Chapter- Life processes - Nutrition
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
|
(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.
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