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Chapter 2 Study Guide

Terms in this set (80)

B
Which term is used to refer to a wave's rate of vibration?
A. amplitude
B. frequency
C. trough
D. wavelength
D
On the figure, which letter represents a refracted ray of light?
A. A
B. B
C. C
D. D
A
On the electromagnetic spectrum, which type of wave has the shortest wavelength?
A. cosmic ray
B. infrared ray
C. ultraviolet ray
D. visible light
A
Dyes are often used during microscopy to increase which of the following?
A. contrast
B. magnification
C. motility
D. resolution
A
Which of the following was the first to use the term "cells"?
A. Robert Hooke
B. Robert Koch
C. Carolus Linnaeus
D. Antonie van Leeuwenhoek
D
Which of the following is the typical magnification of an object viewed using a 10× ocular lens and a 100× objective lens on a brightfield microscope?
A. 1×
B. 10×
C. 100×
D. 1000×
A
Most modern microscopes have two eyepieces, meaning that they are which of the following?
A. binocular
B. monocular
C. oil immersion
D. trinocular
D
An annular stop is used for which type of microscopy?
A. confocal
B. darkfield
C. fluorescence
D. phase contrast
D
Which of the following is the specific name for a stain that colors the background but not the specimen?
A. acid-fast stain
B. counterstain
C. differential stain
D. negative stain
D
Which type of microscopy would work best for viewing internal cell structures?
A. atomic force microscopy
B. scanning electron microscopy
C. scanning tunneling microscopy
D. transmission electron microscopy
B
The Gram-staining procedure is best described as which of the following?
A. complex staining
B. differential staining
C. negative staining
D. simple staining
B
When there is a substantial difference in refractive index between two materials, which of the following describes what will happen to light passing from one material to the other?
A. It will fail to be refracted.
B. It will undergo a large amount of refraction.
C. It will undergo a small amount of refraction.
D. It will undergo a variable amount of refraction.
D
In microscopy, the focal length refers to which of the following?
A. a description of the wavelength needed for an image to be in focus
B. a measure of the amount of refraction produced by a lens
C. a measure of the thickness of the lens needed for an image to be in focus
D. the distance to the image point (at which all light entering a lens is parallel)
B
Which of the following are pigments used in microscopy to absorb and reflect light?
A. chromatographs
B. chromophores
C. oilophores
D. photophores
A
Negative staining is the standard approach used to visualize which structure(s)?
A. capsules
B. endospores
C. flagella
D. nucleoid regions
D
Which is a standard mordant used in flagella staining?
A. basic fuchsin
B. iodine
C. safranin
D. tannic acid
C
17. Which of the following pairs are common acid-fast staining techniques?
A. Gram and Kinyoun
B. negative and Schaeffer-Fulton
C. Ziehl-Neelsen and Kinyoun
D. Ziehl-Neelsen and Schaeffer-Fulton
B
Which is the primary stain used in the Ziehl-Neelsen technique?
A. acid-alcohol
B. carbolfuchsin
C. crystal violet
D. methylene blue
B
Which is the correct order of steps in Gram staining?
A. crystal violet stain, ethanol decolorization, Gram's iodine mordant, safranin counterstain
B. crystal violet stain, Gram's iodine mordant, ethanol decolorization, safranin counterstain
C. ethanol stain, crystal violet rinse, safranin counterstain, Gram's iodine mordant
D. safranin stain, Gram's iodine mordant, ethanol decolorization, crystal violet counterstain
A
It is important to fix bacterial smears on a slide for which of the following reasons?
A. to attach them to the slide
B. to cause swelling of the cell to make interior structures more visible
C. to enhance the uptake of stains
D. to provide a nutrient medium to sustain the bacteria
D
Which of the following is not commonly used for chemical fixation?
A. acetic acid
B. ethanol
C. glutaraldehyde
D. iodine
D
Which of the following is not involved in preparing a bacterial slide for Gram staining?
