Microbiology flash cards
Stain outcome: Acid-fast stain Acid-fast Non-acid-fast
-Bright pink (fuchsia) -Blue
Microscope: Uses immersion oil
-Compound light
Microscope: Uses light
-Compound light -Darkfield -Phase-contrast -Differential interference contrast -Fluorescence -Confocal
Microscope: Specimens are stained
-Compound light -Fluorescence -Confocal -Scanning electron -Transmission electron
Microscope: One plane at a time is imaged to reconstruct a 3-D view
-Confocal
Microscope: Specimen is light (white) on a dark background
-Darkflield -Phase-contrast
Microscope: Specimens are not stained
-Darkflield -Phase-contrast -Differential interference contrast
Microscope: Used for living organisms
-Darkflield -Phase-contrast -Differential interference contrast -Confocal
Microscope: Two beams of light are split to provide contrasting colors
-Differential interference contrast
Microscope: Specimen is a bright color on a dark background
-Fluorescence
Stain outcome: Endospore stain Endospores Vegetative cells
-Green -Red
Microscope: Improved visualization of internal structures
-Phase-contrast -Differential interference contrast
Stain outcome: Gram stain Gram-positive Gram-negative
-Purple -Red
Microscope: Gives detailed 3-D views of the surface
-Scanning electron
Microscope: Uses electrons
-Scanning electron -Transmission electron
Microscope: Ultrathin section imaged to give detailed information on internal structures
-Transmission electron
Scanning Electron
-Uses electrons -Specimens are stained -Gives detailed 3-D views of the surface
Transmission Electron
-Uses electrons -Specimens are stained -Ultrathin section imaged to give detailed information on internal structures
Differential interference contrast
-Uses light -Specimens are not stained -Two beams of light are split to provide contrasting colors -Used for living organisms -Improved visualization of internal structures
Darkfield
-Uses light -Specimens are not stained -Used for living organisms -Specimen is light (white) on a dark background
Phase-contrast
-Uses light -Specimens are not stained -Used for living organisms -Specimen is light (white) on a dark background -Improved visualization of internal structures
Fluorescence
-Uses light -Specimens are stained -Specimen is a bright color on a dark background
Confocal
-Uses light -Specimens are stained -Used for living organisms -One plane at a time is imaged to reconstruct a 3-D view
Compound light microscope
-Uses light -Specimens are stained -Uses Immersion oil
Which of the following is NOT visible through a compound light microscope? 15-µm white blood cell 1.5-mm tick 5-µm nucleus 0.02-µm ribosome
0.02-µm ribosome
A virus measures 100 nm in length. What is its length in μm? 1 μm 0.1 μm 0.001 μm 0.01 μm 10 μm
0.1 μm
Which type of stain is most useful in helping clinicians to decide which antibiotic to prescribe for a bacterial infection? flagella stain negative stain Gram stain simple stain endospore stain
Gram stain
Bacterial smears are fixed before staining to make their walls permeable. affix the cells to the slide. accept stain. make the cells visible.
affix the cells to the slide.
