Multiple choice - Test Bank and Solution Manual · Web viewChapter 3: Microscopy and Staining...
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Chapter 3: Microscopy and Staining Question Type: Multiple Choice 1) 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. 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? 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. Answer: a Difficulty: Hard
Transcript of Multiple choice - Test Bank and Solution Manual · Web viewChapter 3: Microscopy and Staining...
Chapter 3: Microscopy and Staining
Question Type: Multiple Choice
1) 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.
Answer: d
Difficulty: MediumLearning 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?
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.
Answer: a
Difficulty: HardLearning 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 _____.
a) ribosomeb) large protozoac) small bacteriumd) 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.
a) longer, betterb) shorter, betterc) any, poord) shorter, worse
Answer: b
Difficulty: MediumLearning 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 /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 the lens’ numerical aperture.c) We cannot precisely calculate a lens resolving power.d) A larger resolving power is indicative of a better lens.
Answer: a
Difficulty: MediumLearning 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.
a) reflectionb) absorptionc) transmissiond) fluorescence
Answer: c
Difficulty: EasyLearning 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.
a) reflectionb) absorptionc) transmissiond) refraction
Answer: d
Difficulty: EasyLearning 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.
a) reflectionb) absorptionc) refractiond) transmission
Answer: b
Difficulty: EasyLearning 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.
a) absorb, luminesceb) transmit, absorbc) transmit, reflectd) reflect, absorb
Answer: c
Difficulty: MediumLearning 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 _____.
a) are invisible to the eyeb) have longer wavelengths than visible light raysc) have shorter wavelengths than visible light raysd) are negatively charged
Answer: c
Difficulty: EasyLearning 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 _____.
a) is reflected by an objectb) passes through a small openingc) changes wavelengthsd) is absorbed by a normally transparent object (like a glass slide)
Answer: b
Difficulty: MediumLearning 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?
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.
Answer: b
Difficulty: MediumLearning 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?
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: d
Difficulty: HardLearning 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:
a) condenserb) objective lensc) iris diaphragmd) ocular lens
Answer: c
Difficulty: MediumLearning 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 _____.
a) ocularb) objectivec) condenserd) compound
Answer: b
Difficulty: EasyLearning 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 _____.
a) two eyepiecesb) a total magnification of 5,000Xc) only fine adjustment and no coarse adjustmentd) more than one lens
Answer: d
Difficulty: EasyLearning 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 _____.
a) ocularb) objectivec) condenserd) compound
Answer: a
Difficulty: EasyLearning 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.
a) objective lensb) iris diaphragm
c) mechanical staged) condenser
Answer: d
Difficulty: MediumLearning 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 _____.
a) 4Xb) 40Xc) 400Xd) 4000X
Answer: c
Difficulty: EasyLearning 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.
a) objective and condenser b) ocular and condenser c) objective and condenser d) objective and ocular
Answer: d
Difficulty: MediumLearning 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:
a) has more than one source of illuminationb) has both coarse and fine focusing adjustmentc) accentuates small differences in the refractive index of intracellular structures d) allows for specimens to remain in focus when changing between magnification
Answer: d
Difficulty: MediumLearning 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.
a) bright fieldb) dark fieldc) phase-contrastd) Nomarski
Answer: a
Difficulty: MediumLearning 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.
a) bright fieldb) dark fieldc) phase-contrastd) 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:
a) bright-field microscopyb) dark-field microscopyc) phase-contrast microscopyd) fluorescence microscopy
Answer: d
Difficulty: EasyLearning 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?
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.
