What Is Nutrition

What Is Nutrition

Organisms need energy to live and grow. This energy is obtained from food. Any substance that can be broken down by chemical processes in the body of an organism to give energy is called food.

The process of intaking the food & utilization of food is called nutrition.


The different component of food that have distinct functions like providing energy, materials for body building, maintenance & regulation of metabolism are called nutrient.

For example – Proteins, Minerals, Vitamin, Carbohydrates, fats.

There are two main modes of nutrition: (a) autotrophic and (b) heterotrophic.

Autotrophic Nutrition:

It is a mode of nutrition in which organisms are able to build up their own organic food from inorganic raw materials with the help of energy. The organism performing autotrophic nturtion are called autotrophs. (Gk. autos-self, trophe-nourishment). e.g., Ferrobacillus (iron bacterium).


Aim: To show that only green plants can photosynthesize

Materials needed: A leaf with two colours (could be a variety of Hibiscus or Coleus), a beaker, beaker stand, Bunsen burner, water, test tube, alcohol, and iodine solution


    1. Place a beaker, about three-fourths full of water, on a stand and boil the water.
    2. Place the leaf in this water for about two minutes to soften the leaf.
    3. Take the leaf out and put it in a test tube with three-fourths alcohol.
    4. Place this test tube in very hot water for about ten minutes.

      As alcohol warms up, it will remove chlorophyll from the leaf and make it almost colourless.
    5. Take the leaf out and add four drops of iodine solution on its surface.

Autotrophic-Nutrition                             Autotrophic-Nutrition-1

Observation: On adding the iodine solution, the colourless portion shows no change, whereas the green portion turns blue-black.

Conclusion: Starch is present only in the green area of the leaf. Thus, only green leaves can photosynthesize and make food.


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