What are substances that are naturally produced and effective against other microorganisms? antibiotics synthetic drugs chemotherapeutic agents vaccines
antibiotics
Which type of light microscopy is used to visualize stained specimens? binocular phase-contrast darkfield brightfield compound
brightfield
You are performing a Gram stain on gram-negative bacteria and you stop after the decolorizer step. What is the appearance of the bacteria at this point? purple red colorless brown
colorless
Which of the following is NOT a type of a compound microscope? fluorescent microscope electron microscope darkfield microscope brightfield microscope
electron microscope
Place these structures of the compound light microscope in the order that light passes through them on the way to the observer's eyes: (1) condenser, (2) ocular lens, (3) light source, (4) specimen, (5) objective lens. light source → specimen → condenser → objective lens → ocular lens light source → condenser → objective lens → specimen → ocular lens ocular lens → condenser → specimen → light source → objective lens light source → condenser → specimen → objective lens → ocular lens
light source → condenser → specimen → objective lens → ocular lens
A student is observing a Gram stain with the 100× (oil immersion) lens. The image appears cloudy and dark. Which of the following actions will NOT increase the clarity of the image? adjusting the condenser to better focus light through the specimen using lens paper to clean any dirt or old oil off the lenses lowering the stage to increase the distance between the object and the objective lens increasing the amount of light passing through the condenser using the diaphragm
lowering the stage to increase the distance between the object and the objective lens
Which of the following is the most convenient and appropriate unit for expressing the size of an average bacterial cell? micrometer nanometer centimeter millimeter
micrometer
What branch of biology focuses on studying fungi (examples would be molds, yeast and mushrooms)? bacteriology genomics immunology virology mycology
mycology
Which of the following types of microscopy is most useful for viewing the internal structures of unstained specimens? fluorescence phase-contrast brightfield electron confocal
phase-contrast
Which of the following types of microscopy is most useful for viewing the internal structures of unstained specimens? phase-contrast brightfield confocal fluorescence electron
phase-contrast
Which of the following places the steps in the correct sequence? 1-Staining 2-Making a smear 3-Fixing 1-2-3 3-2-1 2-3-1 1-3-2 The order is unimportant.
2-3-1 2-Making a smear 3-Fixing 1-Staining
When an object is viewed through a light microscope with oculars that magnify 20× and a high-power objective lens that magnifies 100×, what is the total magnification of the object? 200× 800× 1000× 2000×
2000×
Place these structures of the compound light microscope in the order that light passes through them on the way to the observer's eyes: (1) condenser, (2) ocular lens, (3) illuminator, (4) specimen, (5) objective lens. SHOW HINT 2-1-4-3-5 3-4-1-5-2 3-1-4-5-2 3-1-5-4-2
3-1-4-5-2
What is the correct sequence for the light path in a compound light microscope? 1. specimen 2. ocular lens 3. objective lens 4. light source 5. condenser 4, 1, 2, 3, 5 4, 5, 3, 2, 1 4, 5, 3, 1, 2 4, 5, 1, 2, 3 4, 5, 1, 3, 2
4, 5, 1, 3, 2
What is the total magnification for an image produced using a microscope with the following characteristics: an ocular lens of 10X, a numerical aperture of 0.1 and the 40X objective lens in place? 10X 40X 100X 400X 1,000X
400X
Consider the following situations, and determine when a simple stain could be used instead of a Gram stain. A microbiologist is trying to determine whether a specimen contains bacteria or fungi. An unknown species of bacteria is being characterized and identified. A specimen is suspected to contain multiple species of bacteria. A wound specimen is being examined.
A microbiologist is trying to determine whether a specimen contains bacteria or fungi
Consider the following situations, and determine when a simple stain should be used instead of a Gram stain. A wound specimen is being examined. A microbiologist is trying to determine whether an organism has flagella. A specimen is being examined in which the presence of multiple species of bacteria is suspected. An unknown species of bacteria is being characterized and identified.
A microbiologist is trying to determine whether an organism has flagella.
Which type of microscope would allow the viewer to see ribosomes inside a cell? A scanning electron microscope A light microscope A light microscope, transmission electron microscope, and scanning electron microscope can all view ribosomes inside a cell. A transmission electron microscope
A transmission electron microscope
The acid-fast stain differs from the Gram stain procedure in the decolorizing agent used. What is the reagent used in an acid-fast stain, and why is it necessary? Acetone-alcohol is used as the decolorizer in order to enhance the primary stain. Acid-alcohol is used to remove the primary stain from bacteria that do not have waxy cell walls. Alcohol is used as the decolorizer in order to penetrate the bacterial capsule. Acetone is used as the decolorizer to penetrate the endospore.
Acid-alcohol is used to remove the primary stain from bacteria that do not have waxy cell walls.
