouth is ground by these teeth into fine paste.

9.  What is the difference between milk teeth and permanent teeth ?

      Ans :  Milk teeth are found in the children in the age of nine months to six years.  They are temporary by nature, they fall as the child grows up.  Permanent teeth are found in the adults they replace the milk teeth.  Permanent teeth last longer in life.

10.  Where is saliva produced ?  What are it’s functions ?

Ans :  Saliva is a fluid produced in the mouth.  It is a digestive juice.  Saliva mixes up with the chewed food.  It softens the food into the mouth by greasing it, making it easier to swallow.  It helps in digesting the food we eat.

12.  What happens to food in the (i) stomach (ii) small intestine

    Ans :  (i)  Digestion process in stomach :
(a)    J-shaped stomach has digestive glands on its wall which produces digestive juices,
(b)    Stomach – muscles squeeze and liberate juices.
(c)    Juices of the glands mix with the food.
(d)    Digests the protein and fat part of the food partially.

         (ii)Digestion process in small intestine :

         Muscles in the upper part of the small intestine mix food with more digestive juices.  Some juices are secreted by the cells of the small intestine itself.  Others come from organs such as the liver and the pancreas.

        The digested food is then absorbed by the small intestine and carried to all the cells of the body by the blood.  The cells then utilize the food  to release energy.

13.  How are nutrition, respiration and transport linked ?

       Ans :   All animals including humans need certain nutrients to stay alive and grow.  These are obtained from food.  Whatever we eat, is digested and absorbed by the small intestine and taken to the cells of the body by the blood.  This is transportation of the food.

      Transported food, in the cell reacts with oxygen and liberated energy through respiration.  Thus nutrition, respiration and transport are linked with each other.

14. Briefly explain  the process of digestion in ruminants.

      Ans :  Process of digestion in ruminants :

(i)    Ruminants like cows, goats, sheep and bison have four chambered complicated stomach – the rumen, reticulum, omasum and abomasum.
(ii)    Swallowed food first of all  goes into the rumen.  In which partial digestion of food takes place.
(iii)    Now the food goes to the reticulum.  From reticulum food returns to the mouth as cud.  Now the cud is thoroughly chewed through the process of rumination.
(iv)    After chewing the food is swallowed for a second time.
(v)    Further digestion occurs in the chamber of abomasum (like human stomach) and omasum.   Then it is sent to small intestine for absorption of the nutrients.