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SCYM (ASCP) QUIZLET EXAM 2026
QUESTIONS AND CORRECT ANSWERS
Hydrodynamic Focusing - correct answer-Most modern flow cytometers
tightly position the sample for optical analysis via hydrodynamic focusing.
Here, a carrier fluid called the sheath fluid is used to position the sample of
cells into a single file for optical interrogation.
Hydordynamic focusing and sheath fluids - correct answer-The central
stream (sample stream) is focused and surrounded by the secondary
slower stream (sheath fluid). The shape and size of the flow cell is crucial
to hydrodynamic focusing, and traditionally the cell is nozzle shaped. ... In a
flow cytometer, the sheath fluid pressure is constant while the sample fluid
is adjusted
Sample Pressure and the Sheath Pressure - correct answer-The difference
between the sample pressure and the sheath pressure is the differential
pressure. This controls the width of the core stream and the total number of
cells passing the laser intercept.
differential pressure based flow cytometers - correct answer-Differential
pressure based flow cytometers currently dominate the market. These
systems have two pressure regulators. The first is at a constant pressure
that sets how fast the fluids runs at. The second is regulated by the
investigator (like on this LSR-II control panel).
,2 |Page
Generation of differential pressure (syringe pump, pressure based) -
correct answer-Low differential pressure allows the cells to move past the
interrogation point one at a time. .... One kind involves generating pressure
using a pump and regulator system ... Differential pressure based fluidic
system. ... peristaltic and/or syringe pumps to deliver the sample into the
instrument.
Characterization of syringe-pump-driven induced pressure - correct
answer-In syringe-pump-driven microfluidic systems, pressure fluctuations
are observed in an elastic microchannel. The syringe pump is driven by an
electrical stepper motor, from which mechanical oscillations are expected
to generate flow-rate fluctuations and in turn leads to the pressure
fluctuations in the channel flow.
Optical Filters - correct answer-Filters are pieces of glass coated on both
sides that allow light of a certain collection, or band, of wavelengths to pass
through while absorbing or interfering with photons of other wavelengths.
These come in bandpass, longpass, and shortpass flavors
Band Pass Optical Filter - correct answer-A filter that allows light between a
set wavelength to pass through and reflects light above and below the set
wavelength. For example, a bandpass filter with a wavelength of 550/40nm
would allow light between 530nm and 570nm to pass through, but reflect
light below 530nm and above 570nm.
Longpass Filter - correct answer-wavelength above 650nM
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Shortpass Filter - correct answer-wavelength below 488nM
dichroics mirrors - correct answer-Dichroic mirrors can block light by
phased reflection allowing certain light to pass through and interfering with
other wavelengths. For example, a 500LP dichroic mirror would transmit
light above 500 nm and reflect the light below 500 nm in a different
direction. A 525SP dichroic mirror would transmit all light below 525 nm
and reflect all light above 525 nm in a different direction. These dichroic
mirrors are critical in the directing and capturing of light by the detectors.
neutral density filter - correct answer-filter that reduces or modifies the
intensity of all wavelengths, or colors, of light equally, giving no changes in
hue of color rendition
polarization filter - correct answer-Polarization of scatter and fluorescence
signals in flow cytometry. ... depending on the light source(s), the optical
layout, and the types of mirrors and filters used.
light source - correct answer-The light source can be a laser, an arc lamp
or even an LED. Today, the majority of instruments use a laser. Lasers
illuminate the stream with coherent, focused light of specific wavelength
(energy) and power. This illumination facilitates the generation of
fluorescence signals from cells labeled with fluorophores and light scatter
signals from redirected laser light.
, 4 |Page
arc lamp laser - correct answer-Arc lamps need optical filters to select the
appropriate wavelength. They do not give the sensitivity needed to observe
weak fluorescence but offer a cheaper alternative for observing strong
fluorescences, for example, in DNA analysis.
argon laser - correct answer-Air-cooled argon-ion laser producing blue light
at 488 nm. This wavelength is convenient for the excitation of fluorescein,
the first immunofluorescent label to be used. Other air-cooled lasers in
general use include He-Ne (633 nm) and He-CD (325 nm).
solid state lasers - correct answer-Solid state lasers producing light at 355,
405, 488, 530, 594, 635 and 780 nm are available. Most solid state lasers
produce between 10 and 25 mW. There is at least one diode laser giving
200 mW at 488 nm.
lenses - correct answer-As the lasers interact with particles and cells at the
observation point or the interrogation point, scattered and fluorescence light
is generated. In order to measure this light, the cytometer needs to collect
as much of it as possible.
