Carbon
Cycle
- Carbon
dioxide,
either
in
the
atmosphere
or
in
solution
in
surface
waters
is
the
major
source
of
carbon
for
living
organisms.
It
is
converted
to
organic
form
by
the
autotrophs
which
use
it
as
sole
carbon
source.
The
most
important
in
this
conversion
are
the
photosynthetic
autotrophs
(seed
plants
on
land
and
algae
in
water)
that
carry
out
oxygen
producing
type
of
photosynthesis.
Photosynthetic
and
chemosynthetic
autotrophs,
chiefly
bacteria
also
play
role
in
this
conversion.
Organic
carbon
autotrophs.
A
small
part
of
the
inorganic
carbon
is
also
present
in
the
reduced
form
of
methane,
in
some
specific
habitat
conditions.
