BIO 390 Lab Exam.

BIO
390
Lab
Exam
What
is
the
primary
use
of
slants?
-
CORRECT
ANSWER-To
provide
a
solid
growth
surface
that
is
easier
to
store/transport.
What
is
the
primary
use
of
deeps?
-
CORRECT
ANSWER-To
allow
anaerobic
bacteria
to
grow.
What
is
the
primary
use
of
broths?
-
CORRECT
ANSWER-To
grow
large
numbers
of
bacteria
in
a
small
space.
Can
we
determine
whether
a
broth
culture
is
pure
by
visually
inspecting
it
without
a
microscope?
-
CORRECT
ANSWER-No
Can
we
determine
whether
a
deep
culture
is
pure
by
visually
inspecting
it
without
a
microscope?
-
CORRECT
ANSWER-No
Can
we
determine
whether
a
slant
culture
is
pure
by
visually
inspecting
it
without
a
microscope?
-
CORRECT
ANSWER-No
When
is
a
loop
preferable
for
transferring
bacteria?
-
CORRECT
ANSWER-A
loop
is
preferable
when
transferring
cultures
to
a
slant
or
a
broth.
When
is
a
needle
preferable
for
transferring
bacteria?
-
CORRECT
ANSWER-A
needle
is
preferable
when
making
deep
cultures.
What
is
the
purpose
of
flaming
the
loop
before
use?
-
CORRECT
ANSWER-To
sterilize
the
loop
from
environmental
microbes.
What
is
the
purpose
of
flaming
the
loop
after
use?
-
CORRECT
ANSWER-To
sterilize
the
loop
from
cultured
microbes.
Why
must
the
loop
be
cool
before
you
touch
it
to
a
culture?
-
CORRECT
ANSWER-A
hot
loop
would
heat
up
the
bacteria
enough
to
denature
and
kill
the
microbes. Should
you
set
the
loop
down
to
let
it
cool?
-
CORRECT
ANSWER-You
should
not
set
the
loop
down
to
cool
because
that
would
contaminate
it.
Why
is
aseptic
technique
important?
-
CORRECT
ANSWER-Minimizes
contamination
and
cross-contamination.
What
evolutionary
advantage
would
there
be
to
the
formation
of
a
pellicle
in
a
liquid
medium
by
a
bacterium?
-
CORRECT
ANSWER-It
would
provide
oxygen-loving
bacteria
with
the
ability
to
float
on
the
surface
of
the
liquid
and
form
aerobic
colonies.
How
can
you
tell
that
the
media
provided
for
this
exercise
were
sterile?
-
CORRECT
ANSWER-There
was
no
growth
prior
to
the
transfer
of
bacteria.
The
broth
was
clear
and
not
turbid.
Why
is
it
desirable
that
microscope
objectives
be
parfocal?
-
CORRECT
ANSWER-Because
parfocal
microscope
objectives
remain
focused
when
magnification
is
changed,
so
you
can
change
lenses
without
losing
focus.
Which
objective
focuses
closest
to
the
slide?
-
CORRECT
ANSWER-100x
oil
immersion
What
controls
the
amount
of
light
reaching
the
ocular
lens?
-
CORRECT
ANSWER-Iris
diaphragm
What
effect
does
increased
magnification
have
on
the
field
of
view?
-
CORRECT
ANSWER-As
the
magnification
increases,
the
field
of
view
decreases.
Name
two
ways
in
which
you
can
enhance
the
resolving
power.
-
CORRECT
ANSWER-1.)
Use
a
shorter
wavelength
of
light
2.)
Increase
numerical
aperture
What
advantage
does
the
low-power
objective
lens
have
over
the
immersion
objective
for
viewing
fungi?
-
CORRECT
ANSWER-It
provides
a
better
view
of
the
overall
shape
since
fungi
are
significantly
larger
than
bacteria. What
would
occur
if
water
were
accidentally
used
water
in
place
of
immersion
oil?
-
CORRECT
ANSWER-The
image
would
not
be
clear
because
the
immersion
oil
helps
bend
the
light
to
focus
correctly.
Of
what
value
is
a
simple
stain?
-
CORRECT
ANSWER-A
simple
stain
allows
you
to
see
the
size,
morphology,
and
arrangement
of
the
cells.
What
is
the
purpose
of
fixing
the
smear?
-
CORRECT
ANSWER-To
prevent
the
sample
from
being
lost
during
staining.
In
heat
fixing,
what
would
happen
if
too
much
heat
were
applied?
-
CORRECT
ANSWER-The
cells
could
be
denatured
and
may
lose
their
structural
integrity,
which
would
make
them
less
viewable
under
the
microscope.
The
glass
slide
could
crack
or
melt
with
enough
heat.
Methylene
blue
can
be
prepared
as
a
basic
stain
or
an
acidic
stain.
How
would
the
pH
effect
the
staining
of
bacteria.
-
CORRECT
ANSWER-The
bacteria
can
only
be
stained
by
a
dye
with
a
charge
opposite
their
own.
An
acidic
dye's
negative
charge
would
be
repelled
by
the
negative
charges
of
the
bacterial
cell.
Can
dyes
other
than
methylene
blue
be
used
for
direct
staining?
-
CORRECT
ANSWER-Yes,
any
dye
that
can
be
prepared
as
a
basic
stain
could
be
used
because
the
stain
can
permeate
the
cell
wall
and
adhere
by
weak
ionic
bonds
to
the
negative
charges
of
the
bacterial
cell.
Bacteria
can
be
seen
without
staining.
Why
then
was
Koch's
recommendation
for
fixing
and
staining
important
for
microbiology?
-
CORRECT
ANSWER-Fixing
kills
the
bacteria
without
distorting
their
shape.
This
allows
us
to
see
structure
and
later
allowed
us
to
see
things
like
gram
stain.
What
types
of
dyes
are
used
for
negative
staining?
-
CORRECT
ANSWER-Dyes
with
a
negative
charge,
because
they
are
repelled
by
the
negative
cell
wall
and
dye
the
background
instead
of
the
cells.
What
microscopic
technique
gives
a
field
similar
in
appearance
to
that
seen
in
the
negative
stain?
-
CORRECT
ANSWER-Dark
field
microscopy