Friday, February 26, 2016

Autotrophic, Heterotrophic and Mixotrophic Nutrition -TEXT


                                                BIOLOGY-CBSE
                                                    CLASS-VII


All the living organisms require a continuous supply of carbon containing compounds(also called principal carbon) for growth and for building their body structures
Energy is also required to maintain their daily activities and it is derived by oxidizing either organic or inorganiccompounds. Chemical compounds required for body building and for energy production are called nutrients. Intake of nutrients into the body by an organism is called nutrition.
Nutrients may be very simple or very complexinorganic or organic compounds. Different organisms require different types of nutrients
For example, several bacteria can survive with a supply of few inorganic salts. Plants use water and carbon dioxide and synthesize carboncompounds like carbohydrates. 
They also use simple nitrogen and sulphur containing compounds to synthesize complex molecules required for their growth. In contrast, amino acids, fatty acids and vitamins for their survival. 
They do not have the capacity to synthesise several chemical compounds required for their growth. They depend on other organisms for the supply of these nutrients.
All the nutrients required by an organism are usually obtained through the food they consume. Hence, several times, intake and utilization of food is considered to be similar to nutrition.
Differentorganisms use different methods to obtain their nutrients, especially of carbon source. Autotrophic, heterotrophic and mixotrophic nutrition are three modes by which organisms obtain their principal source of carbon.

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