SCYM (ASCP) EXAM (2026) ACTUAL EXAM COMPREHENSIVE QUESTIONS AND
VERIFIED ACCURATE SOLUTION (DETAILED & ELABORATED) |GET IT 100%
ACCURATE!! 2026 TEST!!
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. - (Correct Answer)-Hydrodynamic Focusing
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 - (Correct Answer)-Hydordynamic focusing and sheath fluids
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. - (Correct Answer)-Sample Pressure and the Sheath Pressure
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). - (Correct
Answer)-differential pressure based flow cytometers
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. - (Correct Answer)-Generation of differential pressure (syringe pump, pressure
based)
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. - (Correct Answer)-Characterization of syringe-pump-driven
induced pressure
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 - (Correct Answer)-Optical Filters
, 2
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. - (Correct Answer)-Band Pass Optical Filter
wavelength above 650nM - (Correct Answer)-Longpass Filter
wavelength below 488nM - (Correct Answer)-Shortpass Filter
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. - (Correct Answer)-dichroics mirrors
filter that reduces or modifies the intensity of all wavelengths, or colors, of light equally, giving
no changes in hue of color rendition - (Correct Answer)-neutral density filter
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. - (Correct Answer)-
polarization filter
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. - (Correct Answer)-
light source
, 3
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. - (Correct Answer)-arc lamp laser
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). - (Correct Answer)-argon laser
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. - (Correct Answer)-solid state lasers
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. - (Correct Answer)-lenses
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 collimate that light so that all
rays propagate parallel to each other and can travel through the collection path without diverging.
- (Correct Answer)-What is the job of the lenses?
Dichroic filters (sometimes called beam splitters) are used in the flow cytometer at an angle
often of 45°. Short wavelength pass (SWP) filters transmit light below a given wavelength and
reflect light of longer wavelengths. Long wavelength pass (LWP) filters work in the reverse
fashion. Their important parameters are the wavelength for 50% transmission (the cut off for
LWP or the cut-on wavelength for SWP), the peak transmission and the slope at the cut-on or
cut-off wavelength. Their properties depend on the angle at which they are used. - (Correct
Answer)-Dichroic Filters
Optical fibers are used to deliver lasers to the interrogation point on some cytometers. This
strategy also provides a space-saving benefit in terms of where the lasers can be positions in the
instrument. However, a downside to this approach is that there can be significant power loss
between the laser output and the interrogation point as laser light travels through the fiber.
VERIFIED ACCURATE SOLUTION (DETAILED & ELABORATED) |GET IT 100%
ACCURATE!! 2026 TEST!!
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. - (Correct Answer)-Hydrodynamic Focusing
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 - (Correct Answer)-Hydordynamic focusing and sheath fluids
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. - (Correct Answer)-Sample Pressure and the Sheath Pressure
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). - (Correct
Answer)-differential pressure based flow cytometers
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. - (Correct Answer)-Generation of differential pressure (syringe pump, pressure
based)
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. - (Correct Answer)-Characterization of syringe-pump-driven
induced pressure
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 - (Correct Answer)-Optical Filters
, 2
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. - (Correct Answer)-Band Pass Optical Filter
wavelength above 650nM - (Correct Answer)-Longpass Filter
wavelength below 488nM - (Correct Answer)-Shortpass Filter
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. - (Correct Answer)-dichroics mirrors
filter that reduces or modifies the intensity of all wavelengths, or colors, of light equally, giving
no changes in hue of color rendition - (Correct Answer)-neutral density filter
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. - (Correct Answer)-
polarization filter
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. - (Correct Answer)-
light source
, 3
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. - (Correct Answer)-arc lamp laser
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). - (Correct Answer)-argon laser
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. - (Correct Answer)-solid state lasers
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. - (Correct Answer)-lenses
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 collimate that light so that all
rays propagate parallel to each other and can travel through the collection path without diverging.
- (Correct Answer)-What is the job of the lenses?
Dichroic filters (sometimes called beam splitters) are used in the flow cytometer at an angle
often of 45°. Short wavelength pass (SWP) filters transmit light below a given wavelength and
reflect light of longer wavelengths. Long wavelength pass (LWP) filters work in the reverse
fashion. Their important parameters are the wavelength for 50% transmission (the cut off for
LWP or the cut-on wavelength for SWP), the peak transmission and the slope at the cut-on or
cut-off wavelength. Their properties depend on the angle at which they are used. - (Correct
Answer)-Dichroic Filters
Optical fibers are used to deliver lasers to the interrogation point on some cytometers. This
strategy also provides a space-saving benefit in terms of where the lasers can be positions in the
instrument. However, a downside to this approach is that there can be significant power loss
between the laser output and the interrogation point as laser light travels through the fiber.