What kinds of organisms are responsible for providing food for other living organisms? Hint: think photosynthesis, where the sun's energy is used to make sugar. (There is more than one correct answer.) Algae Plants Viruses Animals Cyanobacteria
Algae Plants Cyanobacteria
In the gram stain, what color are the cells after the addition of the crystal violet and iodine? All cells are pink/red. Gram-positive are purple and gram-negative are pink/red. Gram-positive are purple and gram-negative are colorless. All cells are purple. Crystal violet isn't used in the gram stain.
All cells are purple.
A student creates a Gram stain on a bacterial sample that has a mix of gram-negative and gram-positive organisms. The student accidentally forgets the decolorizer step. What would the outcome of the Gram stain be? All organisms would appear purple (gram-positive). The Gram stain would show pink (gram-negative bacteria) and purple (gram-positive bacteria). All organisms would appear pink (gram-negative). All organisms would appear colorless.
All organisms would appear purple (gram-positive).
Why is a specimen smaller than 200 nm not visible with a light microscope? It is too easy to lose on the stage. The lenses only go to 100 X magnification power. Anything smaller than 200 nm cannot interact with visible light. Visible light is only good at wavelengths below 390 nm.
Anything smaller than 200 nm cannot interact with visible light.
Which of the following statements comparing electron microscopy and light microscopy is FALSE? Images produced by light microscopes can be in color, whereas electron microscope images are black and white unless they are artificially colored. Both the electron microscope and the light microscope use the same wavelengths for illumination. Electron microscopes can allow examination of viruses and internal cell structures, whereas light microscopes are limited to objects that are 0.5 micrometers and larger. The electron microscope has greater resolution than the light microscope.
Both the electron microscope and the light microscope use the same wavelengths for illumination.
A negative stain, which uses an acidic dye, is used to visualize what structure? Endospores Flagella Capsule Cell wall Plasma membrane
Capsule
Endospores will appear __________ in the gram stain. Purple Pink/red Green Colorless
Colorless
Which is the most critical step in the gram stain procedure? Primary stain Mordant Decolorizer Counterstain
Decolorizer
Who first came up with vaccination by using cowpox infection to protect from smallpox? Alexander Fleming Robert Hooke Edward Jenner John Needham Joseph Lister
Edward Jenner
Why do electron microscopes have higher resolving power than light microscopes? The copper grid used in electron microscopy provides enhanced resolution. They are capable of producing 3-dimensional images, which light microscopes cannot do. Electrons have a smaller wavelength than visible light, leading to higher resolution. The fluorescent screen adds another magnification step.
Electrons have a smaller wavelength than visible light, leading to higher resolution.
Bacterial motility and flagellar movement can readily be viewed using transmission electron microscopy. True False
False
Fluorescence microscopy uses a fluorescent light. True False
False
Magnification is the quality of the microscope that allows one to distinguish between two points that are very close together. True False
False
Before cells are stained, the specimen must be fixed. Fixing a specimen accomplishes all of the following EXCEPT which one? Fixation attaches cells to the slide so that they will not wash off during the staining process. Fixation differentiates the various cells being observed. Fixation kills the cells that are being stained for observation. Fixation preserves cellular structure in the natural state, with minimum distortion.
Fixation differentiates the various cells being observed
Protozoa have which of the following structures for motility? (There is more than one correct answer) Flagella Endoflagella Cilia Pseudopods Axial filaments
Flagella Cilia Pseudopods
What is the role of iodine in the Gram stain process? Iodine is a mordant in the Gram stain technique, which functions to intensify the primary stain. Iodine is the decolorizer removing the primary stain after the first step in the Gram stain technique. Iodine is a basic purple dye, which acts as the primary stain in the Gram stain technique. Iodine is a pink dye that acts as the primary stain in the Gram stain technique.
Iodine is a mordant in the Gram stain technique, which functions to intensify the primary stain.
What is meant by light rays being divergent? It is coming together to a focused beam It is heading upwards It is spreading out
It is spreading out
What is the role of lenses in microscopy? Lenses focus either light or electrons to create a magnified image of a specimen. Lenses increase the contrast to determine structural differences in stained specimens. Lenses are only used to magnify specimens that are smaller than whole red blood cells.
