Practice question

Scanning Electron Microscopy visualizes surface topography by scanning a focused electron beam across specimen coated with conductive metal. Secondary electrons ejected from surface, with energy sensitive to tilt and composition, produce detailed three-dimensional appearance with great depth of field. Unlike transmission methods requiring ultrathin sections for internal ultrastructure, SEM preserves whole cells, tissues, pollen, and microorganisms after fixation and dehydration. Magnification ranges enable visualization from millimeters to few nanometers, making SEM ideal for examining microvilli, bacterial biofilms, and surface architecture in developmental biology.