A. allowing the sample to dry on the slide
B. fixing the specimen to the slide
C. placing a smear on the slide
D. preparing a wet mount
C
Which of the following most specifically refers to stains with positively charged chromophores?
A. acid-fast dyes
B. acidic dyes
C. basic dyes
D. positive dyes
D
Which of the following most specifically refers to a stain that dyes a specimen rather than the background?
A. counterstain
B. mordant
C. negative stain
D. positive stain
C
Which of the following describes the difference between the Ziehl-Neelsen and Kinyoun acid-fast staining techniques?
A. The Ziehl-Neelsen technique uses a counterstain and the Kinyoun technique does not.
B. The Ziehl-Neelsen technique uses an acidic dye and the Kinyoun technique does not.
C. The Ziehl-Neelsen technique uses heat and the Kinyoun technique does not.
D. The Ziehl-Neelsen technique uses two dyes and the Kinyoun technique does not.
D
Which of the following described the difference between gram-positive and gram-negative cells that causes them to stain differently after Gram staining?
A. Gram-positive cells have a mycolic acid layer in their cell walls that holds in stain, whereas gram-negative cells lack this layer.
B. Gram-positive cells have capsules and gram-negative cells have S layers.
C. Gram-positive cells have thicker cell membranes than gram-negative cells.
D. Gram-positive cells have thicker peptidoglycan layers in their cell walls than do gram-negative cells
A
27. Which of the following would not potentially cause a gram-positive cell to appear gram-negative after Gram staining?
A. counterstaining with crystal violet instead of safranin
B. exposing the cells to ethanol for too long
C. using older bacterial cultures
D. using safranin as a primary stain
D
Which of the following does not cause the probe to move up and down above the specimen in atomic force microscopy?
A. chemical bonding
B. electrostatic forces
C. van der Waals forces
D. variations in current
C
Quantum tunneling of electrons is important in the mechanism underlying which microscope type?
A. AFM
B. SEM
C. STM
D. TEM
B
Which of the following is the chemical in some bacterial cells' walls that makes them resist decolorization after acid-fast staining?
A. acetic acid
B. mycolic acid
C. peptidoglycan
D. phospholipid
C
Gram staining is useful for bacterial identification. Which of the following is another way it is most useful?
A. Knowing Gram staining results allows a researcher to know which organisms a bacterium can infect.
B. Knowing Gram staining results allows a researcher to select the appropriate growth medium for optimal bacterial growth.
C. Knowing Gram staining results is helpful in choosing an effective antibiotic.
D. Knowing Gram staining results is helpful in understanding a bacterium's metabolic requirements.
A
Which of the following is not true regarding capsule staining?
A. Capsules are typically stained using basic dyes.
B. Capsule staining does not require heat fixation in advance.
C. Capsule staining requires careful selection of a stain that can stain the capsule itself.
D. Capsule staining typically involves negative staining.
C
Because endospores are difficult to stain, which of the following is generally needed?
A. Heat must be used to make the endospore take up stain.
B. Mycolic acid must be added to encourage the endospore to take up stain.
C. Negative staining must be used to stain endospores because they do not absorb stain.
D. The cells must be cooled to make the endospore more brittle prior to staining.
A
34. When endospores are stained using the Schaeffer-Fulton method, which of the following correctly describes how they appear after staining?
A. The endospore appears green within a pink cell, because only the endospore retained the primary stain.
B. The entire cell appears green because the endospore surrounds all the vegetative material.
B. The entire cell appears pink because the endospore surrounds all the vegetative material.
C. The entire cell appears pink except for a clear area representing the endospore
C
Specimens for TEM are prepared by doing which of the following?
A. dehydrating the specimen in ethanol and then coating it in a material that will repel electrons
B. sputter coating with a substance such as gold to repel electrons
C. using an ultramicrotome to cut very thin sections from samples embedded in plastic resin
D. using chemical fixation, followed by standard staining techniques such as the Gram stain
False
T OR F: In fluorescence, emitted photons have the same amount of energy as absorbed photons.
