Deck 3: Microscopy and Staining

Question 1

When light passes through an object,________ of the light has occurred.

A)reflection
B)absorption
C)transmission
D)fluorescence

Answer 1

C

Question 2

What is true about the index of refraction?

A)If light rays are taken up by the object than it has a high index of refraction.
B)Refraction measures the frequency of the light as it reflects from a material.
C)Oil immersion lenses increase the problem of refraction.
D)Light will bend as it passes through two substances with different indices of refraction.

Answer 2

D

Question 3

A compound light microscope can generally see objects as no smaller than a _____.

A)ribosome
B)large protozoa
C)small bacterium
D)typical virus

Answer 3

C

Question 4

Which of the following statements about Leeuwenhoek's microscopes is false?

A)Leeuwenhoek kept his technique secret.
B)They magnified objects 100 to 300 times.
C)For each specimen a new microscope had to be made.
D)They were able to reveal very fine details of bacteria.

Question 5

Which of the following statements about resolution is true?

A)Resolution refers to the ability of a lens to distinguish adjacent objects.
B)With regard to light, resolution means the same thing as wavelength.
C)Resolution refers to a microscope's ability to magnify objects.
D)Resolution is equal to the distance between two adjacent crests of a wave.

Question 6

The formula for the resolving power (resolution distance)of a lens is ƛ/2NA (wavelength /2 x numerical aperture). What does this say about resolving power?

A)The smaller the wavelength, the greater the resolving power of the lens.
B)Resolving power is not related to the lens' numerical aperture.
C)We cannot precisely calculate a lens' resolving power.
D)A larger resolving power is indicative of a better lens.

Question 7

Most light microscopes contain a/an ________ that converges the light beam so that it passes through the specimen.

A)objective lens
B)iris diaphragm
C)mechanical stage
D)condenser

Question 8

Why is diffraction a problem for microscopy?

A)The lens acts as a large aperture through which light must pass.
B)The small size of higher-power lenses causes severe diffraction.
C)The loss of light results in blurred images.
D)Diffraction of light is useful when using an oil immersion lens to view objects.

Question 9

During microscopic observation of a specimen,the amount of light that is allowed to pass through the specimen is controlled by the:

A)condenser
B)objective lens
C)iris diaphragm
D)ocular lens

Question 10

The lens closest to the slide during a microscopic examination is the _____.

A)ocular
B)objective
C)condenser
D)compound

Question 11

A compound microscope has _____.

A)two eyepieces
B)a total magnification of 5,000X
C)only fine adjustment and no coarse adjustment
D)more than one lens

Question 12

To calculate the total magnification of a light microscope you must know the magnification of the _____ lenses.

A)objective and condenser
B)ocular and condenser
C)objective and condenser
D)objective and ocular

Question 13

In order to make use of light for a microscopic examination of an object the object must ________ or ________ light.

A)absorb, luminesce
B)transmit, absorb
C)transmit, reflect
D)reflect, absorb

Question 14

The total magnification of a specimen being viewed with a 10X ocular lens and a 40X objective lens is _____.

A)4X
B)40X
C)400X
D)4000X

Question 15

Electron microscopes have a much better resolving power when compared to light microscopes because electrons _____.

A)are invisible to the eye
B)have longer wavelengths than visible light rays
C)have shorter wavelengths than visible light rays
D)are negatively charged

Question 16

Light of ________ wavelength typically will result in ________ resolution.

A)longer, better
B)shorter, better
C)any, poor
D)shorter, worse

Question 17

The lens closest to your eyes during a microscopic examination is the _____.

A)ocular
B)objective
C)condenser
D)compound

Question 18

When light rays pass into an object but do not emerge,________ has taken place.

A)reflection
B)absorption
C)refraction
D)transmission

Question 19

Diffraction occurs when light _____.

A)is reflected by an object
B)passes through a small opening
C)changes wavelengths
D)is absorbed by a normally transparent object (like a glass slide)

Question 20

When light bends as it passes through an object,________ of the light has occurred.

A)reflection
B)absorption
C)transmission
D)refraction

Question 21

A parfocal microscope:

A)has more than one source of illumination
B)has both coarse and fine focusing adjustment
C)accentuates small differences in the refractive index of intracellular structures
D)allows for specimens to remain in focus when changing between magnification

Question 22

Transmission electron microscopes have a maximum magnification of _____.

A)1,000X
B)100,000X
C)500,000X
D)1,000,000X

Question 23

Three dimensional views of cells and other small objects could best be obtained using a:

A)phase contrast microscope
B)dark-field microscope
C)transmission electron microscope (TEM)
D)scanning electron microscope (SEM)

Question 24

Atomic force microscope:

A)allows 3 dimensional imaging and measurement of structures as small as nucleotides in DNA
B)is not yet capable of measuring small forces
C)involves ultraviolet light exciting molecules so that they release light of a longer wavelength
D)has a special condenser and objective lens

Question 25

Which of the following is not a differential stain?

A)Gram stain
B)Schaeffer-Fulton
C)acid-fast stain
D)flagellar stain

Question 26

Electron microscopes:

A)that are scanning have better resolution than those that are transmission
B)are much more expensive and take up more space than light microscopes
C)can use the same preparations of specimens that have been prepared for viewing with a light microscope
D)have a resolving power approximately 10 times better than the best light microscope

Question 27

In a Gram stain,the mordant is _____.

