All living organisms grow. Increase in mass and increase in number are twin characteristic of growth. Multicellular organisms grow by cell division. In plants, growth occurs continuously throughout their life span. Non living organisms also grow if we take increase in body mass as criterian for growth. However, this kind of growth exhibited by non living objects is by accumulation of the material on surface. Growth, therefore cannot be taken as defining property of living organisms What are the twin characteristics of growth?