Chapter 9: Assignment Questions COMPLETE

Question 1

Color is a feature of:

objects that are smaller than the wavelength of visible light

objects that are larger than the shortest wavelength of visible light

Answer 1

objects that are larger than the shortest wavelength of visible light

Question 2

A nanometer (nm) is:

10^-4 meters (m)
10^-9 m
10^-6 m
10^-10 m

Answer 2

10^-9 m

Question 3

Can light microcopy DETECT an object that is less than 200 nm in diameter?

yes…but the image will be a blur
no

Answer 3

yes…but the image will be a blur

Question 4

Can conventional light microscopy RESOLVE two objects that are less than 200 nm apart?

yes
no

Answer 4

no

Question 5

The greater the numerical aperture (n sin theta), the ________ the resolution.

better (i.e. can resolve objects that are closer together)

worse (i.e. objects need to be farther apart to resolve

Answer 5

better (i.e. can resolve objects that are closer together)

Question 6

Which gives a higher value for “numerical aperture?”

oil
air

Answer 6

oil

Question 7

The longer the wavelength of the light from a microscope’s light source, the ________ the resolution.

better (i.e. can resolve objects that are closer together)
worse (i.e. objects need to be farther apart to resolve

Answer 7

worse (i.e. objects need to be farther apart to resolve

Question 8

Noise in a light image refers to:

the numerical aperture

the resolution limit

the wavelength of light

random fluctuations in the distribution of photons that pass through a specimen

Answer 8

random fluctuations in the distribution of photons that pass through a specimen

Question 9

Which is NOT a good way to visualize living cells?

dark field microcopy
differential interference contrast microscopy
phase contrast microscopy
light microscopy of fixed and stained specimens

Answer 9

light microscopy of fixed and stained specimens

Question 10

Which is the best (of the following) way to distinguish among different features of a cell?

dark field microcopy
differential interference contrast microscopy
phase contrast microscopy
light microscopy of fixed and stained specimens

Answer 10

light microscopy of fixed and stained specimens

Question 11

A dye such as hematoxylin that has affinity for negatively-charged macromolecules can reveal the subcellular localization of:

DNA

RNA

proteins with many acidic (negatively charged at physiological pH) side chains

All of those negatively-charged macromolecules listed above

Answer 11

All of those negatively-charged macromolecules listed above

Question 12

In situ hybridization would best be used to detect specific:

RNAs
DNA
protein
structural carbohydrates

Answer 12

RNAs

Question 13

In situ hybridization would probably use probes made of:

DNA (because it’s much more stable than RNA)
RNA
protein

Answer 13

DNA (because it’s much more stable than RNA)

Question 14

Fluorescence microscopy could be used to detect a specific protein if:

the protein of interest has been expressed with a fluorescent domain, such as that of green fluorescent protein

an antibody that specifically binds the protein of interest is attached to a fluorophore (a fluorescent compound)

both of the above!

Answer 14

both of the above!

Question 15

Generally, the types of fluorescent probes used in fluorescence microscopy:

absorb and emit light in the same wavelength

absorb light and then emit light at shorter wavelength

absorb light and then emit light at a longer wavelength

Answer 15

absorb light and then emit light at a longer wavelength

Question 16

In fluorescence microscopy, light is generally thought of as being excitation light or emitted light. The light that is absorbed by a fluorophore, leading to its later emission of light is the:

excitation light
emission light

Answer 16

excitation light

Question 17

In indirect
immunocytochemistry, the “marker molecule” that can lead to detection is attached to:

a primary antibody that directly binds a specific antigen (e.g. protein or other cellular component)

a secondary antibody that binds to a primary antibody that binds a specific antigen

Answer 17

a secondary antibody that binds to a primary antibody that binds a specific antigen

Question 18

Confocal microscopy produces optical sections of a specimen by

excluding out-of-focus light

using image processing to “deblurr” or “deconvolute” a series of images

Answer 18

excluding out-of-focus light

Question 19

Which would cause the least amount of damage to a specimen and allow imaging more deeply into the specimen?

ultraviolet light
visible light
infrared light in two-photon applications

Answer 19

infrared light in two-photon applications

Question 20

In FRET imaging, absorbance of _______ wavelength light by one component of the detection system and transfer of the energy to the second component leads to emission of light of a ___________ wavelength.

shorter; longer
shorter; similar
longer; shorter
longer; similar

Answer 20

shorter; longer

Question 21

FRET imaging gives a signal if:

the two components are close together
the two components are far apart

Answer 21

the two components are close together

Question 22

Fluorescence recovery after photobleaching is a way to detect:

proximity of two proteins

movement of tagged proteins or other tagged molecules into the area that had been bleached

3D structure

Answer 22

movement of tagged proteins or other tagged molecules into the area that had been bleached

Question 23

Which method is used to detect only targets that are very close to the surface of a cover slip?

TIRF
FRAP
image deconvolution
confocal microscopy
FRET

Answer 23

TIRF

Question 24

Switching fluorophores off and on sequentially in different regions of a specimen over time can lead to pin-point localization of cellular components such as proteins, giving _______ resolution than conventional or confocal fluorescence microscopy.

better
worse

Answer 24

better

Question 25

The wavelength of an electron in an electron microscope with an accelerating voltage of 100,000 volts is about 0.002 nm. So, visible light with a wavelength of 400 nm has a ___________ longer wavelength than the wavelength of electrons in this example.

10-fold
20-fold
2,000-fold
20,000-fold
200,000-fold

Answer 25

200,000-fold

Question 26

So, an electron microscope has ___________ resolution than a light microscope.

much better (i.e. resolves objects that are closer together)

much worse

Answer 26

much better (i.e. resolves objects that are closer together)

Question 27

In practice, the practical resolution of an electron microscope for biological objects is about 1 nm because of:

problems with specimen preparation

contrast with a specimen

damage to the specimen from high-velocity electrons

all of the above

Answer 27

all of the above

Question 28

So, the practical resolution for electron microscopy is about _________ times better than microscopy using light with a 200 nm wavelength.

200 times!
200,000 times
100,000 times

Answer 28

100,000 times

Question 29

A beam of electrons travels through a specimen in:

scanning electron microscopy

transmission electron microscopy

Answer 29

transmission electron microscopy

Question 30

Immunogold microscopy would be appropriate for:

light microscopy
fluorescence microscopy
electron microscopy
confocal microscopy

Answer 30

electron microscopy

Question 31

Three dimensional images of a specimen can be obtained by:

multiple TEM images taken at slightly different angles and then combined by image processing (EM tomography)

scanning electron microscopy

both!

Answer 31

multiple TEM images taken at slightly different angles and then combined by image processing (EM tomography)

Question 32

Taking images (maybe thousands) of many identical molecules and then combining them to produce an averaged image is:

single particle reconstruction
scanning electron microscopy
EM tomography

Answer 32

single particle reconstruction