A)crystal violet
B)iodine
C)water
D)alcohol

Question 28

A simple stain:

A)uses only a single dye.
B)requires only one step to stain a slide.
C)distinguishes between two different parts of an organism.
D)is composed of an equal balance of acidic and basic dyes.

Question 29

The term "basic dyes" refers to the fact that these dyes are _____.

A)easily prepared
B)positively charged
C)attracted to positively charged cell structures
D)simple in their composition

Question 30

The advent of the electron microscope allowed ________ to be viewed for the first time.

A)protozoa
B)bacteria
C)viruses
D)algae

Question 31

The best electron microscopes have a resolution of _____ nm.

A)0.1
B)1
C)10
D)100

Question 32

Which of the following can be used to examine live specimens?

A)TEM
B)SEM
C)scanning tunneling electron microscope
D)atomic force microscope

Question 33

Electron microscopes use ________ to focus the electron beam.

A)glass lenses
B)electromagnets
C)mechanical stages
D)laser beams

Question 34

Which of the following statements about preparing a light microscope specimen is false?

A)Organisms must be heat fixed before being viewed in a hanging drop slide.
B)Smears are loopfuls of medium spread on the surface of a glass slide.
C)Wet mount preparations give good views of microbial mobility.
D)The depth of a smear affects the results; if too thin you may find no organisms.

Question 35

Colored photos of electron micrographs:

A)reflect the color of the specimen before it was frozen
B)are false color added on during image preparation
C)reflect the color of the specimen after it was frozen
D)are always in pastel shades

Question 36

A microscope in which light rays pass directly through a specimen is a ________ microscope.

A)bright field
B)dark field
C)phase-contrast
D)Nomarski

Question 37

Ultraviolet light is a key component of:

A)bright-field microscopy
B)dark-field microscopy
C)phase-contrast microscopy
D)fluorescence microscopy

Question 38

A microscope that converts changes in the speed of light as it passes through an object into differences in brightness is a ________ microscope.

A)bright field
B)dark field
C)phase-contrast
D)Nomarski

Question 39

Which is a false statement about light microscopy?

A)A dark-field microscope produces bright images against a dark background.
B)A phase contrast microscope gives 3-dimensional images.
C)Fluorescent antibody staining cannot determine whether a foreign organism such as a microbe is present in a specimen.
D)A Nomarski microscope produces much higher resolution than the standard phase-contrast microscope.

Question 40

The technique that involves the evaporation of water from a frozen and fractured specimen is called:

A)shadow casting
B)freeze-etching
C)heat fixation
D)freeze-fracturing

Question 41

If the step involving iodine were left out of a Gram stain,which of the following would best describe the results?

A)Gram negative cells would look Gram positive.
B)Gram positive cells would look Gram negative.
C)All rods would be pink, all cocci purple.
D)All cells would be purple.

Question 42

Would light of a shorter or longer wavelength give you better resolution when using a microscope? Why? Would a light microscope that had a total magnification of 500X give you better resolution as one that has a magnification of 100X? Why?

Question 43

Which of the following stains has been used on this microorganism?

A)Flagellar stain
B)Capsule stain
C)Endospore stain
D)No stain

Question 44

What statement about microscopy and staining techniques is false?

A)Many species look identical under the microscope.
B)Staining and microscopic examination are usually all that is need to identify a microorganism.
C)Microscopes are of little use unless the specimens are prepared properly.
D)The degree of contrast is equally important as resolution and magnification.

Question 45

Which stain would be the best choice for detecting mycobacterium (the bacteria responsible for tuberculosis and leprosy)?

A)simple stain
B)endospore stain
C)acid-fast stain
D)Gram stain

Question 46

What is the Gram stain? What does it distinguish?

Question 47

The image of this fungus was taken using a:

A)confocal microscope
B)atomic force microscope
C)compound light microscope
D)fluorescence microscope

Question 48

In a properly executed Gram stain,Gram positive organisms appear ________ while Gram negative organisms appear ________.

A)pink, clear
B)pink, purple
C)purple, pink
D)purple, blue

Question 49

Compare and contrast light microscopy and electron microscopy.Be sure to include how they work and what they can see (or the extent of their total magnification).

Question 50

Suitable stains for use in the Ziehl-Neelsen acid-fast stain are _____.

A)crystal violet and eosin
B)carbolfuschin and methylene blue
C)carbolfuschin and safranin
D)safranin and methylene blue

Question 51

Why do basic dyes attach to most bacterial surfaces?

A)Most bacterial surfaces are negatively charged.
B)Bacterial cells take up safranin.
C)Most bacterial surfaces resist taking up the stain.
D)Most bacterial surfaces do not have a charge.

Question 52

The counterstain in the endospore stain is _____.

A)malachite green
B)crystal violet
C)safranin
D)methylene blue

Question 53

When given a microorganism to identify,which of the following would be useful?

A)A Gram stain
B)A transmission electron micrograph
C)Biochemical and genetic characteristics
D)All of the above

Question 54

Which type of staining results in a clear object being viewed against a dark background?

A)Simple stain
B)Negative stain
C)Endospore stain
D)Flagellar stain

Question 55

This structure converges the light beams so they pass through the specimen.

A)A
B)B
C)C
D)D

Question 56

Bacterial capsules can best be visualized by _______ staining.

A)flagellar
B)crystal violet
C)negative
D)mordant