2025 Lab Practical Questions and Answers A+
1.What technique is used to prevent contamination of cultures in the
labora- tory?: Aseptic technique
2.Bacterial cultures need to be placed into for use in the
spectropho- tometer.: cuvettes
3.The growth curve of bacteria shows a steep increase during the phase-
: exponential (log)
4.Pour plating can be used for which of the following?
-Obtaining isolated colonies for making pure cultures.
-Growing bacteria in a semisolid medium for observation of motility.
-Making samples for readings on a spectrophotometer.
-Culturing bacteria on top of and within the agar.: -Obtaining isolated
colonies for making pure cultures.
-Culturing bacteria on top of and within the agar.
5.Once the inoculated agar in the tubes is poured into the plates, they
should immediately be placed in the incubator.
True or False: False
6.Which of the following accurately describes a successful pour plate?
-Lumpy agar surface with colonies on the surface and within the agar.
-Smooth agar surface with colonies only on the surface.
-Smooth agar surface with colonies on the surface and within the agar.
-Lumpy agar surface with subsurface colonies only.: Smooth agar surface
with colonies on the surface and within the agar.
7.After subculturing one colony on a mixed isolation plate to a sterile
,slant, what should be the result?
-A slant with one type of bacteria growing.
-A slant with complete isolation of colonies on the surface.
-A slant with no growth.
-A slant with mixed bacterial types.: A slant with one type of bacteria
growing.
8.A net movement of water into the cells will occur.: Hypotonic Solution
9.There will be a net movement of water out of the cells.: Hypertonic Solutio
10.Human skin provides an environment with NaCl levels slightly above
that of most bacterial cells. Which organism would most likely be found on
the skin?
-Halobacterium sp.
-Staphylococcus aureus; a halotolerant organism
-E. coli; does not tolerate hypertonic salt conditions very well:
Staphylococcus aureus; a halotolerant organism
11.Which of the following may occur at temperatures below a
microorganism- ism's minimum growth temperature?
-Slowing of metabolic activity
-Denaturation of most enzymes
-Increased rate of metabolic reactions
-Membrane transport may be disrupted
-Decreased fluidity of the plasma membrane: -Slowing of metabolic activity
-Membrane transport may be disrupted
-Decreased fluidity of the plasma membrane
12.Which lens has a magnification of 4×?
, -Scanning objective
-High-power objective
-Oil immersion
-Low-power objective: Scanning objective
13.The portion of a slide that is visible through the eyepiece is called the
-field of view.
-real image.
-objective.
-stage.: field of view
14.The function of immersion oil in microscopy is to
-direct more light rays to the objective lens.
-increase the viscosity on the objective lens.
-immobilize the specimen on the slide.
-prevent the cover glass from reflecting light rays.: direct more light rays to
the objective lens
15.How does the increased contrast that results from staining aid in
visualiz- ing cells under the microscope?
-It aids in identification of the specific species being observed.
-It helps set them apart from the background.
-It increases magnification by 10 times.
-It alters the wavelength of light thus increasing magnification.: It helps set
them apart from the background.
16.A bacterial smear is created by spreading a thin layer of bacteria
across the surface of a slide.: True
17.The purpose of heat fixation is to
1.What technique is used to prevent contamination of cultures in the
labora- tory?: Aseptic technique
2.Bacterial cultures need to be placed into for use in the
spectropho- tometer.: cuvettes
3.The growth curve of bacteria shows a steep increase during the phase-
: exponential (log)
4.Pour plating can be used for which of the following?
-Obtaining isolated colonies for making pure cultures.
-Growing bacteria in a semisolid medium for observation of motility.
-Making samples for readings on a spectrophotometer.
-Culturing bacteria on top of and within the agar.: -Obtaining isolated
colonies for making pure cultures.
-Culturing bacteria on top of and within the agar.
5.Once the inoculated agar in the tubes is poured into the plates, they
should immediately be placed in the incubator.
True or False: False
6.Which of the following accurately describes a successful pour plate?
-Lumpy agar surface with colonies on the surface and within the agar.
-Smooth agar surface with colonies only on the surface.
-Smooth agar surface with colonies on the surface and within the agar.
-Lumpy agar surface with subsurface colonies only.: Smooth agar surface
with colonies on the surface and within the agar.
7.After subculturing one colony on a mixed isolation plate to a sterile
,slant, what should be the result?
-A slant with one type of bacteria growing.
-A slant with complete isolation of colonies on the surface.
-A slant with no growth.
-A slant with mixed bacterial types.: A slant with one type of bacteria
growing.
8.A net movement of water into the cells will occur.: Hypotonic Solution
9.There will be a net movement of water out of the cells.: Hypertonic Solutio
10.Human skin provides an environment with NaCl levels slightly above
that of most bacterial cells. Which organism would most likely be found on
the skin?
-Halobacterium sp.
-Staphylococcus aureus; a halotolerant organism
-E. coli; does not tolerate hypertonic salt conditions very well:
Staphylococcus aureus; a halotolerant organism
11.Which of the following may occur at temperatures below a
microorganism- ism's minimum growth temperature?
-Slowing of metabolic activity
-Denaturation of most enzymes
-Increased rate of metabolic reactions
-Membrane transport may be disrupted
-Decreased fluidity of the plasma membrane: -Slowing of metabolic activity
-Membrane transport may be disrupted
-Decreased fluidity of the plasma membrane
12.Which lens has a magnification of 4×?
, -Scanning objective
-High-power objective
-Oil immersion
-Low-power objective: Scanning objective
13.The portion of a slide that is visible through the eyepiece is called the
-field of view.
-real image.
-objective.
-stage.: field of view
14.The function of immersion oil in microscopy is to
-direct more light rays to the objective lens.
-increase the viscosity on the objective lens.
-immobilize the specimen on the slide.
-prevent the cover glass from reflecting light rays.: direct more light rays to
the objective lens
15.How does the increased contrast that results from staining aid in
visualiz- ing cells under the microscope?
-It aids in identification of the specific species being observed.
-It helps set them apart from the background.
-It increases magnification by 10 times.
-It alters the wavelength of light thus increasing magnification.: It helps set
them apart from the background.
16.A bacterial smear is created by spreading a thin layer of bacteria
across the surface of a slide.: True
17.The purpose of heat fixation is to
