Class 10 | Science 2 | Easy notes on chapter 2 Life processes in living organisms part -1

Class 10 | Easy notes on chapter 2 Life processes in living organisms part -1 

Living Organisms and Life Processes :

There are certain basic vital life processes, which are essential for an organism to stay healthy and to maintain the proper functioning of the body’s organ systems. 

Important life processes include digestion, nutrition, transportation, respiration, reproduction, circulation and excretion, which help in the maintenance of living organisms.

Our body required different nutrients like carbohydrates, fats, proteins, vitamins, minerals,etc.

Sources of carbohydrates :

milk, fruits, jaggary, cane sugar, vegetables, potatoes, sweet potatoes, sweet meats and cereals like wheat, maize, ragi, jowar, millet, rice, etc.

    Types of Respiration :

Body level respiration

• Exchanging oxygen and carbon dioxide

Cell level respiration

• Cell level respiration means oxidization of food to generate energy and waste products

• Note: The term ‘oxidation’ sounds like ‘oxygen’. But

oxidation can happen with or without oxygen.

Energy production from carbohydrates :

• Energy is produced from carbohydrates by cellular respiration.

• Carbohydrates are mainly utilized for production of energy required for daily need. This energy is obtained in the form of ATP.

• We get 4Kcal energy per gram of carbohydrates.

• Cellular respiration :

Glucose, a type of carbohydrate is oxidized step by step in the cells. This is called as cellular respiration. 

• Cellular respiration occurs among the living organisms by

two methods. 

1. aerobic respiration (oxygen is involved).

2. anaerobic respiration (oxygen is not involved). 

Aerobic respiration :

In aerobic respiration, glucose is oxidized in three steps.

1. Glycolysis

2. Tricarboxylic acid cycle 

3.Electron transfer chain reaction

1. Glycolysis (EMP pathway) :

• Process of glycolysis occurs in cytoplasm.

• A molecule of glucose is oxidized step by step in this process and two molecules of each i.e. pyruvic acid, ATP, NADH2 and water are formed.

• Molecules of pyruvic acid are converted into molecules of

Acetyl-Coenzyme-A. Two molecules of NADH2 and two molecules of CO2 are released during this process.

2. Tricarboxylic acid cycle (Kreb's cycle) :

• Both molecules of acetyl-CoA enter the mitochondria.

• Cyclic chain of reactions called as tricarboxylic acid cycle is operated on it in the mitochondria.

• Acetyl part of acetyl-CoA is completely oxidized through this cyclical process and molecules CO2, H2O, NADH2, FADH2 are formed.

3. Electron transfer chain

reaction :

• Molecules of NADH2

 and FADH2 formed during all above processes participate in electron transfer chain reaction. • Due to this, 3 molecules of ATP are obtained from each NADH2 molecule and 2 molecules of ATP from each FADH2 molecule.

• Besides ATP, water molecules

are also formed in this reaction.

• Electron transfer chain reaction is operated in mitochondria only.

• Thus, a molecule of glucose

is completely oxidized in aerobic respiration and molecules of CO2 and H2O are produced along with energy.

• Energy from lipids and proteins :

Lipids and proteins used for energy production, If there is insufficient amount of carbohydrates in body due to exceptional conditions like fasting and hunger.

• In case of lipids, they are converted into fatty acids whereas proteins into amino acids.

• Fatty acids and amino acids are converted into acetyl-CoA and energy is obtained

through complete oxidation of acetyl-CoA by the process of Kreb's cycle in mitochondria.

Energy Production in Microorganisms through Anaerobic Respiration :

• Some organisms cannot live in presence of oxygen.

Ex. Many bacteria. 

• These organisms perform anaerobic respiration for energy production.

• There are two steps involved in anaerobic respiration

 i.e. Glycolysis and

fermentation

• Glucose is incompletely oxidized and less amount of energy is obtained in this type of respiration.

• Pyruvic acid produced through glycolysis is converted into other organic acids or alcohol with the help of some enzymes. This is called as fermentation.

• higher plants, animals and aerobic microorganisms also perform anaerobic respiration instead of aerobic respiration if there is depletion in oxygen level in the surrounding.

Ex. i. Seeds perform anaerobic respiration if the soil is submerged under water during

germination.

ii. Our muscle cells also perform anaerobic respiration while performing the exercise. Due to this, less amount of energy is produced in our body and lactic acid accumulates due to which we feel tired.

• Excess of the carbohydrates are stored in liver and muscles in the form of glycogen.