What laboratory technique measures the physical and chemical characteristics of cells as they flow in a fluid stream through a beam of light, commonly used to analyze types of blood cells?

• A. Centrifugation
• B. Flow Cytometry
• C. PCR
• D. Microscopy

Answer: (B)

Flow cytometry is the technique that measures physical and chemical characteristics of cells as they flow in a fluid stream through a beam of light. As cells pass one by one through a laser, detectors capture forward scatter and side scatter to assess size and internal complexity, along with fluorescence from labeled antibodies that reveal specific markers. This combination lets you identify and quantify different blood cell types quickly—thousands of cells per second—and even sort them if needed. In contrast, centrifugation separates components by density without per‑cell characterization, PCR looks at DNA sequences, and microscopy provides images but isn’t as capable of high‑throughput multi‑parameter analysis.