SCYM Instrument Operation 2

Question 1

What is the primary purpose of the sheath fluid in a flow cytometer?

Accepted Answer

To hydrodynamically focus cells into a single-file stream

Answer

Sheath fluid creates laminar flow that hydrodynamically focuses the sample stream so cells pass through the laser interrogation point one at a time.

Question 2

Which parameter is used to distinguish doublets from single cells during flow cytometric analysis?

Accepted Answer

FSC height vs FSC area (or width)

Answer

Doublet discrimination is performed by comparing FSC-H (height) vs FSC-A (area); doublets produce disproportionately higher area relative to height.

Question 3

When performing daily QC on a flow cytometer using fluorescent beads, a sudden rightward shift in bead peak CV is most likely caused by:

Accepted Answer

Laser power fluctuation

Answer

Laser power instability causes variable fluorescence excitation, broadening the bead peak and increasing CV.

Question 4

In a spectral flow cytometer, unmixing algorithms require which reference material?

Accepted Answer

Single-color controls (single-stained references) for each fluorochrome

Answer

Spectral unmixing requires single-color reference spectra for each fluorochrome to mathematically separate overlapping emission signals across detectors.

Question 5

The time delay setting in a cell sorter is used to:

Accepted Answer

Synchronize the deflection charge with the droplet containing the target cell

Answer

The time delay (sort delay) accounts for the transit time from the laser interrogation point to the droplet break-off point so the correct droplet is charged.

(SCYM) Specialist in Cytometry Practice Test

(SCYM) Specialist in Cytometry Practice Test

SCYM Instrument Operation 2