Microbiology Principles And Explorations 9th Edition by Jacquelyn G. Black -Test Bank
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Sample Test
Chapter 3: Microscopy and Staining
Question Type: Multiple Choice
1) Which of the following statements about Leeuwenhoek’s
microscopes is false?
1. a)
Leeuwenhoek kept his technique secret.
2. b)
They magnified objects 100 to 300 times.
3. c)
For each specimen a new microscope had to be made.
4. d)
They were able to reveal very fine details of bacteria.
Answer: d
Difficulty: Medium
Learning Objective 1: LO 3.1 Review the known properties of
light, such as wavelength and resolution, and how light travels through various
media.
Section Reference 1: Section 3.1 Historical Microscopy
2)Which of the following statements about resolution is true?
1. a)
Resolution refers to the ability of a lens to distinguish adjacent objects.
2. b)
With regard to light, resolution means the same thing as wavelength.
3. c)
Resolution refers to a microscope’s ability to magnify objects.
4. d) Resolution
is equal to the distance between two adjacent crests of a wave.
Answer: a
Difficulty: Hard
Learning Objective 1: LO 3.1 Review the known properties of
light, such as wavelength and resolution, and how light travels through various
media.
Section Reference 1: Section 3.2 Principles of Microscopy
3) A compound light microscope can generally see objects as no
smaller than a _____.
1. a)
ribosome
2. b)
large protozoa
3. c)
small bacterium
d)typical virus
Answer: c
Difficulty: Easy
Learning Objective 1: LO 3.2 Identify the components and
purposes of the compound light microscope and electron microscope, providing
examples of applications of these types of microscopy.
Section Reference 1: Section 3.3 Light Microscopy
4) Light of ________ wavelength typically will result in
________ resolution.
1. a)
longer, better
2. b)
shorter, better
3. c)
any, poor
4. d)
shorter, worse
Answer: b
Difficulty: Medium
Learning Objective 1: LO 3.1 Review the known properties of
light, such as wavelength and resolution, and how light travels through various
media.
Section Reference 1: Section 3.2 Principles of Microscopy
5) The formula for the resolving power (resolution distance) of
a lens is l/2NA
(wavelength /2 x numerical aperture). What does this say about resolving
power?
1. a)
The smaller the wavelength, the greater the resolving power of the lens.
2. b)
Resolving power is not related to the lens’ numerical aperture.
3. c) We
cannot precisely calculate a lens’ resolving power.
4. d) A
larger resolving power is indicative of a better lens.
Answer: a
Difficulty: Medium
Learning Objective 1: LO 3.1 Review the known properties of
light, such as wavelength and resolution, and how light travels through various
media.
Section Reference 1: Section 3.2 Principles of Microscopy
6) When light passes through an object, ________ of the light
has occurred.
1. a)
reflection
2. b)
absorption
3. c)
transmission
4. d)
fluorescence
Answer: c
Difficulty: Easy
Learning Objective 1: LO 3.1 Review the known properties of
light, such as wavelength and resolution, and how light travels through various
media.
Section Reference 1: Section 3.2 Principles of Microscopy
7) When light bends as it passes through an object, ________ of
the light has occurred.
1. a) reflection
2. b)
absorption
3. c)
transmission
4. d)
refraction
Answer: d
Difficulty: Easy
Learning Objective 1: LO 3.1 Review the known properties of
light, such as wavelength and resolution, and how light travels through various
media.
Section Reference 1: Section 3.2 Principles of Microscopy
8) When light rays pass into an object but do not emerge,
________ has taken place.
1. a)
reflection
2. b)
absorption
3. c)
refraction
4. d)
transmission
Answer: b
Difficulty: Easy
Learning Objective 1: LO 3.1 Review the known properties of
light, such as wavelength and resolution, and how light travels through various
media.
Section Reference 1: Section 3.2 Principles of Microscopy
9) In order to make use of light for a microscopic examination
of an object the object must ________ or ________ light.
1. a)
absorb, luminesce
2. b)
transmit, absorb
3. c)
transmit, reflect
4. d)
reflect, absorb
Answer: c
Difficulty: Medium
Learning Objective 1: LO 3.1 Review the known properties of
light, such as wavelength and resolution, and how light travels through various
media.
