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Growth is not a defining property of living.Why?
All living organisms grow. Increase in mass and increase in number 
of individuals are twin characteristics of growth. A multicellular organism 
grows by cell division. In plants, this growth by cell division occurs 
continuously throughout their life span. In animals, this growth is seen 
only up to a certain age. However, cell division occurs in certain tissues to 
replace lost cells. Unicellular organisms also grow by cell division. One 
can easily observe this in in vitro cultures by simply counting the number 
of cells under the microscope. In majority of higher animals and plants, 
growth and reproduction are mutually exclusive events. One must 
remember that increase in body mass is considered as growth. Non-living 
objects also grow if we take increase in body mass as a criterion for growth. 
Mountains, boulders and sand mounds do grow. However, this kind of 
growth exhibited by non-living objects is by accumulation of material on 
the surface. In living organisms, growth is from inside. Growth, therefore, 
cannot be taken as a defining property of living organisms. Conditions 
under which it can be observed in all living organisms have to be explained 
and then we understand that it is a characteristic of living systems. A 
dead organism does not grow. 


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