2) What structure does light pass through after leaving the condenser in a compound light microscope?
A) ocular lens
B) objective lens
C) specimen
D) illuminator
C
3) Which of the following pairs is mismatched?
A) nigrosin - negative stain
B) methylene blue - simple stain
C) acidic dye - capsule stain
D) basic dye - negative stain
E) crystal violet - simple stain
D
4) Which of the following places the steps of the Gram stain in the correct order?
1-Alcohol-acetone
2-Crystal violet
3-Safranin
4-Iodine
A) 1-2-3-4
B) 2-1-4-3
C) 2-4-1-3
D) 4-3-2-1
E) 1-3-2-4
C
5) Which of the following pairs is mismatched?
A) alcohol-acetone — decolorizer
B) crystal violet — basic dye
C) safranin — acid dye
D) iodine — mordant
E) carbolfuchsin — basic dye
C
6) Which of the following is NOT true regarding the acid-fast stain?
A) It is used to identify members of the genus Mycobacterium.
B) Acid-fast cells retain the primary dye after treatment with acid-alcohol.
C) If cells are acid-fast, they are gram-negative.
D) Acid-fast cells appear red in a completed acid-fast stain.
E) Non-acid-fast microbes appear blue in a completed acid-fast stain.
C
7) The purpose of a mordant in the Gram stain is to
A) remove the simple stain.
B) make the bacterial cells larger.
C) make the flagella visible.
D) prevent the crystal violet from leaving the cells.
E) make gram-negative cells visible.
D
8) Which of the following places the steps in the correct sequence?
1-Staining
2-Making a smear
3-Fixing
A) 1-2-3
B) 3-2-1
C) 2-3-1
D) 1-3-2 E) The order is unimportant.
C
9) The negative stain is used to
A) visualize endospores.
B) determine Gram reaction.
C) determine flagella arrangement.
D) visualize capsules.
E) determine cell size.
D
10)Simple staining is often necessary to improve contrast in which microscope?
A) compound light microscope
B) phase-contrast microscope
C) darkfield microscope
D) fluorescence microscope
E) electron microscope
A
11)Which microscope is used to see internal structures of cells in a natural state?
A) compound light microscope
B) phase-contrast microscope
C) darkfield microscope
D) fluorescence microscope
E) electron microscope
B
12)Which microscope uses visible light?
A) confocal microscope
B) differential interference contrast microscope
C) fluorescence microscope
D) scanning acoustic microscope
E) scanning electron microscope
B
13)Which microscope achieves the highest magnification and greatest resolution?
A) compound light microscope
B) phase-contrast microscope
C) darkfield microscope
D) fluorescence microscope
E) electron microscope
E
14) In using this microscope, the observer does NOT look directly at an image through a lens.
A) compound light microscope
B) phase-contrast microscope
C) darkfield microscope
D) fluorescence microscope
E) electron microscope
E
16) A virus measures 100 nm in length. What is its length in μm?
A) 10 μm
B) 1 μm
C) 0.1 μm
D) 0.01 μm
E) 0.001 μm
C
18) A microorganism measures 5 μm in length. Its length in mm would be
A) 500 mm.
B) 50 mm.
C) 0.5 mm.
D) 0.05 mm.
E) 0.005 mm.
E
19) Which of the following correctly traces the path of light through the compound microscope?
A) light source; condenser; specimen; objective lens; ocular lens
B) condenser; light source; specimen; ocular lens; objective lens
C) light source; specimen; condenser; objective lens; ocular lens
D) condenser; light source; specimen; objective lens; ocular lens
E) light source; condenser; objective lens; specimen; ocular lens
A
20) Figure 3.1 In Figure 3.1, line c points to the microscopes
A) illuminator.
B) condenser.
C) ocular lens.
D) objective lens.
B
23)Which microscope is most useful for visualizing a biofilm?
A) compound light microscope
B) phase-contrast microscope
C) fluorescence microscope
D) scanning acoustic microscope
E) transmission electron microscope
D
25) 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?
A) purple
B) red
C) colorless
D) brown
A
26) You are performing a Gram stain on gram-negative bacteria and you stop after the addition of the mordant. What is the appearance of the bacteria at this point?
A) purple
B) red
C) colorless
D) brown
A
27) 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?
A) purple
B) red
C) colorless
D) brown
C
28) 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?
A) purple
B) red
C) colorless
D) brown
A
29) Which type of stain is most useful in helping clinicians to decide which antibiotic to prescribe for a bacterial infection?
A) negative stain
B) simple stain
C) Gram stain
D) endospore stain
E) flagella stain
C
31) What is the total magnification of a specimen viewed with a 10x ocular lens and a 45x objective lens?
A) 4.5x
B) 10x
C) 45x
D) 100x
E) 450x
E
36) Which microscope is used to see detail of a 300-nm virus?
A) fluorescence microscope
B) phase-contrast microscope
C) darkfield microscope
D) DIC microscope
E) electron microscope
E
38) Which step in the Gram stain is the critical step in differentiating gram-positive cells from gram-negative cells?
A) safranin
B) alcohol-acetone
C) iodine
D) crystal violet
B
40) Which microscope is best used for observing the surfaces of intact cells and viruses?
A) phase-contrast microscope
B) darkfield microscope
C) fluorescence microscope
D) brightfield microscope
E) scanning electron microscope
E
41) Bacterial smears are fixed before staining to
A) affix the cells to the slide.
B) make their walls permeable.
C) accept stain.
D) make the cells visible.
A
43) 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
A) smaller than it would if immersion oil was used.
B) larger than it would if immersion oil was used.
C) somewhat fuzzy and have poor resolution.
D) the same as it would if the immersion oil was used.
E) to have no color.
C
44) The purpose of the ocular lens is to
A) improve resolution.
B) magnify the image from the objective lens.
C) decrease the refractive index.
D) increase the light.
E) decrease the light.
B
45) In microscopy, the term resolution
A) refers to the ability to distinguish fine structure and detail in a specimen.
B) is the same as the total magnification of a specimen.
C) is improved when longer wavelengths of light are employed.
D) is only observed in stained specimens.
E) refers to magnification when using the electron microscope.
A