Section Reference 1: Section 3.2 Principles of Microscopy
10) Electron microscopes have a much better resolving power when
compared to light microscopes because electrons _____.
1. a)
are invisible to the eye
2. b) have
longer wavelengths than visible light rays
3. c)
have shorter wavelengths than visible light rays
4. d)
are negatively charged
Answer: c
Difficulty: Easy
Learning Objective 1: LO 3.2 Identify the components and
purposes of the compound light microscope and electron microscope, providing
examples of applications of these types of microscopy.
Section Reference 1: Section 3.4 Electron Microscopy
11) Diffraction occurs when light _____.
1. a) is
reflected by an object
2. b)
passes through a small opening
3. c) changes
wavelengths
4. d) is
absorbed by a normally transparent object (like a glass slide)
Answer: b
Difficulty: Medium
Learning Objective 1: LO 3.1 Review the known properties of
light, such as wavelength and resolution, and how light travels through various
media.
Section Reference 1: Section 3.2 Principles of Microscopy
12) Why is diffraction a problem for microscopy?
1. a)
The lens acts as a large aperture through which light must pass.
2. b)
The small size of higher-power lenses causes severe diffraction.
3. c)
The loss of light results in blurred images.
4. d)
Diffraction of light is useful when using an oil immersion lens to view
objects.
Answer: b
Difficulty: Medium
Learning Objective 1: LO 3.1 Review the known properties of
light, such as wavelength and resolution, and how light travels through various
media.
Section Reference 1: Section 3.2 Principles of Microscopy
13) What is true about the index of refraction?
1. a) If
light rays are taken up by the object than it has a high index of refraction.
2. b)
Refraction measures the frequency of the light as it reflects from a material.
3. c)
Oil immersion lenses increase the problem of refraction.
4. d)
Light will bend as it passes through two substances with different indices of
refraction.
Answer: d
Difficulty: Hard
Learning Objective 1: LO 3.1 Review the known properties of
light, such as wavelength and resolution, and how light travels through various
media.
Section Reference 1: Section 3.2 Principles of Microscopy
14) During microscopic observation of a specimen, the amount of
light that is allowed to pass through the specimen is controlled by the:
1. a)
condenser
2. b)
objective lens
3. c)
iris diaphragm
4. d)
ocular lens
Answer: c
Difficulty: Medium
Learning Objective 1: LO 3.2 Identify the components and
purposes of the compound light microscope and electron microscope, providing
examples of applications of these types of microscopy.
Section Reference 1: Section 3.3 Light Microscopy
15) The lens closest to the slide during a microscopic
examination is the _____.
1. a)
ocular
2. b)
objective
3. c)
condenser
4. d)
compound
Answer: b
Difficulty: Easy
Learning Objective 1: LO 3.2 Identify the components and
purposes of the compound light microscope and electron microscope, providing examples
of applications of these types of microscopy.
Section Reference 1: Section 3.3 Light Microscopy
16) A compound microscope has _____.
1. a)
two eyepieces
2. b) a
total magnification of 5,000X
3. c)
only fine adjustment and no coarse adjustment
4. d) more
than one lens
Answer: d
Difficulty: Easy
Learning Objective 1: LO 3.2 Identify the components and
purposes of the compound light microscope and electron microscope, providing
examples of applications of these types of microscopy.
Section Reference 1: Section 3.3 Light Microscopy
17) The lens closest to your eyes during a microscopic
examination is the _____.
1. a)
ocular
2. b)
objective
3. c)
condenser
4. d)
compound
Answer: a
Difficulty: Easy
Learning Objective 1: LO 3.2 Identify the components and
purposes of the compound light microscope and electron microscope, providing
examples of applications of these types of microscopy.
Section Reference 1: Section 3.3 Light Microscopy
18) Most light microscopes contain a/an ________ that converges
the light beam so that it passes through the specimen.
1. a)
objective lens
2. b)
iris diaphragm
3. c)
mechanical stage
4. d)
condenser
Answer: d
Difficulty: Medium
Learning Objective 1: LO 3.2 Identify the components and
purposes of the compound light microscope and electron microscope, providing
examples of applications of these types of microscopy.
