Lesson 6 - Life processes-Class 10 Science Notes

 Life Processes

Life Process

Those processes of the body which are necessary to prevent damage and break down and which together perform maintenance job are called life processes.

Example:- growth, excretion, respiration, circulation, digestion, etc.

Bio-chemical process

For this life process organisms get complex material form outer energy sources and decomposition and formation take place inside the body. By which these are form to maintain and to growth of body. For this there happen a large series of chemical reactions. These are known as bio-chemical process. There is bio-chemical process called metabolism which takes place in the cells. These cellular process need oxygen to perform this which is obtained from external environment.

Common chemical methods for decomposing of molecules

Metabolism:- The decomposing of various molecules in the body are taken place by a chemical process is called metabolism.

Metabolisms are a bio-chemical process which occur in all living organisms to ensure life.

There are two kinds of metabolisms-

(i) Catabolism:- During this process complex organic materials are decomposed into simpler molecules and during cellular respiration these simpler molecules are used to form energy.

(ii) Anabolism:- It is a group of constructive chemical reactions in which the energy generated by the process of reduction is used to form complex molecules from simple molecules. By this process, all the essential nutrients are transported to other parts of the body as per the need, due to which new cells or tissues are formed.

Types of  Processes

Some types of processes we shall study-

1. Nutrition:- The process by which an organism takes food and utilizes it, is called nutrition.

2. Respiration:- The process by which a living being takes and  utilizes the food to get energy, is called respiration.

3. Transportation:- Movement of food, water, minerals, and other substances from one part to another part in plants or animals is called transportation.

4. Excretion:- Removal of harmful metabolic waste from the body of organisms is called excretion.

Nutrition

The process happening in the living organisms in which organisms get energy to change complex materials into simple materials by the biochemical process and utilizes them, is called nutrition.

Examples of biological process:

i) Photosynthesis in plants

ii) Digestion in animals

Need of Nutrition:- 

Organisms need the energy to perform various activities. The energy is supplied by the nutrients. Organisms need various raw materials for growth and repair. These raw materials are provided by nutrients.

Nutrients:- 

Materials which provide nutrition to organisms are called nutrients. 

• Carbohydrates, proteins and fats are the main nutrients and are called macronutrients. 
• Minerals and vitamins are required in small amounts and hence are called micronutrients.

Modes of Nutrition

There are two modes of nutrition-

1. Autotrophic Nutrition (Self sufficient for food)

2. Heterotrophic Nutrition (Dependent on others for food)

Autotrophic Nutrition

The mode of nutrition in which an organism prepares its own food is called autotrophic nutrition. Green plants, trees, blue-green algae and some other organisms obtain self-nutrition by making their own food, so these organisms are the recipients of autotrophic nutrition. 

• The organisms which carry out autotrophic nutrition are called autotrophs (green plants).

• Autotrophic nutrition is fulfilled by the process, by which autotrophs intake CO2 and H2O, and convert these into carbohydrates in the presence of chlorophyll, sunlight is called photosynthesis.
• Equation of photosynthesis

Nutrition in Plant

Green plant prepare their own food. They make food in the presence of sunlight. sunlight provides energy, carbon dioxide and water are the raw materials and chloroplast is the site where food is made.

Photosynthesis

Photosynthesis is made  up of two words "Photo" and "Synthesis". In this "photo" means "light" and "synthesis" means "to make", i.e. the process of making or making in the presence of sunlight.

Substances required for photosynthesis

(i) Sunlight

(ii) Carbon dioxide

(iii) Water and 

(iv) Chlorophyll

In the process of photosynthesis all the above is essential. In the absence of any of these, the process of photosynthesis would not be complete.

Stages of Photosynthesis

(i) Absorption of light energy by chlorophyll.

(ii) Conversion of light energy into chemical energy.

(iii) Decomposition of water molecules into hydrogen and oxygen.

(iv) Reduction of carbon dioxide into carbohydrates.

Process of photosynthesis

• The leaves of green plant look green because of the chlorophyll present in them.
• Leaf cells contain green dotted cell organelles called chloroplasts, which contain chlorophyll. These chlorophyll present in green leaves absorb energy form sunlight and convert it into chemical energy.
• Plants take water from the ground through their roots. The energy received by chlorophyll form sunlight splits water into hydrogen and oxygen.
• Their are tiny pores present on the surface of the leaves, called stomatal pores. The leaves absorb carbon dioxide from the air through these stomatal pores. The exchange of gas in the leaves takes place through these stomatal pores.

• The carbon dioxide obtained by the leaves reacts with the oxygen and hydrogen form the water and gets reduced to glucose.

Stomata

There are tiny pores present in the epidermis of leaf or stem through which gaseous exchange and transpiration occur.

Function of stomata

• Exchange of gases, O2 and CO2
• Loses a large amount of water (water vapour) during transpiration.

Opening and Closing of stomatal pores

• The opening and closing of stomatal pores are controlled by the turgidity of guard cells.
• When guard cells uptake water from surrounding cells, they swell to become a turgid body, which enlarges the pore in between (stomatal opening).
• While, when water is released, they become flaccid shrinking to close the pore (stomatal closing).

The sequence of the process of photosynthesis in plants growing in the desert

Plants growing in the desert obtain carbon dioxide at night and form an intermediate product. Then during the day they get energy form sunlight and make glucose from that intermediate product.

Plants require energy as well as other raw materials to build the body. Terrestrial plants obtain water as well as other raw materials such as nitrogen, phosphorus, iron and magnesium, etc. minerals from the soil. Nitrogen, which is an essential element, is used in the synthesis of proteins and other essential compounds. Nitrogen is obtained as nitrite of inorganic nitrate. These are the inorganic substances that bacteria make from atmospheric nitrogen.

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