CBSE Class 10 : Life Process Topic Nutrition , Class Notes Biology Science
Nutrition- The
process in which an organism takes in food, utilizes it to get energy, for growth,
repair and maintenance, etc. and excretes the waste materials from the body.
·
Autotrophic
nutrition(Auto
=self: trophos = nourishment) E.g.
Plants, Algae, blue green bacteria.
a) Energy conversion- Light/Solar energy
to Chemical energy
b) Role off Chlorophyll- To trap the
sun’s energy for photosynthesis
c) Environmental Factors- (i) Carbon
dioxide (ii) Water(iii) Light (iv) Temperature
d) Events/ Steps of
photosynthesis-
i)
Absorption
of light energy by chlorophyll
ii)
Conversion
of light energy to chemical energy & Splitting of water molecule into
Hydrogen & oxygen
iii)
Reduction
of Carbon dioxide to Carbohydrate
e) Gaseous exchange-
(i) Gas used- Carbon dioxide
(ii)
By product - Oxygen
f) Source of raw materials-
·
Heterotrophic
nutrition
(Hetero = others: trophos = nourishment)
Eg. Animals, some plants and fungi.
1.
Saprophytic
nutrition: Organisms feeds on dead decaying plants or animal’s material.
2.
Parasitic
nutrition: Organisms obtain food from the body of other living organisms (host)
3.
Holozoic
nutrition: Organism (mostly animals) takes in whole food and then digests it
into smaller particles with enzyme.
4.
Steps
in Holozoic nutrition
5.
Ingestion:
taking in of food.
6.
Digestion:
breaking down of complex food into simpler, absorbable form.
7.
Assimilation:
Utilization of digested food from the body.
8.
Egestion:
Removing undigested food from the body
9.
Nutrition
in human beings
10. Alimentary canal-
|
Mouth → Oesophagus → Stomach → Small intestine → Large
intestine → Rectum → Anus
|
|
Organ
|
Gland
|
Enzyme/Juice
|
Function
|
|
Mouth
|
Salivary glands
|
Salivary Amylase
|
Converts starch
into sugar
|
|
Stomach
|
Gastric glands
|
Gastric juice-
(i) Hydrochloric
acid →
(ii) Pepsin →
(iii) Mucus →
|
(a) Kills harmful
bacteria that
enters with the
food.
(a)
Makes
the medium acidic
for the action of Pepsin
Digests proteins
Protects the
inner lining of the stomach from the corrosive action of Hydrochloric
acid.
|
|
Small intestine
|
1) Liver
2) Pancreas
|
(i) Bile juice →
(ii) Pancreatic
Juice
|
(a) Makes the
medium Alkaline
for the action of Pancreatic
enzymes.
(b) Breaks down
large fat
molecules into smaller globules
so that enzymes can act upon
them.
Converts Carbohydrates
to glucose
Converts Proteins
to Amino acids
Converts Fats into
Fatty acids & Glycerol
|
·
Peristaltic
movements- Rhythmic contraction of muscles of the lining of Alimentary canal to
push the food forward.
·
Sphincter
muscle- Helps in the exit of food from the stomach.
·
Villi
and microvilli- Small finger like projections on the walls of-
·
Small
intestine- To increase the surface area for the absorption of food.
·
Large
intestine- For absorption of water.
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