Section Reference 1: Section 3.3 Light Microscopy
19) The total magnification of a specimen being viewed with a
10X ocular lens and a 40X objective lens is _____.
1. a) 4X
2. b)
40X
3. c)
400X
4. d)
4000X
Answer: c
Difficulty: Easy
Learning Objective 1: LO 3.2 Identify the components and
purposes of the compound light microscope and electron microscope, providing
examples of applications of these types of microscopy.
Section Reference 1: Section 3.3 Light Microscopy
20) To calculate the total magnification of a light microscope
you must know the magnification of the _____ lenses.
1. a)
objective and condenser
2. b)
ocular and condenser
3. c)
objective and condenser
4. d)
objective and ocular
Answer: d
Difficulty: Medium
Learning Objective 1: LO 3.2 Identify the components and
purposes of the compound light microscope and electron microscope, providing
examples of applications of these types of microscopy.
Section Reference 1: Section 3.3 Light Microscopy
21) A parfocal microscope:
1. a)
has more than one source of illumination
2. b)
has both coarse and fine focusing adjustment
3. c)
accentuates small differences in the refractive index of intracellular
structures
4. d)
allows for specimens to remain in focus when changing between magnification
Answer: d
Difficulty: Medium
Learning Objective 1: LO 3.2 Identify the components and
purposes of the compound light microscope and electron microscope, providing
examples of applications of these types of microscopy.
Section Reference 1: Section 3.3 Light Microscopy
22) A microscope in which light rays pass directly through a
specimen is a ________ microscope.
1. a)
bright field
2. b)
dark field
3. c) phase-contrast
4. d)
Nomarski
Answer: a
Difficulty: Medium
Learning Objective 1: LO 3.2 Identify the components and
purposes of the compound light microscope and electron microscope, providing
examples of applications of these types of microscopy.
Section Reference 1: Section 3.3 Light Microscopy
23) A microscope that converts changes in the speed of light as
it passes through an object into differences in brightness is a ________
microscope.
1. a)
bright field
2. b)
dark field
3. c)
phase-contrast
4. d)
Nomarski
Answer: c
Difficulty: Medium
Learning Objective 1: LO 3.2 Identify the components and
purposes of the compound light microscope and electron microscope, providing
examples of applications of these types of microscopy.
Section Reference 1: Section 3.3 Light Microscopy
24) Ultraviolet light is a key component of:
1. a)
bright-field microscopy
2. b)
dark-field microscopy
3. c)
phase-contrast microscopy
4. d)
fluorescence microscopy
Answer: d
Difficulty: Easy
Learning Objective 1: LO 3.2 Identify the components and
purposes of the compound light microscope and electron microscope, providing
examples of applications of these types of microscopy.
Section Reference 1: Section 3.3 Light Microscopy
25) Which is a false statement about light microscopy?
1. a) A
dark-field microscope produces bright images against a dark background.
2. b) A
phase contrast microscope gives 3-dimensional images.
3. c)
Fluorescent antibody staining cannot determine whether a foreign organism such
as a microbe is present in a specimen.
4. d) A
Nomarski microscope produces much higher resolution than the standard
phase-contrast microscope.
Answer: c
Difficulty: Medium
Learning Objective 1: LO 3.2 Identify the components and
purposes of the compound light microscope and electron microscope, providing
examples of applications of these types of microscopy.
Section Reference 1: Section 3.3 Light Microscopy
26) The advent of the electron microscope allowed ________ to be
viewed for the first time.
1. a)
protozoa
2. b)
bacteria
3. c)
viruses
4. d)
algae
Answer: c
Difficulty: Easy
Learning Objective 1: LO 3.2 Identify the components and
purposes of the compound light microscope and electron microscope, providing
examples of applications of these types of microscopy.
Section Reference 1: Section 3.4 Electron Microscopy
27) Electron microscopes use ________ to focus the electron
beam.
1. a)
glass lenses
2. b)
electromagnets
3. c)
mechanical stages
4. d)
laser beams
Answer: b
Difficulty: Medium
Learning Objective 1: LO 3.2 Identify the components and
purposes of the compound light microscope and electron microscope, providing
examples of applications of these types of microscopy.
