What is life? Life is unique, complex organisation of molecules, expressing itself through itself through chemical reactions which lead to growth, development, responsiveness, adaptation and reproduction.
Organism having ‘Life’ is known as living beings
- Living things: Birds, human beings, elephant, insects etc
- Non Living things: Car, paper, pencil, stones etc
The various characteristics of living things are as follows
- Definite shape and structure
- Cellular structure: All living organisms are made of cells. They are either unicellular (examples: Amoeba, Chlorella) or multicellular (Human beings, higher plants).
- Specific organization: Various levels of organisation are organism, organ system, organs, tissue, cell organelles.
|Level of Organization in Biology|
- They have the ability of movements and locomotion.
- Plants do not show locomotion, but they do show movements. Plants push their roots their roots deeper into the soil in search of water and minerals.
- Nutrition:All living organisms feed on a variety of substances.
- All living organisms respond to changes in external environment.
- Adaptation is another feature of living organisms.
- These have definite life span.