1. Compound brightfield microscopy consists of two __________________.
A. | planes of imagery |
B. | light sources |
C. | lens systems |
D. | fields of view |
ANS: C
A compound brightfield microscope consists of two lens systems and a single light source. The first lens system is located in the objectives (i.e., 4×, 10×, 40×, 100×) and produces the primary image. The second lens system is located in the oculars (i.e., 10×).
Cognitive Level: 1
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PTS: 1
2. As total magnification increases, field of view:
A. | Increases |
B. | Decreases |
C. | Remains the same |
D. | Changes exponentially |
ANS: B
The eyepiece not only magnifies the image but also determines the FOV. The formula for determining the FOV is: FOV = Field number ÷ M, where the Field number is indicated on the ocular and M is the magnification of the objective used and any additional optics, not including magnification attributed to the eyepiece.
Cognitive Level: 2
Reference:
PTS: 1
3. A substance that refracts light in two directions is said to be:
A. | Refractive |
B. | Parfocal |
C. | Polarizing |
D. | Birefringent |
ANS: D
The term birefringent (or doubly refractile) refers to the ability of a substance to refract light in two different directions. Parfocal refers to objective lenses that remain in focus when switching from one objective to another objective of higher or lower magnification. Polarizing microscopy uses polarized light to illuminate the specimen and is used to identify and classify birefringent specimens. Refractive refers to a change in direction of a wave due to a change in speed.
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4. Color fringes surrounding objects under microscopic review are referred to as a _____________ and can be corrected by using a ____________ objective.
A. | chromatic aberration, plan |
B. | spherical aberration, Ph |
C. | darkfield aberration, fluorescent |
D. | polarizing aberration, phase-contrast |
ANS: A
Chromatic aberration, or chromatic distortion, refers to the unequal refraction of light rays because different wavelengths of light bend at different angles. The lens is unable to focus all of the colors to the same focal plane, and the result is an image with color fringes. Spherical aberration refers to unequal refraction of light rays as they pass through the lens, resulting in many focal points and a blurred or fuzzy image. Plan refers to flat field; Ph refers to phase microscopy lens, and so on.
Cognitive Level: 1
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PTS: 1
5. The microscopic component that gathers and focuses the illumination light onto the specimen being viewed is the:
A. | field diaphragm |
B. | condenser |
C. | objective |
D. | illumination system |
ANS: B
The condenser gathers and focuses the light onto the specimen. The field diaphragm controls the diameter of the light beam that strikes the specimen, eliminating stray light. The objective comprises a system of lenses on the revolving nosepiece and produces the primary image magnification of the specimen. The illumination system refers to the light source.
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6. A specimen is collected directly onto a glass slide from a suspected syphilis lesion and will be examined for spirochetes under which type of microscope?
A. | Phase-contrast |
B. | Polarizing |
C. | Darkfield |
D. | Fluorescence |
ANS: C
Darkfield microscopy is useful for viewing live specimens (i.e., organisms such as yeast, fungi, blood cells, and spirochetes). These types of specimens are typically colorless, and when viewed using darkfield microscopy, the image is illuminated against a dark background.
Cognitive Level: 2
Reference:
PTS: 1
7. Secondary image magnification in microscopy occurs in which of the following?
A. | Eyepiece |
B. | Condenser |
C. | Aperture diaphragm |
D. | Resolution |
ANS: A
In microscopy, the eyepiece, or ocular, is part of the system of lenses. It produces the secondary image magnification of the specimen. The primary image is produced by the objective lenses.
Cognitive Level: 1
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PTS: 1
8. The field of view is determined by which of the following?
A. | Objective |
B. | Eyepiece |
C. | Field diaphragm |
D. | Condenser |
ANS: B
The field of view is determined by the eyepiece of the microscope. The diameter of the field varies with the eyepiece field number and the objective magnification used, as expressed in the formula FOV = Field number ÷ Magnification.
Cognitive Level: 1
Reference:
PTS: 1
9. The technician has been given the assignment to select two new microscopes to add to five microscopes currently in use. Which of the following is most important in ensuring standardized reporting of results?