Section Reference 1: Section 3.4 Electron Microscopy
28) The best electron microscopes have a resolution of _____ nm.
1. a)
0.1
2. b) 1
3. c) 10
4. d)
100
Answer: b
Difficulty: Hard
Learning Objective 1: LO 3.2 Identify the components and
purposes of the compound light microscope and electron microscope, providing
examples of applications of these types of microscopy.
Section Reference 1: Section 3.4 Electron Microscopy
29) Transmission electron microscopes have a maximum
magnification of _____.
1. a)
1,000X
2. b)
100,000X
3. c)
500,000X
4. d)
1,000,000X
Answer: c
Difficulty: Medium
Learning Objective 1: LO 3.2 Identify the components and
purposes of the compound light microscope and electron microscope, providing
examples of applications of these types of microscopy.
Section Reference 1: Section 3.4 Electron Microscopy
30) Electron microscopes:
1. a)
that are scanning have better resolution than those that are transmission
2. b)
are much more expensive and take up more space than light microscopes
3. c)
can use the same preparations of specimens that have been prepared for viewing
with a light microscope
4. d)
have a resolving power approximately 10 times better than the best light
microscope
Answer: b
Difficulty: Easy
Learning Objective 1: LO 3.2 Identify the components and
purposes of the compound light microscope and electron microscope, providing
examples of applications of these types of microscopy.
Section Reference 1: Section 3.4 Electron Microscopy
31) Three dimensional views of cells and other small objects
could best be obtained using a:
1. a)
phase contrast microscope
2. b)
dark-field microscope
3. c)
transmission electron microscope (TEM)
4. d)
scanning electron microscope (SEM)
Answer: d
Difficulty: Hard
Learning Objective 1: LO 3.2 Identify the components and
purposes of the compound light microscope and electron microscope, providing examples
of applications of these types of microscopy.
Section Reference 1: Section 3.4 Electron Microscopy
32) Which of the following can be used to examine live
specimens?
1. a)
TEM
2. b)
SEM
3. c)
scanning tunneling electron microscope
4. d)
atomic force microscope
Answer: c
Difficulty: Medium
Learning Objective 1: LO 3.2 Identify the components and
purposes of the compound light microscope and electron microscope, providing
examples of applications of these types of microscopy.
Section Reference 1: Section 3.4 Electron Microscopy
33) The technique that involves the evaporation of water from a
frozen and fractured specimen is called:
1. a)
shadow casting
2. b)
freeze-etching
3. c)
heat fixation
4. d)
freeze-fracturing
Answer: b
Difficulty: Hard
Learning Objective 1: LO 3.2 Identify the components and
purposes of the compound light microscope and electron microscope, providing
examples of applications of these types of microscopy.
Section Reference 1: Section 3.4 Electron Microscopy
34) Colored photos of electron micrographs:
1. a)
reflect the color of the specimen before it was frozen
2. b)
are false color added on during image preparation
3. c)
reflect the color of the specimen after it was frozen
4. d)
are always in pastel shades
Answer: b
Difficulty: Medium
Learning Objective 1: LO 3.2 Identify the components and
purposes of the compound light microscope and electron microscope, providing
examples of applications of these types of microscopy.
Section Reference 1: Section 3.4 Electron Microscopy
35) Atomic force microscope:
1. a)
allows 3 dimensional imaging and measurement of structures as small as
nucleotides in DNA
2. b) is
not yet capable of measuring small forces
3. c)
involves ultraviolet light exciting molecules so that they release light of a
longer wavelength
4. d)
has a special condenser and objective lens
Answer: a
Difficulty: Medium
Learning Objective 1: LO 3.2 Identify the components and
purposes of the compound light microscope and electron microscope, providing
examples of applications of these types of microscopy.
Section Reference 1: Section 3.4 Electron Microscopy
36) The term “basic dyes” refers to the fact that these dyes are
_____.
1. a)
easily prepared
2. b)
positively charged
3. c)
attracted to positively charged cell structures
4. d)
simple in their composition
Answer: b
Difficulty: Medium
Learning Objective 1: LO 3.3 Discuss the techniques and purpose
of staining specimens and why differential stains such as the Gram stain,
capsule stain, endospore stain, and flagellar stain are used.
