Which term describes the migration of large ions in electrophoresis?

• A. Iontophoresis
• B. Endosmosis
• C. Zone electrophoresis
• D. Isoelectric focusing

Answer: (C)

Migration of large ions in electrophoresis is described as zone electrophoresis. In this approach, the sample is applied as a narrow zone and, under an electric field, ions move and form distinct moving zones that separate components by their size and charge. This zonal pattern is what the technique emphasizes, distinguishing it from other processes: iontophoresis drives ions into tissues; endosmosis refers to bulk solvent flow under the field; and isoelectric focusing separates by pH gradient at the isoelectric point rather than by simple size-driven migration. Thus zone electrophoresis best captures the migration behavior of large ions in electrophoresis.