Class notes Science

CH – 2 NUTRITION IN ANIMAL
 We need energy to grow and perform various
activities.
 We get this energy from the food we eat.
 We know that animals including humans cannot
make their own food.
 We are directly or indirectly dependent on plants
for food.
 The food we eat is digested by our digestive
system.
 The digestion of food starts from mouth.
NUTRITION IN ANIMALS
 All living organisms need nutrients from food for
growth, repair and maintenance of their bodies.
 Most animals take in complex solid organic matter.
 This mode of feeding is known as HOLOZOIC
NUTRITION.
 Food is broken down into simpler form, which is
utilized by our blood cells to provide energy.
 It involves certain steps;
1. INGESTION- Food is taken in the body through
the mouth.

, 2. DIGESTION - Large food molecules are broken
down into smaller, simpler and soluble
molecules with the help of digestive cells.
3. ABSORPTION – Digested food substances are
absorbed by the body cells.
4. ASSIMILATION – The absorbed food is used to
provide energy and for growth.
5. EGESTION – The undigested food is removed
from the body.

NUTRITION IN HUMAN




 Th
e organs of the digestive system form a canal
called alimentary canal or gut.