Microorganisms
are
very
____________________
living
things
.
They
are
so
small
that
you
need
a
____________________
to
see
them
.
Microorganisms
are
all
around
us
,
in
the
air
,
in
our
bodies
and
in
water
.
Some
microorganisms
are
____________________
to
us
,
but
others
are
____________________
to
us
.
Microorganisms
that
cause
____________________
are
often
called
____________________
.
Some
diseases
,
like
chickenpox
,
are
caused
by
____________________
.
____________________
caused
by
viruses
usually
spread
easily
from
one
person
to
another
.
Uncooked
foods
(
especially
meat
)
can
contain
____________________
.
The
____________________
are
killed
when
the
food
is
cooked
properly
.
But
if
you
eat
food
that
has
not
been
cooked
properly
,
the
____________________
may
survive
and
make
you
feel
very
ill
.
Bacteria
left
in
your
mouth
by
not
brushing
your
teeth
properly
can
cause
a
tooth
____________________
.
Bacteria
left
in
your
mouth
could
also
cause
an
____________________
in
your
ear
.
____________________
is
a
type
of
microorganism
that
grows
on
decaying
food
.
It
can
make
you
ill
if
you
eat
it
.
Here
are
some
examples
of
____________________
microorganisms
.
When
bread
is
made
,
a
microorganisms
called
____________________
is
added
to
the
dough
to
make
the
bread
rise
.
____________________
is
made
by
boiling
milk
and
adding
special
bacteria
to
it
.
The
bacteria
turn
the
sugar
in
the
milk
into
acid
.
The
acid
makes
the
milk
go
thick
and
stops
any
____________________
bacteria
growing
.
Inside
a
pile
of
dead
leaves
are
millions
of
tiny
____________________
.
These
bacteria
feed
on
the
leaves
and
____________________
them
down
into
____________________
.
The
____________________
go
back
into
the
soil
where
they
can
be
used
by
____________________
.
