Page 1 - LN-CH-16

Animals depend on ready-made food for their nutritional requirements. Nutrition is a
process by which animal obtain essential and non-essential substances called
nutrients.
The way by which organisms derive their nutrients is called mode of nutrition.
It is mainly of two types
(a) Autotrophic or Holophytic The organisms having the capability to form their own
food with the help of solar energy, e.g., Plants, Euglena, etc. It is of further two types,
i.e., photoautotropic and chemoautotrophic.
(b) Heterotrophic The organisms which cannot use free energy of our atmosphere to
synthesise necessary organic compounds as food. These normally obtain the
nourishment from the autotrophs.
Based upon the mode of feeding the heterotrophs can be
(i) Holozoic (ii) Saprozoic (iii) Saprophytic
(iv) Osmotrophic (v) Parasitic (vi) Predatorship
The myxotrophic nutrition is the case in which more than one type of . nutritional
modes are found within the single animal. The animals like Euglena show this kind of
nutrition.
A balanced diet has various components (carbohydrates, hits, proteins, vitamins,
water, mineral and roughagfi) in optimum proportion and quantity.
Human Digestive System (Structure)
Biomacromolecules in food cannot be utilised by our body in original form. So, they
are subject to a process called digestion (complex food substances are converted to
simple absorbable forms).
The system that helps in the complete process of digestion by mechanical and
biochemical methods is called digestive system.