Maharashtra Board Class 10 Science Part 2 Chapter 2 Life Processes in living organisms Part 1 PDF Download

Life Processes In Living Organisms Part -1

Living Organisms & Life Processes

Living Organisms & Energy Production

Some Nutrients & Energy Efficiency

Cell Division- A Life Process

Can you recall?

1. How are the food stuffs and their nutrient contents useful for body?

2. What is the importance of balanced diet for body?

3. Which different functions are performed by muscles in body?

4. What is the importance of digestive juices in digestive system?

5. Which system is in action for removal of waste materials produced in human body?

6. What is the role of circulatory system in energy production?

7. How are the various processes occurring in human body controlled? In how many ways?

Living Organisms and Life Processes

Various organ-systems are continuously performing their functions in human body. Along with the various systems like digestive, respiratory, circulatory, excretory and control systems, different external and internal organs are performing their functions independently but through a complete co-ordination. This overall system is in action in more or less same way in all the organisms. Those are in need of continuous source of energy for this purpose. Carbohydrates, fats and lipids are the main sources of this energy and it is harvested by the mitochondria present in each cell. It is not like that only foodstuff is sufficient for energy production but oxygen is also necessary. All these i.e. food stuffs and oxygen are transported up to the cell via circulatory system. Besides, it is coordinated by the control system of the body. i.e. each life process contributes in its own way in the process of energy production. Functioning of all these life processes also requires the energy.

Human and other animals consume the fruits and vegetables. Plants are autotrophs. They prepare their own food. They utilize some of the food for themselves whereas remaining is stored in various parts like fruits, leaves, stem, roots, etc. We consume all these various plant materials and obtain different nutrients like carbohydrates, fats, proteins, vitamins, minerals, etc. Which food materials do we consume to obtain these nutrients?

We obtain the carbohydrates from milk, fruits, jaggary, cane sugar, vegetables, potatoes, sweet potatoes, sweet meats and cereals like wheat, maize, ragi, jowar, millet, rice, etc. We get 4Kcal energy per gram of carbohydrates. Let us study the way by which this energy is obtained.

Many players are seen consuming some food stuffs during breaks of the game.

Use your brain power

Why may be the players consuming these food stuffs?

Teacher's Note

Players eat food during games because their body needs quick energy. Just like your phone battery drains fast when you play games, your body uses up energy when playing sports.

Exam Trick

Remember: Players eat food = they need energy fast. Energy comes from carbohydrates. Carbohydrates give 4 Kcal per gram.

Points to Remember

Plants make their own food and store it in fruits and leaves.
We get carbohydrates from rice, wheat, fruits and potatoes.
Our body needs oxygen and food to make energy.
Energy is made in a cell part called mitochondria.
Energy comes from breaking down carbohydrates, fats and proteins.

Living organism and Energy production

Observe and Label the diagram given beside.

In living organisms, respiration occurs at two levels as body and cellular level. Oxygen and carbon dioxide are exchanged between body and surrounding in case of respiration occurring at body level. In case of respiration at cellular level, foodstuffs are oxidized either with or without help of oxygen.

2.1 Human respiratory system

Can you tell?

1. How many atoms of C, H and O are respectively present in a molecule of glucose?

2. Which types of chemical bonds are present between all these atoms?

3. In terms of Chemistry what happens actually when a molecule is oxidized?

Carbohydrates of the food that we consume everyday are mainly utilized for production of energy required for daily need. This energy is obtained in the form of ATP. For this purpose, glucose, a type of carbohydrates is oxidized step by step in the cells. This is called as cellular respiration. Cellular respiration occurs among the living organisms by two methods. Those two methods are aerobic respiration (oxygen is involved) and anaerobic respiration (oxygen is not involved). In aerobic respiration, glucose is oxidized in three steps.

1. Glycolysis

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 formed in this process 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

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 derived.

Teacher's Note

Glycolysis means breaking glucose. Think of it like breaking a big chocolate into small pieces. Each piece gives us energy.

Exam Trick

Remember: Glycolysis = breaking glucose in cytoplasm. It gives ATP (energy), pyruvic acid and water. No oxygen needed here.

Points to Remember

Glycolysis happens in the cytoplasm of the cell.
Glucose breaks down into pyruvic acid in glycolysis.
ATP is the energy given out in glycolysis.
Tricarboxylic acid cycle happens in mitochondria.
This cycle breaks down pyruvic acid completely.

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.

NADH2 - Nicotinamide Adenine dinucleotide

FADH2 - Flavin adenine dinucleotide

Both enzymes are formed in the cells and used in cellular respiration.

If there is insufficient amount of carbohydrates in body due to exceptional conditions like fasting and hunger, then lipids and proteins are used for energy production. 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 Krebs cycle in mitochondria.

2.2 Mitochondria and Tri-carboxylic acid cycle

2.3 ATP: Energy Currency

ATP: Adenosine triphosphate is energy-rich molecule and energy is stored in the bonds by which phosphate groups are attached to each other. These molecules are stored in the cells as per need. Chemically, ATP is triphosphate molecule formed from adenosine ribonucleoside. It contains a nitrogenous compound-adenine, pentose sugar- ribose and three phosphate groups. As per the need, energy is derived by breaking the phosphate bond of ATP; hence ATP is called as 'energy currency' of the cell.

Teacher's Note

ATP is like money in our body. Just like we use rupees to buy things, our cells use ATP to do work. Breaking ATP bonds gives energy.

Exam Trick

Remember: ATP = energy currency of the cell. It has adenine, ribose and phosphate. Breaking the phosphate bond releases energy.

Points to Remember

ATP is the energy molecule in our cells.
It is made of adenine, ribose and phosphate groups.
Breaking ATP bonds releases energy for work.
ATP is called the energy currency of the cell.
Cells make and store ATP as they need.

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