Microbiology Lab Practical 1 (Pearson
Education Edition)- Questions & Answers
What bacterial shape is observed? Correct Ans-Bacillus
What bacterial shape is observed? Correct Ans-Coccus
What bacterial shape is observed? Correct Ans-Spiral/spirochete
How does increase in magnification affect field of vision? Correct Ans-It makes it smaller
How does increased magnification affect depth of field? Correct Ans-Depth of field becomes
larger
Why is it desirable that microscope objectives be parfocal? Correct Ans-So each objective
does not require further focusing
Which objective focuses the closest to the slide when it is in focus? Correct Ans-The dry-oil /
oil lens objective
Which controls on the microscope affect the amount of light reaching the ocular lens? Correct
Ans-The rheostat and the diaphragm
,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?
Correct Ans-2,000 Bacillus cells at 2mm low power
How many 10 um yeast cells could fit across the field? Correct Ans-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? Correct Ans-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? Correct
Ans-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? Correct
Ans-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? Correct Ans-Movement caused by the molecules in the liquid
striking an object and causing that object to bounce.
What is true motility? Correct Ans-Motile microorganisms are able to move from one
position to another of their own accord.
, How do you distinguish true motility from Brownian movement or motion of the fluid?
Correct Ans-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? Correct
Ans-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? Correct Ans-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.
Correct Ans-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? Correct Ans-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? Correct
Ans-Petri plates allow for the viewing of colonies, allowing visual differentiation of microbes
based on whole colony appearance, elevation, and the potential movement of the microorganism.
Education Edition)- Questions & Answers
What bacterial shape is observed? Correct Ans-Bacillus
What bacterial shape is observed? Correct Ans-Coccus
What bacterial shape is observed? Correct Ans-Spiral/spirochete
How does increase in magnification affect field of vision? Correct Ans-It makes it smaller
How does increased magnification affect depth of field? Correct Ans-Depth of field becomes
larger
Why is it desirable that microscope objectives be parfocal? Correct Ans-So each objective
does not require further focusing
Which objective focuses the closest to the slide when it is in focus? Correct Ans-The dry-oil /
oil lens objective
Which controls on the microscope affect the amount of light reaching the ocular lens? Correct
Ans-The rheostat and the diaphragm
,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?
Correct Ans-2,000 Bacillus cells at 2mm low power
How many 10 um yeast cells could fit across the field? Correct Ans-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? Correct Ans-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? Correct
Ans-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? Correct
Ans-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? Correct Ans-Movement caused by the molecules in the liquid
striking an object and causing that object to bounce.
What is true motility? Correct Ans-Motile microorganisms are able to move from one
position to another of their own accord.
, How do you distinguish true motility from Brownian movement or motion of the fluid?
Correct Ans-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? Correct
Ans-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? Correct Ans-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.
Correct Ans-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? Correct Ans-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? Correct
Ans-Petri plates allow for the viewing of colonies, allowing visual differentiation of microbes
based on whole colony appearance, elevation, and the potential movement of the microorganism.
