science ch 1

2. Class-7Th - Science-Chapter 1- Nutrition In Plant
Nutrition:
 Food gives us energy to carry out the basic activities of life (Life Processes).
 The process by which an organism procures food is called Nutrition .
 Nutrition is basically two types . they are :- Autotropic and Hecterotropic
Modes of Nutition
Autotropic Hecterotropic

3. • Autotropic Nutrition :-
 Autotrophic nutrition is a process where an organism prepares its own
food from a simple inorganic material like water, mineral salts and
carbon dioxide in the presence of sunlight.
 The term “autotrophic” is formed by the combination of two terms,
“auto” meaning self, and “trophic” meaning nutrition.
 Example - Maize plant, Grass, Wheat, etc.
Class-7Th - Science-Chapter 1- Nutrition In Plant
• Hecterotropic Nutrition
 Heterotroph is an organism that is unable to synthesize its own food, and
therefore, has to rely on other sources, specifically plant and animal
matter.
 All animals and non-photosynthetic plants are classified as heterotrophs
since they are unable to prepare food.

4. • Other modes of Nutrition :-
 Parasyte :-
 is a type of nutrition in which organisms live on or inside the bodies of their
hosts and feed on them.
 The parasite is the organism that obtains the food, and the host is the
organism from which the food is taken.
 Example - lice on humans and ticks on dogs.
Class-7Th - Science-Chapter 1- Nutrition In Plant

5. • Saprotrophs :-
 ​The organisms that feed on the dead and decaying organisms are called
saprotrophs.
 These organisms perform external digestion where they break down the
complex nutrients in the dead organism by releasing enzymes outside.
 Fungi is a saprotroph which feed on surface of bread.
 Fingi also grows on pickle, leather, etc.
Class-7Th - Science-Chapter 1- Nutrition In Plant

6. • Syboisis:-
 Symbiosis refers to the close relationship amongst two different organisms or living things
belonging to different species.
 Symbiosis is a relationship that exists between two organisms.
Class-7Th - Science-Chapter 1- Nutrition In Plant

7. • How are Nutrition Replenished in soil
 Nutrients in the soil are replenished by adding fertilisers and manures.
 Fertilisers and manures contain plants nutrients and minerals like nitrogen, phosphorus and
potassium.
 The bacterium called Rhizobium can take atmospheric nitrogen and convert it into a soluble
form.
Class-7Th - Science-Chapter 1- Nutrition In Plant