Lenses focus either light or electrons to create a magnified image of a specimen.
Which scientist is responsible for developing aseptic technique? Joseph Lister Louis Pasteur Francesco Redi Lazaro Spallanzani Anton van Leeuwenhoek
Louis Pasteur
Koch's postulates are used to determine the cause of illness related to disease transmission. What is the first step? Culture the blood or other body fluid from a diseased animal to determine the microorganism characteristics. Obtain a sample of blood or other body fluid from a diseased animal. Isolate microorganisms from the blood of healthy animals. Compare the microorganisms from a sick animal to those obtained from a healthy animal. Inject a sample of blood or other body fluid from a diseased animal into a healthy animal.
Obtain a sample of blood or other body fluid from a diseased animal.
What is the name for an organism that causes an infection? Protozoan Pathogen Mycoplasma Normal flora Biofilm
Pathogen
Acid-fast Stain: Primary stain Mordant Decolorizer Counterstain
Primary stain- Carbolfuchsin Mordant- Steam heat Decolorizer- Acid-alcohol Counterstain- Methylene blue
Gram stain: Primary stain Mordant Decolorizer Counterstain
Primary stain- Crystal violet Mordant- Grams iodine Decolorizer- Alcohol Counterstain- Safranin
Endospore Stain: Primary stain Mordant Decolorizer Counterstain
Primary stain- Malachite green Mordant- Steam heat Decolorizer- Water Counterstain- Safranin
Which of the following is a lens found on electron microscopes but not on light microscopes? Condenser lens Projector lens Objective lens Eyepiece lens
Projector lens
When properly subjected to an acid fast stain protocol, bacteria in the genus Mycobacterium appear __________. When using a 10× ocular lens and a 40× objective, the total magnification achieved is __________. Red; 400X Blue; 1000X Purple; 400X Red; 1000X
Red; 400X
Which scientist suggested the theory of biogenesis, that cells come from cells? Alexander Fleming Robert Hooke Edward Jenner John Needham Rudolph Virchow
Rudolph Virchow
A student completes a Gram stain on a bacterial smear that has a mix of gram-negative and gram-positive organisms. The student stops the procedure without adding safranin. Predict the appearance of the Gram positive organisms and the Gram negative organisms. The gram-positive organisms would appear purple, and the gram-negative organisms would be colorless. The Gram stain would show pink (gram-negative) and purple (gram-positive) bacteria. All organisms would appear pink (gram-negative). All organisms would appear colorless.
The gram-positive organisms would appear purple, and the gram-negative organisms would be colorless.
In a typical brightfield microscope, at which point does magnification begin? The stage The ocular lens The lamp The condenser lens The objective lens
The objective lens
Which of the following statements is NOT true for both TEM and SEM? Both can be used to view specimens smaller than 0.2 micrometers. The specimen must be sectioned before viewing. The illuminating source is an electron beam. The microscope is focused using electromagnetic lenses. Black-and-white images are produced.
The specimen must be sectioned before viewing.
What happens to the light rays when they hit the specimen? They are reflected, refracted, or absorbed by the specimen. They are absorbed by the stage. They are focused into a small area towards the objective lens. They are diverted to the ocular lens.
They are reflected, refracted, or absorbed by the specimen.
Which of the following is a characteristic shared by both electron and light microscopes? Both microscopes have a resolving power of 0.01 nm. They both employ the use of objective lenses. They both utilize white light to magnify the specimen. Both microscopes require an internal camera to visualize the specimen
They both employ the use of objective lenses.
What is the fate of the electrons that interact with a specimen in an electron microscope? They may be absorbed, reflected, or refracted by the specimen. They are reflected by the specimen. They are absorbed by the specimen They are refracted by the specimen.
They may be absorbed, reflected, or refracted by the specimen.
