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Homework Micro Chap 3

Olida Green avatar Olida Green
4 September 2022
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25 test answers

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question
Why is a specimen smaller than 200 nm not visible with a light microscope?
answer
Anything smaller than 200 nm cannot interact with visible light.
question
What happens to the light rays when they hit the specimen?
answer
They are reflected, refracted, or absorbed by the specimen.
question
What is the role of the ocular lens?
answer
To recreate the image in the viewer's eye
question
What is meant by light rays being divergent?
answer
It is spreading out
question
In a typical brightfield microscope (seen in the animation), at which point does magnification begin?
answer
The objective lens
question
Why do electron microscopes have higher resolving power than light microscopes?
answer
Electrons have a smaller wavelength than visible light, leading to higher resolution.
question
Which of the following is a lens found on electron microscopes but not on light microscopes?
answer
Projector lens
question
Which type of microscope would allow the viewer to see ribosomes inside a cell?
answer
A transmission electron microscope
question
Which of the following is a characteristic shared by both electron and light microscopes?
answer
They both employ the use of objective lenses.
question
What is the fate of the electrons that interact with a specimen in an electron microscope?
answer
They may be absorbed, reflected, or refracted by the specimen.
question
Which of the following measurements is correctly matched with microorganisms of that size?
answer
bacteria--2 micrometers
question
What does resolution mean?
answer
the ability of a microscope to distinguish fine details and differentiate between two very close objects
question
Which of the following describes the correct path of light in a compound light microscope, from the illumination source to the eye of the observer?
answer
illuminator ( condenser lenses ( specimen ( objective lenses ( body tube ( ocular lens ( eye
question
Which of the following statements comparing electron microscopy and light microscopy is FALSE?
answer
Both the electron microscope and the light microscope use the same wavelengths for illumination.
question
When an object is viewed through a light microscope with oculars that magnify 20x and a high-power objective lens that magnifies 100x, what is the total magnification of the object?
answer
2000x
question
Which of the following types of microscopy provides advantages for viewing live images?
answer
darkfield microscopy
question
What is the role of lenses in microscopy?
answer
Lenses focus either light or electrons to create a magnified image of a specimen.
question
While staining a mixed culture of Gram-positive and Gram-negative bacteria, switching the order of steps 2 and 3 would result in ______________________.
answer
all bacteria appearing pink
question
Which structural feature of Gram-positive bacteria enhances their ability to retain the crystal violet dye?
answer
a thick peptidoglycan layer
question
What would you anticipate seeing if you accidentally switched crystal violet and safranin while performing a Gram stain?
answer
All bacteria would appear purple.
question
What would you expect to see if you forgot to perform step 2 of the Gram stain procedure?
answer
All bacteria would appear pink.
question
What is the role of iodine in the Gram stain process?
answer
Iodine is a mordant in the Gram stain technique, which functions to intensify the primary stain.
question
A student creates a Gram stain on a bacterial specimen that has a mix of gram-negative and gram-positive organisms but accidentally forgets the decolorizer step. What would the outcome of the Gram stain be?
answer
All organisms would appear purple (gram-positive).
question
Consider the following situations, and determine when a simple stain could be used instead of a Gram stain.
answer
A microbiologist is trying to determine whether a specimen contains bacteria or fungi.
question
Which of the following staining procedures is matched with the principal use for that stain?
answer
acid-fast stain for microbes with waxy cell walls