Section Reference 1: Section 3.5 Techniques of Light Microscopy
37) Which of the following statements about preparing a light
microscope specimen is false?
1. a)
Organisms must be heat fixed before being viewed in a hanging drop slide.
2. b)
Smears are loopfuls of medium spread on the surface of a glass slide.
3. c)
Wet mount preparations give good views of microbial mobility.
4. d)
The depth of a smear affects the results;if too thin you may find no organisms.
Answer: a
Difficulty: Easy
Learning Objective 1: LO 3.3 Discuss the techniques and purpose
of staining specimens and why differential stains such as the Gram stain,
capsule stain, endospore stain, and flagellar stain are used.
Section Reference 1: Section 3.5 Techniques of Light Microscopy
38) A simple stain:
1. a)
uses only a single dye.
2. b)
requires only one step to stain a slide.
3. c)
distinguishes between two different parts of an organism.
4. d) is
composed of an equal balance of acidic and basic dyes.
Answer: a
Difficulty: Easy
Learning Objective 1: LO 3.3 Discuss the techniques and purpose
of staining specimens and why differential stains such as the Gram stain,
capsule stain, endospore stain, and flagellar stain are used.
Section Reference 1: Section 3.5 Techniques of Light Microscopy
39) Which of the following is not a differential stain?
1. a)
Gram stain
2. b)
Schaeffer-Fulton
3. c)
acid-fast stain
4. d)
flagellar stain
Answer: d
Difficulty: Medium
Learning Objective 1: LO 3.3 Discuss the techniques and purpose
of staining specimens and why differential stains such as the Gram stain,
capsule stain, endospore stain, and flagellar stain are used.
Section Reference 1: Section 3.5 Techniques of Light Microscopy
40) In a Gram stain, the mordant is _____.
1. a)
crystal violet
2. b)
iodine
3. c)
water
4. d)
alcohol
Answer: b
Difficulty: Medium
Learning Objective 1: LO 3.3 Discuss the techniques and purpose
of staining specimens and why differential stains such as the Gram stain,
capsule stain, endospore stain, and flagellar stain are used.
Section Reference 1: Section 3.5 Techniques of Light Microscopy
41) In a properly executed Gram stain, Gram positive organisms
appear ________ while Gram negative organisms appear ________.
1. a)
pink, clear
2. b)
pink, purple
3. c) purple,
pink
4. d)
purple, blue
Answer: c
Difficulty: Easy
Learning Objective 1: LO 3.3 Discuss the techniques and purpose
of staining specimens and why differential stains such as the Gram stain,
capsule stain, endospore stain, and flagellar stain are used.
Section Reference 1: Section 3.5 Techniques of Light Microscopy
42) Why do basic dyes attach to most bacterial surfaces?
1. a)
Most bacterial surfaces are negatively charged.
2. b)
Bacterial cells take up safranin.
3. c)
Most bacterial surfaces resist taking up the stain.
4. d)
Most bacterial surfaces do not have a charge.
Answer: a
Difficulty: Medium
Learning Objective 1: LO 3.3 Discuss the techniques and purpose
of staining specimens and why differential stains such as the Gram stain,
capsule stain, endospore stain, and flagellar stain are used.
Section Reference 1: Section 3.5 Techniques of Light Microscopy
43) If the step involving iodine were left out of a Gram stain,
which of the following would best describe the results?
1. a)
Gram negative cells would look Gram positive.
2. b)
Gram positive cells would look Gram negative.
3. c)
All rods would be pink, all cocci purple.
4. d)
All cells would be purple.
Answer: b
Difficulty: Medium
Learning Objective 1: LO 3.3 Discuss the techniques and purpose
of staining specimens and why differential stains such as the Gram stain,
capsule stain, endospore stain, and flagellar stain are used.
Section Reference 1: Section 3.5 Techniques of Light Microscopy
44) Which stain would be the best choice for detecting mycobacterium
(the bacteria responsible for tuberculosis and leprosy)?
1. a)
simple stain
2. b)
endospore stain
3. c)
acid-fast stain
4. d)
Gram stain
Answer: c
Difficulty: Easy
Learning Objective 1: LO 3.3 Discuss the techniques and purpose
of staining specimens and why differential stains such as the Gram stain,
capsule stain, endospore stain, and flagellar stain are used.
