Which of the following descriptions of techniques used to study transport and transport proteins is NOT true? A potentiometer can be used to measure electric potential of a live cell. Patch clamping is used to measure the electric potential and movement of ions across entire cell membranes but cannot distinguish individual ion channels. Frog oocytes are a useful cell type for the expression and study of channel proteins. The oocyte expression assay can be combined with patch clamping to study ion channel activity in isolation.