Basic Concepts and Clinical Applications of Flow Cytometry Practice
Exam
Question 1: What is the primary principle behind flow cytometry?
A: It uses centrifugation for cell separation.
B: It measures physical and chemical characteristics of cells in a fluid stream.
C: It relies on magnetic fields to separate cells.
D: It utilizes electrical impedance for cell counting.
Answer: B
Explanation: Flow cytometry measures the physical and chemical properties of cells as they flow
in a single file through a laser beam, allowing rapid multiparametric analysis.
Question 2: Which component of a flow cytometer is responsible for aligning cells in single
file?
A: Optical filters
B: Fluidics system
C: Detectors
D: Electronics system
Answer: B
Explanation: The fluidics system introduces the sample and uses hydrodynamic focusing to align
cells in a single file for analysis.
Question 3: What is the role of photomultiplier tubes (PMTs) in a flow cytometer?
A: To physically separate cells
B: To generate lasers
C: To detect and amplify light signals from fluorescent markers
D: To process digital data
Answer: C
Explanation: PMTs detect the faint light signals emitted by fluorescently labeled cells and
amplify these signals for analysis.
Question 4: Which light scatter parameter correlates with cell size in flow cytometry?
A: Side scatter (SSC)
B: Fluorescence
C: Forward scatter (FSC)
D: Compensation
Answer: C
Explanation: Forward scatter (FSC) is directly correlated with the size of the cell, providing
information about its volume.
Question 5: In flow cytometry, what does side scatter (SSC) primarily indicate?
A: Cell viability
B: Internal complexity or granularity
,C: Cell size
D: Fluorochrome intensity
Answer: B
Explanation: Side scatter (SSC) is related to the granularity or internal complexity of the cell,
such as the presence of granules or the complexity of internal structures.
Question 6: Which of the following is a common fluorochrome used in flow cytometry?
A: DAPI
B: Hematoxylin
C: Eosin
D: Crystal violet
Answer: A
Explanation: DAPI is a fluorescent stain that binds to DNA and is commonly used in flow
cytometry to identify and quantify nuclear material.
Question 7: What does the term “compensation” refer to in flow cytometry?
A: Adjusting cell concentration
B: Correcting for spectral overlap between different fluorochromes
C: Enhancing laser intensity
D: Balancing the fluidics system
Answer: B
Explanation: Compensation is the process of correcting for spectral overlap when the emission
spectra of different fluorochromes overlap.
Question 8: Which factor is crucial for successful hydrodynamic focusing?
A: High voltage supply
B: Sheath fluid dynamics
C: Optical alignment
D: Signal processing
Answer: B
Explanation: Sheath fluid dynamics are essential for hydrodynamic focusing, which aligns cells
in a single file within the fluid stream.
Question 9: What distinguishes flow cytometry from traditional microscopy?
A: Its inability to analyze multiple parameters simultaneously
B: Its capacity for rapid, high-throughput analysis of thousands of cells per second
C: Its reliance on static imaging
D: Its use of only fixed cells
Answer: B
Explanation: Flow cytometry can analyze thousands of cells per second and simultaneously
measure multiple parameters, unlike traditional microscopy.
Question 10: Which advancement significantly improved the sensitivity of flow cytometry?
A: The development of manual cell counting
B: The invention of photodiodes
C: The introduction of fluorescent labeling
,D: The use of magnetic separation
Answer: C
Explanation: The introduction of fluorescent labeling allowed specific cell components to be
tagged and measured, greatly enhancing the sensitivity and specificity of flow cytometric
analysis.
Question 11: Which historical development played a critical role in the evolution of flow
cytometry?
A: The discovery of centrifugation
B: The development of hydrodynamic focusing techniques
C: The invention of the electron microscope
D: The use of chemical stains in light microscopy
Answer: B
Explanation: Hydrodynamic focusing techniques were pivotal in developing flow cytometry,
allowing cells to be analyzed individually.
Question 12: Which laser type is most commonly used in flow cytometers for excitation?
A: Helium-neon laser
B: Diode laser
C: Gas discharge laser
D: Dye laser
Answer: B
Explanation: Diode lasers are commonly used in modern flow cytometers due to their stability,
size, and wavelength options.
Question 13: What does the optical filter in a flow cytometer do?
A: It amplifies the light signal.
B: It separates excitation and emission wavelengths.
C: It aligns cells in the sample stream.
D: It converts analog signals to digital.