Section Reference 1: Section 3.5 Techniques of Light Microscopy
45) Suitable stains for use in the Ziehl-Neelsen acid-fast stain
are _____.
1. a)
crystal violet and eosin
2. b)
carbolfuschin and methylene blue
3. c)
carbolfuschin and safranin
4. d)
safranin and methylene blue
Answer: b
Difficulty: Hard
Learning Objective 1: LO 3.3 Discuss the techniques and purpose
of staining specimens and why differential stains such as the Gram stain,
capsule stain, endospore stain, and flagellar stain are used.
Section Reference 1: Section 3.5 Techniques of Light Microscopy
46) Which type of staining results in a clear object being
viewed against a dark background?
1. a)
Simple stain
2. b)
Negative stain
3. c)
Endospore stain
4. d)
Flagellar stain
Answer: b
Difficulty: Medium
Learning Objective 1: LO 3.3 Discuss the techniques and purpose
of staining specimens and why differential stains such as the Gram stain,
capsule stain, endospore stain, and flagellar stain are used.
Section Reference 1: Section 3.5 Techniques of Light Microscopy
47) The counterstain in theendospore stain is _____.
1. a)
malachite green
2. b)
crystal violet
3. c)
safranin
4. d)
methylene blue
Answer: c
Difficulty: Medium
Learning Objective 1: LO 3.3 Discuss the techniques and purpose
of staining specimens and why differential stains such as the Gram stain,
capsule stain, endospore stain, and flagellar stain are used.
Section Reference 1: Section 3.5 Techniques of Light Microscopy
48) Bacterial capsules can best be visualized by _______
staining.
1. a)
flagellar
2. b)
crystal violet
3. c)
negative
4. d)
mordant
Answer: c
Difficulty: Medium
Learning Objective 1: LO 3.3 Discuss the techniques and purpose
of staining specimens and why differential stains such as the Gram stain,
capsule stain, endospore stain, and flagellar stain are used.
Section Reference 1: Section 3.5 Techniques of Light Microscopy
49) What statement about microscopy and staining techniques is
false?
1. a)
Many species look identical under the microscope.
2. b)
Staining and microscopic examination are usually all that is need to identify a
microorganism.
3. c)
Microscopes are of little use unless the specimens are prepared properly.
4. d)
The degree of contrast is equally important as resolution and magnification.
Answer: b
Difficulty: Medium
Learning Objective 1: LO 3.3 Discuss the techniques and purpose
of staining specimens and why differential stains such as the Gram stain,
capsule stain, endospore stain, and flagellar stain are used.
Section Reference 1: Section 3.5 Techniques of Light Microscopy
50) When given a microorganism to identify, which of the
following would be useful?
1. a) A
Gram stain
2. b) A
transmission electron micrograph
3. c)
Biochemical and genetic characteristics
4. d)
All of the above
Answer: d
Difficulty: Easy
Learning Objective 1: LO 3.3 Discuss the techniques and purpose
of staining specimens and why differential stains such as the Gram stain,
capsule stain, endospore stain, and flagellar stain are used.
Section Reference 1: Section 3.5 Techniques of Light Microscopy
51) Which of the following stains has been used on this
microorganism?
1. a)
Flagellar stain
2. b)
Capsule stain
3. c)
Endospore stain
4. d) No
stain
Answer: c
Difficulty: Easy
Learning Objective 1: LO 3.3 Discuss the techniques and purpose
of staining specimens and why differential stains such as the Gram stain,
capsule stain, endospore stain, and flagellar stain are used.
Section Reference 1: Section 3.5 Techniques of Light Microscopy
52) The image of this fungus was taken using a:
1. a)
confocal microscope
2. b)
atomic force microscope
3. c)
compound light microscope
4. d)
fluorescence microscope
Answer: b
Difficulty: Medium
Learning Objective 1: LO 3.2 Identify the components and
purposes of the compound light microscope and electron microscope, providing
examples of applications of these types of microscopy.
Section Reference 1: Section 3.4 Electron Microscopy
53) This structure converges the light beams so they pass
through the specimen.
