Jayalakshmi

Nutrition :-
Nutrition is the process of taking food by an organism and its
utilisation by the body to build the body, for growth, to repair the
damaged parts of the body and for energy.
Life on earth depends on carbon based molecules and most of the
food are also carbon based molecules. The outside raw materials
used by living organisms are food, water and air.
a) Modes of nutrition :- There are two main modes of nutrition. They
are autotrophic nutrition and heterotrophic nutrition.
i) Autotrophic nutrition :- is nutrition in which organisms prepare their
own food from simple inorganic substances like carbon dioxide and
water in the presence of sunlight and chlorophyll.
Eg :- all green plants and some bacteria.
ii) Heterotrophic nutrition :- is nutrition in which organisms get their
food directly or indirectly from plants.
Eg :- all animals fungi and some bacteria.
b) Types of heterotrophic nutrition :- There are three main types of
heterotrophic nutrition. They are saprophytic, parasitic and holozoic
nutritions.

i) Saprohytic nutrition :- is nutrition in which organisms get their food
from dead and decaying organisms. They break down the food material
outside their body and then absorbs it. Eg :- mushroom, bread mould,
yeast, some bacteria etc.
ii) Parasitic nutrition :- is nutrition in which organisms get their food
from living organisms (host) without killing them. Eg :- cuscuta,
orchids, ticks, lice, leeches, round worm, tape worm, plasmodium etc.
iii) Holozoic nutrition :- is nutrition in which organisms take food
directly and then digests and absorbs it. Eg :- amoeba, paramaecium,
birds, fishes, humans etc.