Page 6 - Science Class 07

other eat aqua c animals. Amphibians like frog, helps in trapping energy from the sun. They
crocodile, etc. eat other animals. Plants do not prepare their own food by u lising the solar
take food from other plants or from other energy, water and carbon dioxide by the
animals. They synthesise their food on their process of photosynthesis. This results in
own. Though different living beings eat different forming of glucose.

kinds of food yet the basic components of food Plants like blue-green algae and cyanobacteria
are almost similar. could be considered as the examples of
Let us see: autotrophic nutri on.

Photosynthesis
The term photosynthesis is made up of two
words namely ‘photo’ means light and

‘synthesis’ means to combine. Therefore, the
way of making food by green plants in the
Nutri on in Human
presence of sunlight is called photosynthesis.
Nutri on in Plant
Process of Photosynthesis

The plants contain green pigment in their
leaves called chlorophyll. These green
pigments trap sunlight during the day and
convert light energy into chemical energy. Thus,
Nutri on in Animal sun is the ul mate source of energy for all

MODES OF NUTRITION living organisms.
Sunlight
The ways of obtaining food are referred to as
modes of nutri on.
We can classify nutri on in plants in two
categories. Oxygen (O ) Carbon
2
dioxide (CO )
2
v Autotrophic Nutri on
v Heterotrophic Nutri on

AUTOTROPHIC NUTRITION
Auto = self, trophic = nutri on. The literal Water
and
meaning of this term is self-nutri on. Minerals

Autotrophic nutri on is a process where the Photosynthesis
organisms prepare their food from the simple
Water absorbed by the roots is sent to different
inorganic materials like water, mineral, salt and
parts of the plants, during the process of
carbon dioxide in the presence of sunlight. All
photosynthesis. Water molecules present in the
the green plants possess an autotrophic mode
cells break up and the oxygen present in water
of nutri on.
is set free.
The autotrophic organisms contain a green
2H O 2H + O
coloured pigment called chlorophyll which 2 2 2
6 Science-7