What is the purpose of heat fixing after smear preparation? To attach the bacterial cells to the glass slide, kill and preserve their structure. To weaken the cell wall so they can pick up the stain. To ensure there are not any contaminating organisms present. To provide contrast to the slide.
To attach the bacterial cells to the glass slide, kill and preserve their structure.
What is the role of the ocular lens? To adjust the wavelength of light To do the bulk of the magnification To recreate the image in the viewer's eye To focus the light to a high intensity in a small area
To recreate the image in the viewer's eye
Which of the following types of microscopes can provide the greatest magnification? Compound light microscope Phase-contrast microscope Confocal microscope Scanning electron microscope Transmission electron microscope
Transmission electron microscope
Bacterial cells that are acid-fast will stain purple with the gram stain. True False
True
Bacterial smears should be fixed to the slide before all staining procedures. True False
True
Biofilms are more resistant to antibiotics than free-living microorganisms. True False
True
Flagella are too small to be seen with the light microscope when stained by the Gram stain protocol. True False
True
Immersion oil acts to decrease refraction of light rays and thus increase resolution. True False
True
The Gram stain is important in medical microbiology because the results help physicians select appropriate antibiotics for treatment. True False
True
The counterstain used in the Gram stain is a basic dye. True False
True
Which of the following staining procedures is matched with the principal use for that stain? negative stain used to differentiate cell wall components acid-fast stain for microbes with waxy cell walls flagella stain used to distinguish dormant structures formed during adverse environmental conditions endospore stain to visualize flagella
acid-fast stain for microbes with waxy cell walls
Which of the following pairs is correctly matched? scanned-probe microscope and internal bacterial structures atomic force microscopes and DNA light microscope and viruses transmission electron microscope and ticks
atomic force microscopes and DNA
Which of the following are considered the basic or most common shapes of bacteria? (This question has more than one correct answer) bacillus coccus spiral rectangular star-shaped
bacillus coccus spiral
Which of the following measurements is correctly matched with microorganisms of that size? bacteria--10 nanometers viruses--10 micrometers bacteria--2 micrometers viruses--1 centimeter
bacteria--2 micrometers
Which microscope is most useful for visualizing a biofilm (think about this, you want to see it in its natural state and also see the full depth of the community of microorganisms)? phase-contrast microscope compound light microscope transmission electron microscope fluorescence microscope confocal microscope
confocal microscope
Which of the following is/are CORRECT regarding naming microorganisms? (This question has more than one correct answer) contains a genus and species name abbreviations are always acceptable should be italicized when typed only a genus name is necessary the genus name should have the first letter capitalized
contains a genus and species name should be italicized when typed the genus name should have the first letter capitalized
What is the correct order for the Gram stain process? crystal violet → safranin → decolorizer → iodine crystal violet → iodine → decolorizer → safranin iodine → crystal violet → decolorizer → safranin malachite green → crystal violet → decolorizer → safranin
crystal violet → iodine → decolorizer → safranin
Which of the following types of microscopy provides advantages for viewing live images? fluorescent microscopy scanning electron microscopy darkfield microscopy transmission electron microscopy
darkfield microscopy
We talked about using the negative stain to visualize the capsule. What else could it be used for with regard to bacterial characteristics (think logically)? determine flagella arrangement determine cell shape determine the gram reaction visualize endospores visualize fimbriae
determine cell shape
Which of the following staining procedures is correctly matched with the principal use for that particular stain? acid-fast stain for microbes with capsules negative stain used to differentiate cell wall components flagella stain used to detect capsules endospore stain to distinguish dormant structures formed during adverse environmental conditions
endospore stain to distinguish dormant structures formed during adverse environmental conditions
Assume you stain Bacillus by applying malachite green with heat and then counterstaining with safranin. Through the microscope, the green structures are cell walls. flagella. endospores. capsules. The answer cannot be determined.
endospores.
