Characters of living beings
1. Cellularity: Body of all living organisms is made up of cell. Cell s the basic structural and functional unit of life. Organisms having single cell are called unicellular and are protozoans whereas organisms having multi- cells are multicellular and are metazoans. 2. Definite shape and size: The living being possess definite shape and size except some of the lower level organisms. 3. Growth: Living organisms grow from within, using food that they obtain by nutrition. 4. Nutrition: All the living organisms need food, which is associated and used as a source of energy and materials for living process such as growth. 5. Respiration: Respiration is the process of releasing energy by oxidizing the eaten food. It involves the process of gaseous exchange. Most of animals have specific organelles for it and however, the plants do not possess specific organelles. 6. Irritability: All living organisms have the ability to respond to changes in both the internal and external environments. Such capacity provides them better chances of survival. 7. Movement: Movements is distinct in animal than in plants. Animals consists some special organs for movements whereas movements in plants are generally shown by the different part instead of the whole body. 8. Excretion: Excretion is the removal of metabolic products from the body, All the living organisms exhibit excretion process. 9. Reproduction: All the living organisms have capacity of reproducing young ones like them to maintain the continuity of life. 10. Ageing and Death: Every organisms has definite life span during which it grows, matures and reproduces. With the increase in age, there is deterioration of structure and function of different tissues, organs and cells, known as ageing. Death is the last event of life span, when body stops functioning. Death is an irreversible process necessary to continuity of life on earth.