False
T OR F: A microscope with very high magnification and low resolution would allow you to clearly see small structures.
False
T OR F: The difference between a simple microscope and a compound microscope is that the latter only has one lens.
False
T OR F: Flagella staining is very useful for diagnostic purposes in medical settings.
False
T OR F: The transmission electron microscope and scanning electron microscope produce very similar images, but the former can be show three-dimensional external structures.
True
T OR F: Differential interference contrast microscopy produces three-dimensional images of specimens
True
T OR F: During specimen preparation for transmission electron microscopy, the specimens are dehydrated in alcohol and embedded in plastic resin.
True
T OR F: In atomic force microscopy, the movement of the probe tip is determined using Hooke's law of elasticity.
Ampliude
The height of a wave peak or depth if a wave trough.
Frequency
The rate of vibration of a wave.
Visible Light
Electromagnetic radiation within certain parameters.
Wavelength
The distance between two wave peaks.
Absorbance
A material captures high energy.
Diffraction
Light bends or scatters as it interacts with objects or openings.
Interference
Two waves interact.
Refraction
Light waves change direction when they enter new medium.
Transmission
A wave travels through something.
Brightfield
Widely used and easily available; used for examining common protists, bacteria, and tissues; strains are often needed.
Darkfield
Used to examine an image produced with light that hits a specimen indirectly owing to the use of an opaque light stop; often used to view living microorganisms without stains
Fluorescence
Commonly used clinically; helpful in distinguishing living from dead cells, finding molecules within a cell, and for immunostaining
Phase Contrast
Uses an annular stop, refraction, and interference to produce relatively high-resolution images without stains
Two-Photon
Often used to penetrate thick specimens, such as biofilms, with long-wavelength light
Atomic Force Microscopy
Measures variations in the height of a probe moving over the specimen; height variations occur to maintain a constant current
Scanning Electron Microscopy
Yields images from electrons produced by an electron beam hitting the surface of a sputter-coated specimen.
Scanning Tunneling Microscopy
Measures changes in current as a probe is moved at a constant height over a specimen.
Transmission Electron Micscopy
Produces images from electrons that pass through a very thin specimen, allowing internal structures to be visualized.
Acid- Fast Staining
Carbolfuchsin, acid alcohol, and methylene blue.
Capsule Stain
India ink or nigrosin, sometimes with positive staining.
Endospore Stain
Malachite green, safranin.
Flagella Stain
Tannic acid or potassium alum, pararosaniline or basic fuchsin.
Gram Stain
Crystal violet, iodine, ethanol, safranin.
The cell will probably appear purple/violet, which will not correctly indicate its cell wall structure.
A gram-negative cell is stained, but the ethanol step is skipped.
The cell will probably appear pink, which will not correctly indicate its cell wall structure.
A gram-positive cell with a severely damaged cell wall is stained.
The cell will appear pink.
A healthy gram-negative cell is stained.
The cell will appear purple/violet.
A healthy gram-positive cell is stained.
Higher
50. Compared with air, water has a(n) ________ refractive index.
Scanning
The ________ electron microscope produces high-resolution images of three-dimensional surface structures of sputter-coated specimens.
Micrographia
Robert Hooke published ________, in which he described his observations of cork via compound microscopes.
Darkfield
________ microscopy uses an opaque stop, is useful for viewing living organisms without using stains, and produces images with a dark background.
Mycolic Acids
Acid-fast bacteria have ________ in their cell walls that retain carbolfuschin stain.
Blue
In acid-fast staining, cells that are not acid-fast usually appear ________.
Gold
During preparation of specimens for scanning electron microscopy, specimens are often sputter coated with ________ or a similar material.
Nigrosin
Negative staining of capsules is commonly done using India ink or ________.
Kinyoun
An acid-fast staining technique similar to the Ziehl-Neelsen technique is called the ________ technique.
Larger
When an object is relatively small relative to a wavelength of light, diffraction is ________ than if an object is relatively large.
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