Which of the following types of microscopy can be used to specifically identify pathogens (such as Mycobacterium tuberculosis or rabies virus) in specimens? brightfield phase-contrast darkfield fluorescence transmission electron
fluorescence
Your lab partner tells you the bacteria are moving in his Gram-stained smear. You can conclude that __________. the bacteria are gram-negative the bacteria have capsules he did a flagella stain, not a Gram stain he didn't properly fix the smear the bacteria are acid-fast
he didn't properly fix the smear
Which of the following steps is common to both the Gram stain and the acid-fast stain? the application of iodine as a mordant the use of methylene blue as a counterstain acid-alcohol for decolorizing heat fixation of the smear before staining steam exposure for stain penetration
heat fixation of the smear before staining
Which microscope is used to see internal structures of cells in their natural environment while they are alive? fluorescence microscope electron microscope compound light microscope darkfield microscope phase-contrast microscope
phase-contrast microscope
The __________ charge of a basic dye adheres to the __________ charge of bacterial cell surfaces. positive; acidic negative; positive negative; acidic positive; negative positive; basic
positive; negative
The __________ charge of a basic dye adheres to the __________ charge of bacterial cell surfaces. positive; basic positive; acidic positive; negative negative; acidic negative; positive
positive; negative
Making DNA by inserting the genes from one organism into another organism is called __________. genomics immunology virology recombinant DNA technology parasitology
recombinant DNA technology
A measure of the light-bending ability of a sample is called __________. resolution or resolving power refraction or refractive index radioactive reflection reactive
refraction or refractive index
Which of the following kinds of microscopy would be most appropriate for viewing the shape and arrangement of pili or fimbriae on the surface of a bacterial cell? transmission electron microscopy scanning electron microscopy darkfield microscopy phase-contrast microscopy brightfield microscopy
scanning electron microscopy
A student is looking at a bacterial specimen using the oil immersion lens, but has forgotten to put immersion oil on the slide. The specimen will appear somewhat fuzzy and have poor resolution.to have no color. larger than it would if immersion oil was used. smaller than it would if immersion oil was used. the same as it would if the immersion oil was used.
somewhat fuzzy and have poor resolution.
What does resolution mean? the ability of a microscope to stay in focus when the objective lenses are moved from low power to high the ability of a microscope to distinguish fine details and differentiate between two very close objects the total magnification of the visual image seen a measure of the ability of a medium to bend light
the ability of a microscope to distinguish fine details and differentiate between two very close objects
You are viewing a sputum smear that has been stained with an acid-fast stain. On this smear you see 5-micrometer-long red cells. You can conclude that __________. there are acid-fast bacteria in the specimen normal microbiota are acid-fast there are no acid-fast bacteria in the specimen normal microbiota are gram-negative human cells are acid-fast
there are acid-fast bacteria in the specimen
Which of the following kinds of microscopy would be most appropriate for viewing the presence and distribution of mitochondria in a protozoan cell.? brightfield microscopy darkfield microscopy transmission electron microscopy scanning electron microscopy phase-contrast microscopy
transmission electron microscopy
Bacterial cells have an overall negative charge on their surface. If a bacterial smear is stained by a pink, acidic, water-soluble stain and then washed with water, which of the following describes the result that will be observed when viewing the stained slide under a microscope? pink cells unstained cells with no background unstained cells in a pink background purple cells pink cells in a pink background
unstained cells with no background
In a negative staining procedure, the bacterial cells would appear __________ when viewed under a microscope. stained in an unstained background the same color as the background and thus not easily observed unstained in a colored background attracted to the dye used in the staining procedure brightly colored in a contrasting background
unstained in a colored background
Which of the following groups contains acellular particles that must replicate within another host? bacteria archaea protozoa algae viruses
viruses
Acid-fast mycobacteria differ from non-acid-fast bacteria by the presence of __________. In the decolorizing step of the acid-fast stain, __________ is used. endospores; methylene blue capsules; acetone-alcohol peptidoglycan; carbolfuchsin waxy material in their cell walls; acid-alcohol
waxy material in their cell walls; acid-alcohol