A. | Field number |
B. | Parcentric |
C. | Parfocal |
D. | Resolving power |
ANS: A
Having the same field number for all microscopes used in the same laboratory that reports out the number of elements observed per FOV is crucial for ensuring standardization of microscopic results. Different field numbers will result in different diameters being viewed between microscopes, resulting in variations in reporting.
Cognitive Level: 2
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10. The best resolution in microscopy is achieved when the:
A. | Field of view increases |
B. | Numeric aperture increases |
C. | Condenser NA is greater than the objective NA |
D. | Distance between two points increases |
ANS: B
In microscopy, resolution is the ability of the lens system to reveal fine detail and is determined by the numeric aperture (NA). As the NA increases, the resolution distance decreases, and the viewer can distinguish a smaller distance between two distinct points.
Cognitive Level: 2
Reference:
PTS: 1
11. The technician asked her co-worker to look at a slide she was viewing under the microscope. When the co-worker looked at the slide, his vision seemed fuzzy, so he immediately adjusted the:
A. | Coarse adjuster |
B. | Fine adjuster |
C. | Diopter adjustment |
D. | Light intensity |
ANS: C
The interpupillary distance of the eyepiece tubes must be adjusted to accommodate differences between individual viewers. In addition, vision in the two eyes is not usually the same, and the viewer must adjust the diopter adjustment in each eyepiece until a sharp image is seen. The settings for one viewer most likely will not suit a different viewer, and adjustments must be made for each individual.
Cognitive Level: 2
Reference:
PTS: 1
12. When deciding whether to wear glasses while performing microscopy procedures, the examiner must determine whether the glasses have:
A. | Spherical correction |
B. | Toric correction |
C. | Birefringent correction |
D. | Convex correction |
ANS: B
Individuals with astigmatism that requires a toric lens for correction should wear their glasses when performing microscopy, because the microscope does not compensate for this. To determine whether the eyeglasses have toric correction, the person should hold the glasses in front of some lettering at arm’s length to see whether the glasses reduce or magnify the lettering. If the lettering changes in length or width when the glasses are rotated 45 degrees, the eyeglasses have toric correction and should be worn.
Cognitive Level: 1
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13. Maximum resolution, contrast, and definition of the specimen are achieved by properly using which of the following during microscopy?
A. | Condenser |
B. | 100× objective |
C. | Aperture diaphragm |
D. | Fine adjuster |
ANS: C
The aperture diaphragm controls the angle of the illumination light presented to the specimen and objective lens in use. It must be properly adjusted to achieve maximal resolution, contrast, and definition of the specimen.
Cognitive Level: 2
Reference:
PTS: 1
14. It is important to minimize stray light by properly adjusting the:
A. | Oculars |
B. | Working distance |
C. | Condenser |
D. | Field diaphragm |
ANS: D
The field diaphragm controls the diameter of the light beams that strike the specimen, thereby reducing stray light.
Cognitive Level: 2
Reference:
PTS: 1
15. To achieve maximal viewing when moving from low power 10× to high power 40×, the examiner should:
A. | Increase illumination |
B. | Decrease illumination |
C. | Maintain same illumination |
ANS: A
Moving from low power 10× to high power 40× means changing from a low NA to a higher NA, which requires more illumination. Therefore, the condenser and aperture diaphragm should be adjusted to increase the amount of light to be focused on the specimen.
Cognitive Level: 2
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16. While scanning a slide at 40×, the technician sees an abnormal cell. The technician flips the objective off the slide, adds a drop of oil, and moves the 100× objective into place. The cell is no longer in the field, because the objective is not________________.
ANS: B
Parcentric is a characteristic of the objective lens that relates to the ability to retain the same central FOV when the user switches from one objective to another. Parfocal refers to the ability of the object to remain in focus regardless of the objective used.
Cognitive Level: 1
Reference:
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17. Eyepieces and objectives function together to determine:
A. | Field of view and resolution |
B. | Field number and working distance |
C. | Field of view and total magnification |
D. | Field number and field of view |
ANS: C
The FOV is determined by a round baffle or ridge located inside the ocular, and its numeric value is the field number. Total magnification is the magnification of the eyepiece times the magnification of the objective used.
