Quiz about BIOL 221 L4

Question 1

What type of microscope views a specimen with light reflected from the specimen rather than passed through the specimen?

Accepted Answer

dark field

Answer

bright field

Answer

phase contrast

Answer

confocal scanning laser

Answer

interference (Nomarski)

Question 2

What type of microscope would you use to examine a biofilm that was 2 mm thick?

Accepted Answer

confocal scanning laser

Answer

phase contrast

Answer

interference (Nomarski)

Answer

transmission electron

Answer

atomic force

Question 3

What type of microscope measures electric current passing through a probe rather than using any part of the electromagnetic spectrum?

Accepted Answer

atomic force

Answer

interference (Nomarski)

Answer

scanning electron

Answer

electron tomography

Answer

bright field

Question 4

What is the main difference between a negative stain and a positive stain?

Accepted Answer

A negative stain is not charged, and stains the background rather then the cell.

Answer

A negative stain has a negative charge; a positive stain is positively charged.

Answer

A negative stain is used for Gram negative cells, a positive stain for Gram positive.

Answer

A negative stain stains negative charges; a positive stain stains positive charges.

Answer

A negative stain stains the inside of cells; a positive stain stains the outside.

Question 5

Which type of microscope uses special prisms to make a thin specimen appear pseudo-3-dimensional?

Accepted Answer

Differential Interference Contrast

Answer

Phase Contrast

Answer

Dark Field

Answer

Scanning Electron Microscope

Answer

Atomic Force Microscope

Question 6

What is the main advantage of using an electron beam rather than light to illuminate a specimen?

Accepted Answer

Electrons have a shorter wavelength than light

Answer

The electron beam is brighter

Answer

The electron beam penetrates thick specimens better

Answer

It is easier to focus an electron beam

Answer

An electron beam can be used to view live, unstained cells

Question 7

What is the best technique to use if you wish to count the relative numbers of two different bacterial species on the same slide?

Accepted Answer

Fluorescence Microscope, with fluorescent antibody stain

Answer

Bright Field, with a negative stain

Answer

Phase Contrast microscope, with a Gram stain

Answer

Atomic Force Microscope, unstained

Answer

Confocal Scanning Laser Microscope, with a simple stain

Question 8

Which type of microscopy would be most suitable for examining the 3-dimensional appearance of magnetosomes inside a bacterial cell?

Accepted Answer

Cryo Electron Tomography

Answer

Differential Interference Contrast

Answer

Phase Contrast

Answer

Transmission Electron Microscopy

Answer

Confocal Scanning Laser Microscopy

Question 9

Why can't live bacteria be seen well with a bright field microscope?

Accepted Answer

The contrast achieved by bright field microscopy is too low.

Answer

They are too small.

Answer

The resolution of a bright field microscope is too poor.

Answer

The high energy light of the bright field microscope kills them.

Answer

Bright field microscopes "see" 3-dimensions, but bacteria have only two.

Question 10

Which of the following microscopes depends on interference of illuminating waves that pass through internal cellular structures that have a different refractive index?

Accepted Answer

Phase Contrast Microscope

Answer

Transmission Electron Microscope

Answer

Dark field Microscope

Answer

Cryo Electron Tomograph

Answer

Fluorescence Microscope

Question 11

The important feature of a Confocal Scanning Laser Microscope is ...

Accepted Answer

a pinhole that blocks light from all but one plane of a thick specimen

Answer

a ring condenser that only allows illumination from the side of the specimen

Answer

a nanoprobe that measures electric current at the end of a cantilevered arm

Answer

a prism that polarizes light in two planes, thereby allowing 3-D images

Answer

a sensitive detector that can detect X-rays bounced from the surface of a specimen

Question 12

A negative stain is best used to view ___ structures

Accepted Answer

uncharged

Answer

positively charged

Answer

internal

Answer

Gram negative

Answer

negatively charged

Question 13

One way to enhance contrast under a microscope without enhancing resolution is to ..

