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A Handbook of Biology

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Life is a unique, complex organisation of molecules, expressing through

chemical reactions which lead to growth, development, responsiveness,

adaptation & reproduction.

PRØPËRTÏËS ØF LÏVÏÑG ØRGÅÑÏSMS

1. GRØWTH

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It is the increase in number & mass of cells by cell division.

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In plants, growth continues throughout their lifespan.

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In animals, growth is seen only up to a certain age. However, cell division

occurs to replace lost cells.

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Basically, growth is the increase in mass & size. Thus non-living objects

also grow (surface accumulation of material). So growth is not a defining

property of living organisms.

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In living organisms, growth is from inside. (Intrinsic growth)

2. RËPRØDÜÇTÏØÑ

It is the production

of progeny having

features similar to

those of parents.

Organisms

reproduce

asexually and

sexually.

In unicellular

organisms, growth

& reproduction are

same because

they reproduce by

cell division.

Lower organisms

reproduce by

different methods

such as budding,

regeneration, etc.

Many organisms do

not reproduce (e.g.

mules, worker bees,

infertile human

couples, etc). Hence,

reproduction is not

a perfect defining

property of living

organisms.