Edition
Chapter 01: Microscopy
Test Bank
MULTIPLE CHOICE
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
Reference:
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.
Cognitive Level: 1
Reference:
, PTS: 1
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
Reference:
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.
Cognitive Level: 1
Reference:
PTS: 1
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?