Accepted Answer

use a simple stain

Answer

use microscope slide oil

Answer

use a lower wavelength of illuminating light

Answer

use an electron microscope

Answer

It is not possible to enhance contrast without also enhancing resolution.

Question 14

In order to view this specimen, a special technique must be used. Why?

Accepted Answer

This technique must be used to view individual cells.

Answer

This technique is a form of differential stain that improves contrast.

Answer

The specimen is thinner than 0.2 microns.

Answer

The light used by this technique is polarized, which improves resolution.

Answer

This technique helps to view very thick specimens.

Question 15

An atomic force "microscope" is different enough that some people don't consider it a microscope at all. What is so different about it, compared to other microscope types?

Accepted Answer

There is no true magnification system; just a sensitive electrical probe and amplifier.

Answer

It does not use light.

Answer

It has complicated electronic components to control the focus.

Answer

It produces an image that must be stacked together with other images in a computer.

Answer

It uses a rotating illuminating beam to image the sample at multiple angles.

Question 16

How can the contrast of a microscopic image be improved?

Accepted Answer

By staining the specimen

Answer

By using a longer wavelength of illuminating light

Answer

By using electrons for illumination rather than light

Answer

By using microscope slide oil

Answer

By increasing the magnification

Question 17

Both Phase Contrast and Nomarski (DIC) microscopy are based on what optical principle?

Accepted Answer

Passing through a specimen alters the spacing of the peaks in a light wave.

Answer

Light can be separated into perpendicular polarized beams.

Answer

A 3-dimensional image can be built up by combining plane images.

Answer

Light waves can add to cancel each other, resulting in a dark image.

Answer

The angle of incidence of a light wave equals the angle of reflection.

Question 18

This microscope is especially useful for viewing biofilms and other thick specimens. A movable pinhole contributes to the clarity and focus of the image.

Accepted Answer

Confocal Scanning Laser Microscope

Answer

Scanning Electron Microscope

Answer

Fluorescence Microscope

Answer

Transmission Electron Microscope

Answer

Bright-field Microscope

Question 19

Which type of microscope is best for examining unstained protozoal cells?

Accepted Answer

Differential interference contrast microscope

Answer

Bright field microscope

Answer

Fluorescence microscope

Answer

Transmission electron microscope

Answer

Atomic force microscope

Question 20

Which type of microscope is the best to use for viewing viruses attached to human host cells?

Accepted Answer

Scanning electron microscope

Answer

Atomic force microscope

Answer

Confocal scanning laser microscope

Answer

Phase contrast microscope

Answer

Dark field microscope

Question 21

Cryo electron tomography is most useful for ..

Accepted Answer

obtaining a three-dimensional view of internal cellular structures

Answer

observing motile bacteria

Answer

viewing thick specimens

Answer

observing the molecular details of a chemical compound

Answer

identifying multiple bacterial species simultaneously from a single sample

Question 22

The acid-fast stain is an example of a differential stain. What makes it "differential"?

Accepted Answer

It uses a special differential dye during the staining process.

Accepted Answer

It stains special bacterial structures called differentials that are present in some cells.

Accepted Answer

It uses two stains, along with a solvent that removes stain from some cells but not all.

Answer

It stains the background of the slide rather than the cells.

Answer

It stains positively charged molecules in the cell rather than negatively charged molecules.

Question 23

A phase contrast microscope involves the use of which of the following hardware items?

Accepted Answer

an annular diaphragm and an etched glass plate

Answer

two Wollaston prisms

Answer

a movable pinhole

Answer

a fluorescence emission filter

Answer

a detector for reflected light beams

Question 24

For many years, when we examined the structure of certain cells by transmission electron microscopy, we saw linear striations (or stripes) that may or may not correspond to round bodies seen in cross sections of these same cells (see arrows). It would be of interest to know how many of these there are, and whether they are folded and doubled back on each other within one of the layers of the cell. What tool could best be used to answer this research question?