What is the job of the lenses? - correct answer-The optical collection
system of a cytometer must accomplish two goals. First, it must gather as
much light as possible from the interrogation point. Second, it must
SCYM (ASCP) QUIZLET EXAM 2026
QUESTIONS AND CORRECT ANSWERS
Hydrodynamic Focusing - correct answer-Most modern flow cytometers
tightly position the sample for optical analysis via hydrodynamic focusing.
Here, a carrier fluid called the sheath fluid is used to position the sample of
cells into a single file for optical interrogation.
Hydordynamic focusing and sheath fluids - correct answer-The central
stream (sample stream) is focused and surrounded by the secondary
slower stream (sheath fluid). The shape and size of the flow cell is crucial
to hydrodynamic focusing, and traditionally the cell is nozzle shaped. ... In a
flow cytometer, the sheath fluid pressure is constant while the sample fluid
is adjusted
Sample Pressure and the Sheath Pressure - correct answer-The difference
between the sample pressure and the sheath pressure is the differential
pressure. This controls the width of the core stream and the total number of
cells passing the laser intercept.
differential pressure based flow cytometers - correct answer-Differential
pressure based flow cytometers currently dominate the market. These
systems have two pressure regulators. The first is at a constant pressure
that sets how fast the fluids runs at. The second is regulated by the
investigator (like on this LSR-II control panel).
,2 |Page
Generation of differential pressure (syringe pump, pressure based) -
correct answer-Low differential pressure allows the cells to move past the
interrogation point one at a time. .... One kind involves generating pressure
using a pump and regulator system ... Differential pressure based fluidic
system. ... peristaltic and/or syringe pumps to deliver the sample into the
instrument.
Characterization of syringe-pump-driven induced pressure - correct
answer-In syringe-pump-driven microfluidic systems, pressure fluctuations
are observed in an elastic microchannel. The syringe pump is driven by an
electrical stepper motor, from which mechanical oscillations are expected
to generate flow-rate fluctuations and in turn leads to the pressure
fluctuations in the channel flow.
Optical Filters - correct answer-Filters are pieces of glass coated on both
sides that allow light of a certain collection, or band, of wavelengths to pass
through while absorbing or interfering with photons of other wavelengths.
These come in bandpass, longpass, and shortpass flavors
Band Pass Optical Filter - correct answer-A filter that allows light between a
set wavelength to pass through and reflects light above and below the set
wavelength. For example, a bandpass filter with a wavelength of 550/40nm
would allow light between 530nm and 570nm to pass through, but reflect
light below 530nm and above 570nm.
Longpass Filter - correct answer-wavelength above 650nM
,3 |Page
Shortpass Filter - correct answer-wavelength below 488nM
dichroics mirrors - correct answer-Dichroic mirrors can block light by
phased reflection allowing certain light to pass through and interfering with
other wavelengths. For example, a 500LP dichroic mirror would transmit
light above 500 nm and reflect the light below 500 nm in a different
direction. A 525SP dichroic mirror would transmit all light below 525 nm
and reflect all light above 525 nm in a different direction. These dichroic
mirrors are critical in the directing and capturing of light by the detectors.
neutral density filter - correct answer-filter that reduces or modifies the
intensity of all wavelengths, or colors, of light equally, giving no changes in
hue of color rendition
polarization filter - correct answer-Polarization of scatter and fluorescence
signals in flow cytometry. ... depending on the light source(s), the optical
layout, and the types of mirrors and filters used.
light source - correct answer-The light source can be a laser, an arc lamp
or even an LED. Today, the majority of instruments use a laser. Lasers
illuminate the stream with coherent, focused light of specific wavelength
(energy) and power. This illumination facilitates the generation of
fluorescence signals from cells labeled with fluorophores and light scatter
signals from redirected laser light.
, 4 |Page
arc lamp laser - correct answer-Arc lamps need optical filters to select the
appropriate wavelength. They do not give the sensitivity needed to observe
weak fluorescence but offer a cheaper alternative for observing strong
fluorescences, for example, in DNA analysis.
argon laser - correct answer-Air-cooled argon-ion laser producing blue light
at 488 nm. This wavelength is convenient for the excitation of fluorescein,
the first immunofluorescent label to be used. Other air-cooled lasers in
general use include He-Ne (633 nm) and He-CD (325 nm).
solid state lasers - correct answer-Solid state lasers producing light at 355,
405, 488, 530, 594, 635 and 780 nm are available. Most solid state lasers
produce between 10 and 25 mW. There is at least one diode laser giving
200 mW at 488 nm.
lenses - correct answer-As the lasers interact with particles and cells at the
observation point or the interrogation point, scattered and fluorescence light
is generated. In order to measure this light, the cytometer needs to collect
as much of it as possible.
What is the job of the lenses? - correct answer-The optical collection
system of a cytometer must accomplish two goals. First, it must gather as
much light as possible from the interrogation point. Second, it must
