Characteristics and variations of Living organisms

Do you can identify a Living organisms?..yes.. all  living organisms can identify another living organisms. but scientist couldn't give a one sentence or paragraph to describe living organisms. so,We have to learn variations and Characteristics to describe living organisms. lets explore variations and Characteristics of living organisms.

Variations of Living organisms

Living organisms show a wide range of variation in size, shape, form and distribution
examples:
Size – Bacteria – 0.25   – 2   μ   to  Giant Sequoia (Giant Red Wood)– 100 m
Shape – Organisms are diverse in shape
Form – a cellular , unicellular, multi cellular
Distribution – Terrestrial, aquatic, arboreal, aerial

 Characteristics of living organisms

We can see following  Characteristics from living organisms study them carefully.

                   (1)   Order and organization
                       From molecular level to biosphere there is an order and organization in organisms to
                       perform their biological activities efficiently

                 (2)   Metabolism
                       The sum of all chemical activities taking place in an organism is  its metabolism. It
                       includes catabolic reactions and anabolic reactions.

                 (3)   Growth and development
                       All organisms begin their life as a single cell. During growth an irreversible increase
                       in dry mass occurs, which is characterized only by the living. Growth and
                       development are two consequent processes that happen in the life span of organisms.



                 (4)   Irritability and coordination
                       Irritability is the ability to respond to stimuli from both internal and external
                       environment. Movement of organisms occur as a result of irritability and
                       coordination. In animals this happens as a result of coordinated efforts of nervous,
                       muscular and skeletal systems

                 (5)     Adaptation
                       Adaptation is a a peculiarity of structure, physiology or behavior that promotes the
                       likelihood of   an organism’s survival and reproduction in a particular environment
                       e.g., sunken  stomata in xerophytes, viviparity in some mangroves,
                       production of more sweat in a hot climate, camouflage, splayed-out foot of camel
                       prevents the foot sinking into soft sand

                 (6)   Reproduction
                       Ability to produce a new offspring for continuous existence of species

                 ( 7)   Heredity & Evolution
                       Organisms have genes that pass from one generation to the next and control specific
                       physiological, morphological and behavioral characters of organisms.
                       Ability of organisms to change over time as a result of genetic modification of species
                       is   evolution


While study these notes.. you can give attention for the following points.
                •    Many non living entities have one or more of these characteristics but not all of them e.g.,
                   crystals grow, waves  move but only living organisms display all these characteristics
                   simultaneously or at some point during their life cycle.

               •    Hierarchical levels of organization: organisms are organized from molecules to biosphere
                   level. At every level, structure and functions are different and are precisely coordinated.

               •    The cell is considered as the basic structural and functional unit in the hierarchical levels
                   of organization.