SCYM Flow Cytometry Principles 3

Question 1

Which type of laser is most commonly used in clinical flow cytometers for exciting FITC and PE simultaneously?

Accepted Answer

Blue argon-ion or solid-state laser (488 nm)

Answer

The 488 nm blue laser efficiently excites both FITC and PE, which is why they are among the most widely used fluorochromes in clinical cytometry.

Question 2

What is the Stokes shift in the context of fluorescence?

Accepted Answer

The difference in wavelength between the excitation and emission peaks of a fluorochrome

Answer

Stokes shift refers to the longer emission wavelength compared to the excitation wavelength, which allows emitted light to be separated from excitation light.

Question 3

In a flow cytometer, bandpass filters are used to:

Accepted Answer

Transmit only a specific range of wavelengths to the appropriate detector

Answer

Bandpass filters allow only a defined range of wavelengths to pass through to the detector, enabling detection of specific fluorochrome emissions.

Question 4

What is 'doublet discrimination' in flow cytometry?

Accepted Answer

A gating strategy to exclude cell aggregates from analysis

Answer

Doublet discrimination uses pulse width or area versus height plots to gate out cell aggregates that could be mistaken for single large cells.

Question 5

Which PMT (photomultiplier tube) voltage setting principle is correct?

Accepted Answer

Higher voltage increases signal amplification and sensitivity

Answer

Increasing PMT voltage amplifies the electrical signal from detected photons, improving sensitivity for dim populations but also amplifying noise.

(SCYM) Specialist in Cytometry Practice Test

(SCYM) Specialist in Cytometry Practice Test

SCYM Flow Cytometry Principles 3