What is Living ?
Whenever we try to define living we conventionally look for different
distinct characteristics exhibited by living organisms like Growth,
reproduction, ability to sense environment and mount a suitable response
come to our mind immediately as unique features of living organisms.
We can add few more features like metabolism, ability to self replicate,
self- organize, interact and emergence to this list.
1.Growth As Living Character
Growth may be of two types either increase in number or increase in mass of
the individuals.
In Unicellular organism cell division itself a mode of growth. They simply
multiply their number by dividing their cell by mitosis or meiosis.
In Multicellular organism growth is mutually related to reproduction.
Note: But mind it non- living organisms can also shows growth in their
mass. For example non - living objects shows growth by accumulating
materials from outside on the surface.
In Non - Living objects growth is external but in living organism growth is
internal.
2. Reproduction as Living Character
In case of reproduction only living object can reproduce.
But when we talk about unicellular and Multicellular word reproduction
becomes more complicated.
In case of unicellular cell division itself a mode of
reproduction. But in case of multicellular organism reproduction is a
very complicated process to make their own copy.
However reproduction is not seen in infertile couple, Male Worker Bees etc.
So we can not consider reproduction as a living character for all living
being.
Obviously non living thing can't reproduce.
3. Self Consciousness As Living Character
A living thing have self consciousness i.e. they response to the external stimuli. No non living thing have self consciousness.
But when we consider Human in coma, who doesn't poses self consciousness.
Its become more complex to decide whether self consciousness is a living
character.
4. Metabolic Reaction As Living Character
All living organism performs metabolic reaction to be alive
at cellular level. But no non living organism performs any kind of metabolic
reaction.
So Metabolic reaction is the defining characteristics of living
organism.