Which of the following is NOT equal to 1mm?
100 um
What structure does light pass through after leaving the condenser in a compound light microscope?
a specimen
Which of the following pairs is mismatched?
basic dye-negative stain
Which of the following places the steps of the Gram stain in the correct order? (CIAS)
Crystal violet, Iodine, Alcohol-acetone, Safranin
Which of the following pairs is mismatched?
safranin - acid dye
Which of the following is NOT true regarding the acid-fast stain?
If cells are acid-fast they are gram-negative
The purpose of a mordant in the Gram stain is to
prevent the crystal violet from leaving the cells
Which of the following places the steps in the correct sequence?
Making a smear, Fixing, Staining
MFS
The negative stain is used to
visualize capsules
Simple staining is often necessary to improve contrast in which microscope?
compound light microscope
Which microscope is used to see internal structures of cells in a natural state?
phase-contrast microscope
Which microscope uses visible light?
differential interference contrast microscope
Which microscope achieves the highest magnification and greatest resolution?
electron microscope
In using this microscope the observer does NOT look directly at an image through a lens
electron microscope
This microscope produces an image of a light cell against a dark background; internal structures are NOT visible.
darkfield microscope
A virus measures 100 nm in length. What is its length in um?
.1 um
Which of the following in NOT useful for observing living cells?
scanning electron microscope
A microorganism measures 5 um in length. Its length in mm would be
0.005 mm
Which of the following correctly traces the path of light through the compound microscope?
light source; condenser; specimen; objective lens; ocular lens LCSObOc
In Figure 3.1, line "c" points to the microscope's
condenser
Which microscope can be used to visualize DNA or botulinum toxin?
scanning tunneling microscope
Which microscope is used to observe a specimen that emits light when illuminated with an ultraviolet light?
fluorescence microscope
Which microscope is most useful for visualizing a biofilm?
scanning acoustic microscope
Which microscope takes advantage of differences in the refractive indexes of cell structures?
phase-contrast microscope
You are performing a Gram stain on gram-positive bacteria and you stop after the addition of the first dye. What is the appearance of the bacteria at this point?
purple
You are performing a Gram stain on a gram-negative bacteria and you stop after the addition of the mordant. What is the appearance of the bacteria at this point
purple
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?
colourless
You are performing a Gram stain on gram-positive bacteria and you stop after the addition of the counterstain. What is the appearance of the bacteria at this point?
purple
Which type of stain is most useful in helping clinicians to decide which antibiotic to prescribe for a bacterial infection?
Gram Stain
Which of the following pairs is mismatched?
fluorescence microscope-uses a fluorescent light
What is the total magnification of a specimen viewed with a 10x ocular lens and a 45x objective lens?
450x
You are studying a cell structure that is approximately 100 nm in size. Which of the following provides the lowest magnification you can use to see this structure?
scanning electron microscope
Which microscope uses two beams of light to produce a three-dimensional color image?
DIC microscope
Which microscope is used to see intracellular detail in a living cell?
two-photon microscope
Which microscope is used to observe viruses and the internal structure of thinly sectioned cells?
transmission electron microscope
Which microscope is used to see detail of a 300-nm virus?
electron microscope
Assume you stain Bacillus by applying malachite green with heat and then counterstaining with safranin. Through the microscope, the green structures are
endospores
Which step in the Gram stain is the critical step in differentiating gram-positive cells from gram-negative cells?
alcohol-acetone
You find colorless areas in cells in a gram-stained smear. What should you apply next?
an endospore stain
Which microscope is best used for observing the surfaces of intact cells and viruses?
scanning electron microscope
Bacterial smears are fixed before staining to
affix the cells to the slide
The resolution of a microscope can be improved by changing the
wavelength of light
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
The purpose of the ocular lens is to
magnify the image from the objective lens
In microscopy, the term resolution
refers to the ability to distinguish fine structure and detail in the specimen
The counterstain used in the Gram stain is a basic dye
True
In a completed Gram stain, gram-negative bacteria are colourless
False
In a completed Gram stain, gram-positive bacteria are purple
True
If acid-fast bacteria are stained with the Gram stain, they will stain gram-negative.
False
The limit of resolution of the compound microscope illuminated with visible light is approximately 0.2 um.
True
Both phase-contrast microscopy and differential interference contrast microscopy are used to view the internal structures of cells without staining
True
Cells are viewed in darkfield microscopy appear similar to those stained with the negative stain
True
The capsules and flagella of bacteria can be observed in gram-stained smears.
False
The greater the resolution of the electron microscope compared to the compound microscope is due to the longer wavelengths of the electrons used to examine specimens
False
Scanned probe microscopy is used to examine fine detail of molecular complexes, such as blood clots, or molecules, such as DNA
True
Which microscope is used to observe a specimen that emits light when illuminated with an ultraviolet light?
fluorescence microscope