Microbiology LAB Exam #1 Questions
and Answers 100% Pass
Microscope- The Condenser - ✔✔focuses the light ging into the objective lens
Microscope- The Iris Diaphragm - ✔✔adjusts the amount of light going into the
objective lens
Microscope- Nosepiece - ✔✔holds the objective lenses and rotates to change from one
objective to another
Microscope- Coarse Objective Knob - ✔✔moves the stage larger distances to help get
the object in focus
Microscope- Fine Adjustment Knob - ✔✔moves the stage smaler increments to help get
the object in better focus
Microscope- Objective Lens - ✔✔magnifies the object. It is located near the object.
Microscope- Occular Lens - ✔✔magnifies the image of the object from the objective lens.
It is located near the eye.
Steps in using the microscope - ✔✔1) scanner power in place
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,2) place slide of specimen stage in place with stage clips
3) Using the course adjustment knob, raise the stage all the way up and then down
slowly until you can see image of specimen
4) Readjust with fine adjustment knob
Describe the purpose of the oil immersion lens - ✔✔Used when oil is added to the slide.
Oil must touch the object and objective lens to that the light does not refract futher
Parfocal - ✔✔Parfocal microscopes are able to move from one objective to the next and
still be in focus due to the length of the objective lenses
Resolution - ✔✔The ability to distinguish between two objects that are very close
together.
What is resolving power? - ✔✔The measurement of resolution
What are two ways to increase resolving power? - ✔✔1. By decreasing the wavelength
of light (using a blue filter) 2. Increasing the numerical aperature
What units are used to express resolving power? - ✔✔nm or nanometers
What is better, smaller or larger resolving power? - ✔✔Smaller is better
Light microscopes have a 200nm resolving power
Electron microscopes have a .2nm resolving power
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, What is chromatic aberration? - ✔✔The effect when many colors are seen toward the
edge of the microscope field of vision (like a prisim)
How are microscopes corrected for chromatic aberration? - ✔✔With a special
achromatic lens (corrected for red and blue light) or by using a blue filter. The lab has
blue filters in their microscopes which also increase resolution.
Describe the process of making a wet-mount slide - ✔✔1) Add the specimen to the slide
2) Touch the edge of the cover slip with one edge of drop of specimen.
3) Let the cover slip drop gradually to the slide, covering the drop of specimen.
Describe the purpose of making a wet-mount slide - ✔✔To be able to see living
organisms under the microscope in their natural state.
What is the advantage of using a wet-mount slide? - ✔✔Can see movement and
determine if microbes posses their own method of motility. Can also see the actual
shape and arrangement of microbes.
What is the dis-advantage of using a wet-mount slide? - ✔✔The movement is very fast,
microbes are transparent. Must use a "dark-field stop".
What is a producer? - ✔✔Are autotroph organisms that make their own food (through
photosynthesis).
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and Answers 100% Pass
Microscope- The Condenser - ✔✔focuses the light ging into the objective lens
Microscope- The Iris Diaphragm - ✔✔adjusts the amount of light going into the
objective lens
Microscope- Nosepiece - ✔✔holds the objective lenses and rotates to change from one
objective to another
Microscope- Coarse Objective Knob - ✔✔moves the stage larger distances to help get
the object in focus
Microscope- Fine Adjustment Knob - ✔✔moves the stage smaler increments to help get
the object in better focus
Microscope- Objective Lens - ✔✔magnifies the object. It is located near the object.
Microscope- Occular Lens - ✔✔magnifies the image of the object from the objective lens.
It is located near the eye.
Steps in using the microscope - ✔✔1) scanner power in place
Katelyn Whitman, All Rights Reserved © 2025 1
,2) place slide of specimen stage in place with stage clips
3) Using the course adjustment knob, raise the stage all the way up and then down
slowly until you can see image of specimen
4) Readjust with fine adjustment knob
Describe the purpose of the oil immersion lens - ✔✔Used when oil is added to the slide.
Oil must touch the object and objective lens to that the light does not refract futher
Parfocal - ✔✔Parfocal microscopes are able to move from one objective to the next and
still be in focus due to the length of the objective lenses
Resolution - ✔✔The ability to distinguish between two objects that are very close
together.
What is resolving power? - ✔✔The measurement of resolution
What are two ways to increase resolving power? - ✔✔1. By decreasing the wavelength
of light (using a blue filter) 2. Increasing the numerical aperature
What units are used to express resolving power? - ✔✔nm or nanometers
What is better, smaller or larger resolving power? - ✔✔Smaller is better
Light microscopes have a 200nm resolving power
Electron microscopes have a .2nm resolving power
Katelyn Whitman, All Rights Reserved © 2025 2
, What is chromatic aberration? - ✔✔The effect when many colors are seen toward the
edge of the microscope field of vision (like a prisim)
How are microscopes corrected for chromatic aberration? - ✔✔With a special
achromatic lens (corrected for red and blue light) or by using a blue filter. The lab has
blue filters in their microscopes which also increase resolution.
Describe the process of making a wet-mount slide - ✔✔1) Add the specimen to the slide
2) Touch the edge of the cover slip with one edge of drop of specimen.
3) Let the cover slip drop gradually to the slide, covering the drop of specimen.
Describe the purpose of making a wet-mount slide - ✔✔To be able to see living
organisms under the microscope in their natural state.
What is the advantage of using a wet-mount slide? - ✔✔Can see movement and
determine if microbes posses their own method of motility. Can also see the actual
shape and arrangement of microbes.
What is the dis-advantage of using a wet-mount slide? - ✔✔The movement is very fast,
microbes are transparent. Must use a "dark-field stop".
What is a producer? - ✔✔Are autotroph organisms that make their own food (through
photosynthesis).
Katelyn Whitman, All Rights Reserved © 2025 3