Cognitive Level: 2
Reference:
PTS: 1
18. Which of the following objectives has the highest resolution and requires use of a coverslip?
A. | HR 20×/0.60
¥/0.17 |
B. | E Plan
100×/1.40
160/0.17 |
C. | S40/0.60
¥/0.17 |
D. | Plan Fluor
40×/-
¥/0.11-0.23 |
E. | Plan Apo
100×/0.95
160/- |
ANS: B
The number after the objective magnification (100×) is the NA, and the higher the number, the greater the resolution. If a coverslip is required, it is engraved on the microscope after the tube length (160 or ¥). Option B has the highest NA (1.40) and requires a coverslip (0.17).
Cognitive Level: 2
Reference:
PTS: 1
19. Stationary black specks in the FOV indicate which of the following?
A. | Mascara on the oculars |
B. | Damaged lens |
C. | Dirty objective |
D. | Dusty coverslip |
ANS: C
If the eyepiece is dirty, the viewer will see specks, and if the eyepiece is rotated, the specks will move. If the objective lens is dirty, the specks will remain stationary and disappear when using a different objective.
Cognitive Level: 2
Reference:
PTS: 1
20. Optimal adjustment of the condenser and aperture diaphragm when using Kohler illumination is important in which type of microscope?
A. | Phase-contrast |
B. | Brightfield |
C. | Fluorescent |
D. | Polarizing |
ANS: B
Brightfield microscopy uses Kohler illumination, which requires adjustment of the condenser and aperture diaphragm. The other types of microscopy may require additional procedures to ensure optimal viewing; for example, phase-contrast microscopy requires alignment of the phase rings.
Cognitive Level: 2
Reference:
PTS: 1
21. Phase-contrast microscopy presents light to the specimen:
A. | From the central light annulus of the annular diaphragm of the condenser |
B. | As vibrational light in one direction or plane |
C. | By converting differences in the optical path through the specimen |
D. | To create an bright image against a dark background |
ANS: A
In phase-contrast microscopy, the specimen receives light only from the central light annulus of the annular diaphragm of the condenser. In brightfield microscopy, undiffracted and diffracted light rays are superimposed to produce the image being magnified.
Cognitive Level: 2
Reference:
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22. Polarizing microscopy is useful in identifying ____________________.
A. | bipolar stained organisms |
B. | birefringent substances |
C. | specimens containing living organisms |
D. | unstained specimens |
ANS: B
Polarizing microscopy is used to identify birefringent substances. Using a red compensator or full wave plate allows for identification of crystals based on their negative or positive birefringence.
Cognitive Level: 2
Reference:
PTS: 1
23. Which type of microscope is used to visualize three-dimensional images?
A. | Phase contrast |
B. | Modulation contrast |
C. | Differential interference contrast |
D. | A and B |
E. | B and C |
ANS: E
Modulation contrast microscopy and differential interference contrast microscopy allow for 3-D visualization of images.
Cognitive Level: 1
Reference:
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24. Which type of microscopy uses an excitation filter and a barrier filter?
A. | Phase contrast |
B. | Differential interference contrast |
C. | Darkfield |
D. | Fluorescence |
ANS: D
Fluorescence microscopy uses light of a selected wavelength that is presented to the specimen. If a fluorescent substance is present, it will absorb the light and emit light at a longer wavelength. Any light emitted is transmitted to the eyepiece. Two filters are used to accomplish this: an excitation filter, which selects the wavelength of the excitation light presented to the specimen, and a barrier filter, which selects a specific wavelength of light to be emitted from the specimen.
Cognitive Level: 1
Reference:
PTS: 1
25. Proper cleaning of a microscope requires all of the following except:
A. | Lens paper |
B. | Lint-free tissues |
C. | Air syringe |
D. | Brush |
ANS: B
Even lint-free tissues may scratch the lenses. Only lens paper should be used on the optical surfaces.
Cognitive Level: 2
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