1. a) A
2. b) B
3. c) C
4. d) D
Answer: c
Difficulty: Easy
Learning Objective 1: LO 3.2 Identify the components and
purposes of the compound light microscope and electron microscope, providing
examples of applications of these types of microscopy.
Section Reference 1: Section 3.3 Light Microscopy
Question Type: Essay
54) 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?
Answer: Light of a shorter wavelength would give you better
resolution when using a microscope because shorter wavelengths can pass more
easily between the separate structures and therefore define them more clearly
and produce a sharper image. There is no direct relationship between the
total magnification and the resolution, rather an indirect relationship in that
the resolving power is related to the numerical aperture. The numerical
aperture of the lens differs in accordance with the power of magnification and
intrinsic properties of the lens. Although it is possible to have lenses
of different powers of magnification with the same numerical aperture, it is
more likely that the larger the magnification the larger the numerical aperture
and therefore the lower the resolving power of the lens. It is more
likely that the 500X lens will give you less resolution than the 100X lens.
Difficulty: Hard
Learning Objective 1: LO 3.1 Review the known properties of
light, such as wavelength and resolution, and how light travels through various
media.
Section Reference 1: Section 3.2 Principles of Microscopy
55) What is the Gram stain? What does it distinguish?
Answer: Gram staining is based on the ability of the bacterial
cell wall to take up and retain a crystal violet/iodine dye complex. Bacteria
cell walls are stained by the crystal violet. Iodine is subsequently added as a
mordant to form the crystal violet-iodine complex so that the dye cannot be
removed easily. A decolorizer is then added to dissolve the lipid layer from
the gram-negative cells which allows the complex to wash out of this type of cell
wall. Gram stain distinguishes between gram-positive cells (purple),
gram-negative cells (red from the saffranin counterstain) and cells which are
nonreactive or gram-variable.
Difficulty: Medium
Learning Objective 1: LO 3.3 Discuss the techniques and purpose
of staining specimens and why differential stains such as the Gram stain,
capsule stain, endospore stain, and flagellar stain are used.
Section Reference 1: Section 3.5 Techniques of Light Microscopy
56) 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).
Answer: Light microscopy uses visible wavelengths of light,
while electron microscopes use beams of electrons instead of light. Light
microscopy directs the light with glass lenses, while electron microscopy
directs the electron beam with electromagnetic lense. Electrons, which
have a smaller wavelength than visible light, allow a much higher
resolution. Electron microscopy requires that the beam pass through a
vacuum as air molecules would otherwise scatter the beam and therefore are much
more expensive than light microscopes. They also take up more room and
are not as portable. The magnification of a light microscope is up to
1000X, while an electron microscope allows for many time that magnification
(e.g., 500,000X). In other words with a light microscope one can
see individual cells and bacteria (e.g., 1um to 10nm range), while with an
electron microscope one can see all that plus viruses, organelles (e.g.,
ribosomes) and even individual proteins (e.g., 1nm to 10nm range).
Difficulty: Medium
Learning Objective 1: LO 3.2 Identify the components and
purposes of the compound light microscope and electron microscope, providing
examples of applications of these types of microscopy.
Section Reference 1: Section 3.3 Light Microscopy
Section Reference 2: Section 3.4 Electron Microscopy
Chapter 4:Characteristics of Prokaryotic and Eukaryotic Cells
Question Type: Multiple Choice
1) Which of the following groups of organisms is not
prokaryotic?
1. a)
Archaea
2. b)
Bacteria
3. c)
Eubacteria
4. d)
Eukarya
Answer: d
Difficulty: Easy
Learning Objective 1: LO 4.1 Compare and contrast prokaryotic
and eukaryotic cell types, describing typical sizes, shapes, and arrangements
of bacterial cells.
Section Reference 1: Section 4.2 Prokaryotic Cells
2) Which of the following is not a common bacterial shape?
1. a)
Spirochete
2. b)
Coccus
3. c)
Disc
4. d)
Bacillus
Answer: c
Difficulty: Easy
Learning Objective 1: LO 4.1 Compare and contrast prokaryotic
and eukaryotic cell types, describing typical sizes, shapes, and arrangements
of bacterial cells.
Section Reference 1: Section 4.2 Prokaryotic Cells
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