Answer: B
Explanation: Optical filters are used to separate the excitation light from the emitted
fluorescence, ensuring accurate detection.
Question 14: How do beam splitters contribute to flow cytometry?
A: By combining multiple laser beams into one
B: By directing light to different detectors
C: By focusing the fluid stream
D: By enhancing electrical signals
Answer: B
Explanation: Beam splitters direct the emitted light into different detection channels, allowing
simultaneous measurement of multiple signals.
Question 15: What is the purpose of the electronics system in a flow cytometer?
A: To introduce cells into the fluid stream
B: To provide optical illumination
, C: To process signals and convert them into digital data
D: To stain the cells
Answer: C
Explanation: The electronics system processes and digitizes the signals generated by the
detectors, facilitating data analysis and visualization.
Question 16: Which factor directly affects the sensitivity of fluorescence detection in flow
cytometry?
A: Laser alignment
B: Photodetector efficiency
C: Sample viscosity
D: Cell size
Answer: B
Explanation: The efficiency of photodetectors, such as PMTs, directly influences the sensitivity
of fluorescence detection in flow cytometry.
Question 17: In sample preparation, why is fixation an important step?
A: It stains the cells.
B: It preserves cell structure and antigenicity.
C: It increases cell size.
D: It enhances light scattering.
Answer: B
Explanation: Fixation preserves cell morphology and antigenicity, which is essential for accurate
immunophenotyping and other analyses.
Question 18: What is the primary goal of cell staining protocols in flow cytometry?
A: To increase cell count
B: To selectively label cell markers for identification
C: To alter cell shape
D: To reduce sample volume
Answer: B
Explanation: Cell staining protocols use fluorochrome-conjugated antibodies to selectively label
cell surface or intracellular markers, aiding in cell identification.
Question 19: How is cell viability typically assessed in flow cytometry?
A: By measuring forward scatter only
B: Using viability dyes that distinguish live from dead cells
C: By altering laser intensity
D: Through compensation adjustments
Answer: B
Explanation: Viability dyes are used to stain dead cells differently from live cells, allowing for
accurate viability assessment during analysis.
Question 20: What is the significance of excluding doublets during flow cytometry data
acquisition?
A: It ensures that only single cells are analyzed for accurate results.
Exam
Question 1: What is the primary principle behind flow cytometry?
A: It uses centrifugation for cell separation.
B: It measures physical and chemical characteristics of cells in a fluid stream.
C: It relies on magnetic fields to separate cells.
D: It utilizes electrical impedance for cell counting.
Answer: B
Explanation: Flow cytometry measures the physical and chemical properties of cells as they flow
in a single file through a laser beam, allowing rapid multiparametric analysis.
Question 2: Which component of a flow cytometer is responsible for aligning cells in single
file?
A: Optical filters
B: Fluidics system
C: Detectors
D: Electronics system
Answer: B
Explanation: The fluidics system introduces the sample and uses hydrodynamic focusing to align
cells in a single file for analysis.
Question 3: What is the role of photomultiplier tubes (PMTs) in a flow cytometer?
A: To physically separate cells
B: To generate lasers
C: To detect and amplify light signals from fluorescent markers
D: To process digital data
Answer: C
Explanation: PMTs detect the faint light signals emitted by fluorescently labeled cells and
amplify these signals for analysis.
Question 4: Which light scatter parameter correlates with cell size in flow cytometry?
A: Side scatter (SSC)
B: Fluorescence
C: Forward scatter (FSC)
D: Compensation
Answer: C
Explanation: Forward scatter (FSC) is directly correlated with the size of the cell, providing
information about its volume.
Question 5: In flow cytometry, what does side scatter (SSC) primarily indicate?
A: Cell viability
B: Internal complexity or granularity
,C: Cell size
D: Fluorochrome intensity
Answer: B
Explanation: Side scatter (SSC) is related to the granularity or internal complexity of the cell,
such as the presence of granules or the complexity of internal structures.
Question 6: Which of the following is a common fluorochrome used in flow cytometry?
A: DAPI
B: Hematoxylin
C: Eosin
D: Crystal violet
Answer: A
Explanation: DAPI is a fluorescent stain that binds to DNA and is commonly used in flow
cytometry to identify and quantify nuclear material.
Question 7: What does the term “compensation” refer to in flow cytometry?