Accepted Answer

Cryo Electron Tomography

Answer

Scanning Electron Microscopy

Answer

Dark-field Microscopy

Answer

Atomic Force Microscopy

Answer

Nomarski (DIC) Microscopy

Question 25

For what purpose would you use a negative stain?

Accepted Answer

to stain the background around uncharged structures

Answer

to stain cells whose membranes have a positive charge

Answer

to stain cells with a thick peptidoglycan layer

Answer

to stain cells with a thin peptidoglycan layer

Answer

to stain cells without a cell wall

Question 26

A positive diagnosis for a particular disease is made by examining a throat swab stained with the Acid-Fast stain. What organism is causing this disease?

Accepted Answer

Mycobacterium

Answer

A Gram positive organism like Streptococcus

Answer

An encapsulated organism like Klebsiella

Answer

Mycoplasma

Answer

an enveloped virus like Influenza

Question 27

The contrast of a specimen viewed by light microscopy can be improved by...

Accepted Answer

blocking directly transmitted light

Answer

using immersion oil

Answer

increasing the magnification

Answer

using a blue filter under the condenser

Answer

using a longer wavelength light to illuminate the specimen

Question 28

Viewing a thick specimen, such as a bacterial biofilm, would likely require which of the following?

Accepted Answer

a movable pinhole

Answer

a special condenser

Answer

a differential stain

Answer

two Wollaston prisms

Answer

a phase-shifting element

Question 29

The picture at the right shows an unusual type of bacterium that has its flagella within its periplasm. What microscopic technique was needed to observe these flagella?

Accepted Answer

Cryo Electron Tomography

Answer

Atomic Force Microscopy

Answer

Electron Chromatography

Answer

Scanning Electron Microscopy

Answer

Phase Contrast Microscopy

Question 30

The bacteria that cause whooping cough are very tiny (about 0.3 micrometers long). You're trying to examine a specimen from a patient to see if these bacteria might be present, but you're having trouble seeing them. What could you do to get a better view?

Accepted Answer

Use a dark-field plate over the condenser to block direct illumination.

Answer

Remove the blue light filter under the stage to increase light intensity.

Answer

Reduce the magnification to improve the contrast.

Answer

Use a phase contrast microscope to improve resolution.

Answer

These bacteria cannot be seen with a light microscope.

Question 31

How can you improve the resolution of a light microscope?

Accepted Answer

Have the light pass through a medium with a refractive index <1

Answer

Use a blue filter under the condenser.

Answer

View the specimen with a negative stain.

Answer

Dim the intensity of the light source.

Answer

Use a microscope with enhanced contrast.

Question 32

Which of the following microscopes depends on the phenomenon of photon drag to differentiate between structures with different refractive index?

Accepted Answer

Phase contrast

Answer

Dark-field

Answer

Confocal

Answer

TEM

Answer

Bright-field

Question 33

What type of picture is the one that is being used to examine the very tiny organism at the right (note the scale bar)?

Accepted Answer

Transmission Electron micrograph

Answer

DIC (Nomarski) micrograph

Answer

Atomic Force micrograph

Answer

Electron cryotomogram

Answer

Confocal micrograph

Question 34

Which staining technique is correctly matched with a microscope technique for which that stain
would typically be used?

Accepted Answer

Acid Fast stain and Bright-field microscopy

Answer

Negative stain and Dark-field microscopy

Answer

Fluorescent stain and Phase Contrast microscopy

Answer

Gram stain and Differential Interference Contrast microscopy

Answer

Methylene Blue simple stain and Transmission Electron microscopy

Question 35

In this picture you are looking at ______ under a ______ microscope, stained with ______.

Accepted Answer

endospores, phase contrast, nothing

Answer

rod-shaped bacteria, dark-field, the Gram stain

Answer

endospores, transmission electron, nothing

Answer

capsules, bright-field, negative stain

Answer

protozoa, DIC (Nomarski), simple stain

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