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


Salivary glands
Salivary Amylase
Converts starch into sugar
Gastric glands
Gastric juice-
(i) Hydrochloric

(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
  • Amylase →
  • Trypsin  
  • Lipase    

(a) Makes the medium Alkaline
      for the action of Pancreatic
(b) Breaks down large fat
     molecules into smaller globules
     so that enzymes can act upon

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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