Life Processes- Nutrition notes

Notes of Chapter- Life Processes ( Nutrition)

KEY CONCEPTS & GIST 

v  Life processes – The processes that are necessary for an organism to stay alive. Eg. Nutrition, respiration,circulation, excretion etc.

v  Criteria of life- (i) Movement   ii) Growth iii) Life Processes.

v  Nutrition- The process in which an organism takes in food, utilizes it to get energy and nutrients for growth, repair and maintenance, etc. 

v  Types of nutrition                                                                          

1.       Autotrophic nutrition (Auto =self:  trophos = nourishment) E.g. Plants, Algae, blue green bacteria.

o   Process – Photosynthesis (Photo=light; Synthesis= to combine)

o   Raw materials- (i) Carbon dioxide (ii)Water

o   

Equation-                   sunlight                                                                          

o    6CO₂  +  6H₂O                                     C₆H₁₂O₆      +     6O₂

                                     Chlorophyll

o   Energy conversion- Light/Solar energy to Chemical energy

o   Role of Chlorophyll- To trap the sun’s energy for photosynthesis

o   Factors affecting Photosynthesis- (i) Carbon dioxide (ii) Water 

                                                    (iii)  Light   (iv) Temperature

o   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

o   Gaseous exchange- (i) Gas used- Carbon dioxide 

                                     (ii)  Byproduct - Oxygen

o   Source of raw materials-

(i)        Carbon dioxide – Land plants- (Air) , Aquatic plants- (Water)

(ii)       Water & Minerals - Soil

            

2.       Heterotrophic nutrition (Hetero =others:  trophos = nourishment) Eg. Animals, fungi.

 (a)Saprophytic nutrition: Organisms feeds on dead decaying plants or animals material. E.g. 

                     Fungi, Bacteria

   (b) Parasitic nutrition: Organisms obtain food from the body of another living organism. (host)

o   Endoparasite : Parasite lives inside the body of the host e.g. tapeworm, roundworm.

o   Exoparasite :  Parasite lives on the body of the host. E.g. lice, leech.

 Note- The parasite benefits while the host is usually harmed e.g. Cuscuta- plant parasite (amar bel), plasmodium (malarial parasite).

  (c) Holozoic nutrition: Organism (mostly animals) take in whole food and then digest it into smaller             particles with enzyme. Eg. Amoeba, Paramoecium. Animals, human beings.

o   Steps in Holozoic nutrition

(i)     Ingestion: taking in of food.

(ii)    Digestion: breaking down of complex food into simpler, absorbable form.

iii)    Absorption: of nutrients from digested food in intestine.

(iv)    Assimilation: Utilization of digested food from the body.

(v)     Egestion: Removing undigested food from the body

           

o   Nutrition in human beings

§  Alimentary canal-  

           Mouth → Oesophagus → Stomach → Small intestine  → Large intestine

§  Important gland/juices

         (Refer to figure 6.6 page no.97 of N.C.E.R.T  Text book)

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. (b)   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         Amylase → Trypsin   → Lipase     →	(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.( Emulsification) Converts Carbohydrates to glucose Converts Proteins to Amino acids Converts Fats into Fatty acids & Glycerol

§  Peristaltic movements- Rhythmic contraction of muscles lining the Alimentary canal (oesophagus) to push the food forward.

§  Sphincter muscle- controls the movement of food from the oesophagus to stomach ; and from stomach to intestine.

§  Villi- Small finger like projections on the walls of Small intestine- To increase the surface area for the absorption of food.