A: Adjusting cell concentration
B: Correcting for spectral overlap between different fluorochromes
C: Enhancing laser intensity
D: Balancing the fluidics system
Answer: B
Explanation: Compensation is the process of correcting for spectral overlap when the emission
spectra of different fluorochromes overlap.
Question 8: Which factor is crucial for successful hydrodynamic focusing?
A: High voltage supply
B: Sheath fluid dynamics
C: Optical alignment
D: Signal processing
Answer: B
Explanation: Sheath fluid dynamics are essential for hydrodynamic focusing, which aligns cells
in a single file within the fluid stream.
Question 9: What distinguishes flow cytometry from traditional microscopy?
A: Its inability to analyze multiple parameters simultaneously
B: Its capacity for rapid, high-throughput analysis of thousands of cells per second
C: Its reliance on static imaging
D: Its use of only fixed cells
Answer: B
Explanation: Flow cytometry can analyze thousands of cells per second and simultaneously
measure multiple parameters, unlike traditional microscopy.
Question 10: Which advancement significantly improved the sensitivity of flow cytometry?
A: The development of manual cell counting
B: The invention of photodiodes
C: The introduction of fluorescent labeling
,D: The use of magnetic separation
Answer: C
Explanation: The introduction of fluorescent labeling allowed specific cell components to be
tagged and measured, greatly enhancing the sensitivity and specificity of flow cytometric
analysis.
Question 11: Which historical development played a critical role in the evolution of flow
cytometry?
A: The discovery of centrifugation
B: The development of hydrodynamic focusing techniques
C: The invention of the electron microscope
D: The use of chemical stains in light microscopy
Answer: B
Explanation: Hydrodynamic focusing techniques were pivotal in developing flow cytometry,
allowing cells to be analyzed individually.
Question 12: Which laser type is most commonly used in flow cytometers for excitation?
A: Helium-neon laser
B: Diode laser
C: Gas discharge laser
D: Dye laser
Answer: B
Explanation: Diode lasers are commonly used in modern flow cytometers due to their stability,
size, and wavelength options.
Question 13: What does the optical filter in a flow cytometer do?
A: It amplifies the light signal.
B: It separates excitation and emission wavelengths.
C: It aligns cells in the sample stream.
D: It converts analog signals to digital.
Answer: B
Explanation: Optical filters are used to separate the excitation light from the emitted
fluorescence, ensuring accurate detection.
Question 14: How do beam splitters contribute to flow cytometry?
A: By combining multiple laser beams into one
B: By directing light to different detectors
C: By focusing the fluid stream
D: By enhancing electrical signals
Answer: B
Explanation: Beam splitters direct the emitted light into different detection channels, allowing
simultaneous measurement of multiple signals.
Question 15: What is the purpose of the electronics system in a flow cytometer?
A: To introduce cells into the fluid stream
B: To provide optical illumination
, C: To process signals and convert them into digital data
D: To stain the cells
Answer: C
Explanation: The electronics system processes and digitizes the signals generated by the
detectors, facilitating data analysis and visualization.
Question 16: Which factor directly affects the sensitivity of fluorescence detection in flow
cytometry?
A: Laser alignment
B: Photodetector efficiency
C: Sample viscosity
D: Cell size
Answer: B
Explanation: The efficiency of photodetectors, such as PMTs, directly influences the sensitivity
of fluorescence detection in flow cytometry.
Question 17: In sample preparation, why is fixation an important step?
A: It stains the cells.
B: It preserves cell structure and antigenicity.
C: It increases cell size.
D: It enhances light scattering.
Answer: B
Explanation: Fixation preserves cell morphology and antigenicity, which is essential for accurate
immunophenotyping and other analyses.
Question 18: What is the primary goal of cell staining protocols in flow cytometry?
A: To increase cell count
B: To selectively label cell markers for identification
C: To alter cell shape
D: To reduce sample volume
Answer: B
Explanation: Cell staining protocols use fluorochrome-conjugated antibodies to selectively label
cell surface or intracellular markers, aiding in cell identification.
Question 19: How is cell viability typically assessed in flow cytometry?
A: By measuring forward scatter only
B: Using viability dyes that distinguish live from dead cells
C: By altering laser intensity
D: Through compensation adjustments
Answer: B
Explanation: Viability dyes are used to stain dead cells differently from live cells, allowing for
accurate viability assessment during analysis.
Question 20: What is the significance of excluding doublets during flow cytometry data
acquisition?
A: It ensures that only single cells are analyzed for accurate results.
