Microbiology Lab Practical 1 (Pearson
Education Edition) Exam Questions
and Answers 100% Pass
What bacterial shape is observed? - ✔✔Bacillus
What bacterial shape is observed? - ✔✔Coccus
What bacterial shape is observed? - ✔✔Spiral/spirochete
How does increase in magnification affect field of vision? - ✔✔It makes it smaller
How does increased magnification affect depth of field? - ✔✔Depth of field becomes
larger
Why is it desirable that microscope objectives be parfocal? - ✔✔So each objective does
not require further focusing
Which objective focuses the closest to the slide when it is in focus? - ✔✔The dry-oil / oil
lens objective
Which controls on the microscope affect the amount of light reaching the ocular lens? -
✔✔The rheostat and the diaphragm
Katelyn Whitman, All Rights Reserved © 2025 1
,Assume the diameter of the field of vision in your microscope is 2mm under low power.
If one Bacillus cell measures 2 um, how many Bacillus cells could fit end-to-end across
the field? - ✔✔2,000 Bacillus cells at 2mm low power
How many 10 um yeast cells could fit across the field? - ✔✔200 yeast cells at 2mm low
power
What are the advantages of the low-power objective over the oil immersion / dry-oil
objective for viewing fungi or algae? - ✔✔The organism can be viewed in its entirety,
rather than being limited to only one area and one plane at a time.
What would occur if water were accidentally used in place of oil immersion / dry oil? -
✔✔It would act as another lens and distort the focusing power, or distort the image
being viewed.
Assume you are looking for microorganisms in a tissue sample from a lung biopsy. The
microbes become apparent when you switch to 1000X. What type of microbe is most
likely? - ✔✔Bacteria (because it is a prokaryote, and they are much smaller, and
therefore much more difficult to see at lower powers under the microscope)
What is Brownian movement? - ✔✔Movement caused by the molecules in the liquid
striking an object and causing that object to bounce.
What is true motility? - ✔✔Motile microorganisms are able to move from one position
to another of their own accord.
Katelyn Whitman, All Rights Reserved © 2025 2
, How do you distinguish true motility from Brownian movement or motion of the fluid?
- ✔✔True motility has purposeful movement. Brownian movement consists mostly of
shaking.
What, if any, practical value do the wet mount and hanging drop techniques have? -
✔✔Allows the viewing of activity of living cells, how they move, and interact with their
environment.
Why are microorganisms hard to see in wet preparations? - ✔✔The microorganisms
have not been dyed, and so, since they do not have any color to them, they do not
contrast against the environment.
Can you distinguish the prokaryotic organisms from the eukaryotic organisms?
Explain. - ✔✔Yes, prokaryotic organisms are much smaller, have no membranous
organelles, nor a nucleus. Eukaryotic organisms are much larger, have membrane
bound organelles, and a nucleus.
A wet mount may be used for quick examination of fecal samples. Is this the most
useful for identifying protozoan or bacterial parasites? - ✔✔This is most useful for
identifying protozoan parasites because they are eukaryotic and therefore much larger
than bacterial parasites, and can be more easily viewed without a stain.
What is the advantage of using Petri plates rather than test tubes in microbiology? -
✔✔Petri plates allow for the viewing of colonies, allowing visual differentiation of
Katelyn Whitman, All Rights Reserved © 2025 3
Education Edition) Exam Questions
and Answers 100% Pass
What bacterial shape is observed? - ✔✔Bacillus
What bacterial shape is observed? - ✔✔Coccus
What bacterial shape is observed? - ✔✔Spiral/spirochete
How does increase in magnification affect field of vision? - ✔✔It makes it smaller
How does increased magnification affect depth of field? - ✔✔Depth of field becomes
larger
Why is it desirable that microscope objectives be parfocal? - ✔✔So each objective does
not require further focusing
Which objective focuses the closest to the slide when it is in focus? - ✔✔The dry-oil / oil
lens objective
Which controls on the microscope affect the amount of light reaching the ocular lens? -
✔✔The rheostat and the diaphragm
Katelyn Whitman, All Rights Reserved © 2025 1
,Assume the diameter of the field of vision in your microscope is 2mm under low power.
If one Bacillus cell measures 2 um, how many Bacillus cells could fit end-to-end across
the field? - ✔✔2,000 Bacillus cells at 2mm low power
How many 10 um yeast cells could fit across the field? - ✔✔200 yeast cells at 2mm low
power
What are the advantages of the low-power objective over the oil immersion / dry-oil
objective for viewing fungi or algae? - ✔✔The organism can be viewed in its entirety,
rather than being limited to only one area and one plane at a time.
What would occur if water were accidentally used in place of oil immersion / dry oil? -
✔✔It would act as another lens and distort the focusing power, or distort the image
being viewed.
Assume you are looking for microorganisms in a tissue sample from a lung biopsy. The
microbes become apparent when you switch to 1000X. What type of microbe is most
likely? - ✔✔Bacteria (because it is a prokaryote, and they are much smaller, and
therefore much more difficult to see at lower powers under the microscope)
What is Brownian movement? - ✔✔Movement caused by the molecules in the liquid
striking an object and causing that object to bounce.
What is true motility? - ✔✔Motile microorganisms are able to move from one position
to another of their own accord.
Katelyn Whitman, All Rights Reserved © 2025 2
, How do you distinguish true motility from Brownian movement or motion of the fluid?
- ✔✔True motility has purposeful movement. Brownian movement consists mostly of
shaking.
What, if any, practical value do the wet mount and hanging drop techniques have? -
✔✔Allows the viewing of activity of living cells, how they move, and interact with their
environment.
Why are microorganisms hard to see in wet preparations? - ✔✔The microorganisms
have not been dyed, and so, since they do not have any color to them, they do not
contrast against the environment.
Can you distinguish the prokaryotic organisms from the eukaryotic organisms?
Explain. - ✔✔Yes, prokaryotic organisms are much smaller, have no membranous
organelles, nor a nucleus. Eukaryotic organisms are much larger, have membrane
bound organelles, and a nucleus.
A wet mount may be used for quick examination of fecal samples. Is this the most
useful for identifying protozoan or bacterial parasites? - ✔✔This is most useful for
identifying protozoan parasites because they are eukaryotic and therefore much larger
than bacterial parasites, and can be more easily viewed without a stain.
What is the advantage of using Petri plates rather than test tubes in microbiology? -
✔✔Petri plates allow for the viewing of colonies, allowing visual differentiation of
Katelyn Whitman, All Rights Reserved © 2025 3
