CHAPTER 1. LIVING WORLD

 

What is life?

 Life can be defined as unique complex organization of molecules expressing itself through chemical reactions which lead to growth, development, responsiveness, adaptation and reproduction.

 

Characteristics of life:-

 

1) Shape: All living organisms show definite shape and size which gets modified upto some extent due to growth.

2) Growth: The growth of a living organism is an internal & biological process controlled by protoplasm. Growth is the end result of metabolism going on in the bodies of all organisms.

3) Reproduction: All living organisms have power of reproduction which means capability to produce young ones of similar kind. Organism may reproduce by asexual and sexual methods. The continuation and multiplication of every individual is maintained to avoid extinction due to their death.

4) Metabolism: Metabolic activity may be anabolic or catabolic. Feeding, digestion and assimilation in an organism results in the production of more protoplasm and also in addition in weight of the body. It is called anabolism or constructive metabolism.

    Catabolism is a process of breakdown of complex substances into simpler one. E.g. Respiration.

5) Cellular structure: All living organism are made up of cells, and carry out variety of coordinated functions.

6) Consciousness: All living beings are aware of their surroundings. The reaction or response by living organism to the changes in environment is called sensitivity.

7) Definite life cycle: The living beings shows a systematic and orderly cycle in their life time starting from birth, growth, reproduction and death.

8) Movements: Animals are able to move freely from one place to another while plants do not exhibit any clear movement.

9) Protoplasm: All living beings shows vital activities of cell due to presence of protoplasm. Protoplasm has been called as physical basis of life.

10)   Self-regulation: A control system works in every organism which helps in regulation of body functioning.

11) Co-ordination: All the parts of an organisms co-ordinate and co-operate with one another for better functioning of body.

12)    Variations: Living organisms possess variations and ability to evolve with time.

13)   Healing: Living beings have the capacity to heal and repair the broken and injured parts.

14)   Genetic material: All living beings bear genetic or hereditary material in the form of DNA. It is responsible for expression of traits in organism.

15)   Adaptations: Adaptations are the variations which help living beings to modify themselves and show perfect harmony with changed surrounding.

16)   Death: All organisms die after a period of time. Death occurs naturally due to wear and tear.