Answer: c
Difficulty: MediumLearning 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.
a) protozoab) bacteriac) virusesd) algae
Answer: c
Difficulty: EasyLearning 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.
a) glass lensesb) electromagnetsc) mechanical stagesd) laser beams
Answer: b
Difficulty: MediumLearning 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.
a) 0.1 b) 1 c) 10 d) 100
Answer: b
Difficulty: HardLearning 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 _____.
a) 1,000Xb) 100,000Xc) 500,000X
d) 1,000,000X
Answer: c
Difficulty: MediumLearning 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:
a) that are scanning have better resolution than those that are transmissionb) are much more expensive and take up more space than light microscopesc) can use the same preparations of specimens that have been prepared for viewing with a light microscoped) have a resolving power approximately 10 times better than the best light microscope
Answer: b
Difficulty: EasyLearning 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 object could best be obtained using a:
a) phase contrast microscopeb) dark-field microscopec) transmission electron microscope (TEM)d) scanning electron microscope (SEM)
Answer: d
Difficulty: HardLearning 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?
a) TEMb) SEMc) scanning tunneling electron microscoped) atomic force microscope
Answer: c
Difficulty: MediumLearning 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:
a) shadow castingb) freeze-etchingc) heat fixationd) freeze-fracturing
Answer: b
Difficulty: HardLearning 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:
a) reflect the color of the specimen before it was frozenb) are false color added on during image preparationc) reflect the color of the specimen after it was frozend) are always in pastel shades
Answer: b
Difficulty: MediumLearning 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:
a) allows 3 dimensional imaging and measurement of structures as small as nucleotides in DNAb) is not yet capable of measuring small forces c) involves ultraviolet light exciting molecules so that they release light of a longer wavelengthd) has a special condenser and objective lens
Answer: a
Difficulty: MediumLearning 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 _____.
a) easily preparedb) positively chargedc) attracted to positively charged cell structuresd) simple in their composition
Answer: b
Difficulty: MediumLearning 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?
a) Organisms must be heat fixed before viewed in a hanging drop slide.b) Smears are loopfuls of medium spread on the surface of a glass slide.c) Wet mounts preparations give good views of microbial mobility.d) The depth of a smear affects the results; if too thin you may find no organisms.
Answer: a
Difficulty: EasyLearning 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:
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 acid and basic dyes.
Answer: a
Difficulty: EasyLearning 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?
a) Gram stainb) Schaeffer-Fultonc) acid-fast staind) flagellar stain
Answer: d
Difficulty: MediumLearning 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 _____.
a) crystal violetb) iodinec) waterd) 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 ________.
a) pink, clearb) pink, purplec) purple, pinkd) purple, blue
Answer: c
Difficulty: EasyLearning 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?
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.
Answer: a
Difficulty: MediumLearning 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?
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.
Answer: b
Difficulty: MediumLearning 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)?
a) simple stainb) endospore stain c) acid-fast staind) Gram stain
Answer: c
Difficulty: EasyLearning 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 _____.
a) crystal violet and eosinb) carbolfuschin and methylene bluec) carbolfuschin and safranind) safranin and methylene blue
Answer: b
Difficulty: HardLearning 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?
a) Simple stain
b) Negative stainc) Endospore stain d) Flagellar stain
Answer: b
Difficulty: MediumLearning 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 the endospore stain is _____.
a) malachite greenb) crystal violetc) safranind) methylene blue
Answer: c
Difficulty: MediumLearning 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) Bacteria capsules can best be visualized by _______ staining.
a) flagellarb) crystal violetc) negatived) mordant
Answer: c
Difficulty: MediumLearning 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?
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.
Answer: b
Difficulty: MediumLearning 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?
a) A gram stainb) A transmission electron micrographc) Biochemical and genetic characteristicsd) All of the above
Answer: d
Difficulty: EasyLearning 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?
a) Flagellar stainb) Capsule stainc) Endospore staind) No stain
Answer: c
Difficulty: EasyLearning 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:
a) confocal microscopeb) atomic force microscopec) compound light microscoped) fluorescence microscope
Answer: b
Difficulty: MediumLearning 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.
a) Ab) Bc) Cd) D
Answer: c
Difficulty: EasyLearning 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: HardLearning 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: MediumLearning 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: MediumLearning 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 MicroscopySection Reference 2: Section 3.4 Electron Microscopy
