____________________
is
made
of
many
gases
.
Nitrogen
,
oxygen
and
carbon
dioxide
are
some
of
these
gases
.
Oxygen
is
required
by
living
things
during
____________________
as
it
helps
____________________
energy
from
our
food
.
Without
oxygen
,
fire
cannot
____________________
!
Carbon
dioxide
is
needed
by
plants
to
conduct
____________________
.
Carbon
dioxide
is
also
produced
during
____________________
.
When
we
respire
,
the
air
we
breathe
in
travels
from
our
nose
,
down
our
____________________
,
into
our
lungs
.
The
air
sacs
in
our
lungs
have
____________________
walls
and
are
rich
in
____________________
____________________
.
The
____________________
in
the
air
is
absorbed
and
transported
to
the
various
parts
of
our
____________________
through
the
blood
vessels
.
