LECTURE 1: CLASS 10: LIFE PROCESSES

CLASS X   |    SCIENCE    |    LIFE PROCESSES

      Notes prepared by Subhankar Karmakar

---

click to access other class notes

SCIENCE: CLASS X: CBSE (CLASS NOTES)

---

A. CHARACTERISTICS OF LIVING THINGS

FOR 1 TO 1 ONLINE CLASSES OVER ZOOM PLATFORM AT REASOBLE PRICE

BOOK YOUR CLASS, CALL AT 7002561074

The characteristics of living things:

• 1. Living things can move by themselves
• 2. Living things need food air and water
• 3. Living things can grow
• 4. Living things can respond to changes around them. They are sensitive.
• 5. Living things respire
• 6. Living things excrete
• 7. Living things can reproduce.  

B. LIFE PROCESSES

The basic functions performed by living organisms to maintain their life on this earth are called life processes. The basic life processes common to all the living organisms are:

• a. Nutrition and Respiration
• b. Transport and Excretion
• c. Control and Coordination
• d. Growth
• e. Movement
• f. Reproduction

C. NUTRITION

All the living organisms need energy to perform various life processes and they get it from the food they take. 

• Food: 

Food is an organic substance. The simplest food is glucose. 

Carbohydrates and fats are the nutrients which are used by an organism mainly as a source of energy whereas proteins and mineral salts are the nutrients used by an organism for the biosynthesis of its body constituents like skin blood etc. 

• Nutrition:

Nutrition is a process of intake of nutrients like carbohydrates fats proteins minerals vitamins and water by an organism as well as the utilisation of this nutrients by the organism.

• Nutrient:

A nutrient can be defined as a substance which an organism obtains from the surroundings and uses it as a source of energy or for the biosynthesis of its body constituents like tissues and organs. It may be organic or inorganic substance. 

D. MODES OF NUTRITION

Modes of Nutrition means methods of preparing food or obtaining food by an organism. There are mainly two modes of Nutrition. 

• 1. Autotrophic, and 
• 2. Heterotrophic

E. AUTOTROPHIC NUTRITION:  

• Autotrophic nutrition is that mode of nutrition in which an organism makes or synthesizes its own food from the simple inorganic materials like carbon dioxide and water present in the surroundings. 
• The green plants have an autotrophic mode of nutrition. Therefore, all the green plants are autotrophs. The autotrophic bacteria also obtain their food by the autotrophic mode of nutrition. Most of the bacteria are not autotrophic the organisms having autotrophic mode of nutrition are called autotrophic organisms or just autotrophs. 
• The autotrophic organisms or autotrophs contain the green pigment called chlorophyll which is capable of trapping sunlight energy. 

How does autotrophs prepare their food?

The autotrophic organisms contain the green pigment called chlorophyll which is capable of trapping sunlight energy. This trapped sunlight energy is utilised by the autotrophs to make food by combining organic materials like carbon dioxide and water present in the environment by the process of photosynthesis. Thus the autotrophs make their own food by photosynthesis. 

F. HETEROTROPHIC MODE OF NUTRITION

• Heterotrophic nutrition is that mode of nutrition in which an organism cannot make or synthesize its own food from simple inorganic materials like carbon dioxide and water and depends on other organisms for its food.
• All the animals have a heterotrophic mode of nutrition. Most bacteria and fungi also have heterotrophic mode of nutrition. The organisms having heterotrophic mode of nutrition are called heterotrophs. 
• Those organisms which cannot make their own food from inorganic substances like carbon dioxide and water and depend on other organisms for their food are called heterotrophs. The non green plants like yeast are also heterotrophs.

G. TYPES OF HETEROTROPHIC NUTRITION

A heterotrophic organism can obtain its food from other organisms in three ways. Therefore, there are three types of heterotrophic nutrition.

• 1. Saprotrophic nutrition
• 2. Parasitic nutrition and 
• 3. Holozoic nutrition. 

• SAPROTROPHIC NUTRITION
• Saprotrophic nutrition is that nutrition in which an organism obtains its food from the organic matter of dead plants, dead animals and rotten bread etc. 

• The organisms having saprotrophic mode of nutrition are called saprophytes.
• Saprophytes are the organisms which obtain their food from like rotten leaves, dead and decaying animal bodies and other decaying organic matter like rotten bread.
• Examples. Fungi like bread moulds, mushrooms and yeast and many bacteria are saprophytes. 

• PARASITIC NUTRITION
• The parasitic nutrition is that nutrition in which an organism derives its food from the body of another living organism called its host without killing it. 
• The organism which obtains the food is called a parasite and the organisms from whose body food is obtained is called the host. A parasite is an organism plant or animal which feeds on another living organism known as host. 
• Example. Most of the disease causing organism are parasites. Parasitic mode of nutrition is observed in several fungi bacteria a few plants like Cuscuta and some animals like plasmodium and roundworms. 
• Malaria parasite: Plasmodium is known as  malaria parasite.

• HOLOZOIC NUTRITION
• The holozoic nutrition is that nutrition in which an organism takes the complex organic food materials into its body by the process of ingestion the ingested food is digested and then absorbed into the body cells of the organism. 
• The undigested and un absorbed part of the food is thrown out of the body of the organism by the process of egestion. 
• Examples. Man, cat, dog, cattle, deer, tiger, lion, and amoeba have the holozoic mode of nutrition.