what type of microscope would a biologist use to study sub-cellular structures?

A biologist would use an electron microscope to study sub-cellular structures. Electron microscopes have much higher magnifying power and resolution than light microscopes, enabling visualization of subcellular organelles and macromolecular complexes in great detail, down to nanometer or even atomic scales. Specifically, transmission electron microscopy (TEM) is commonly used to observe the internal structure of cells by passing electrons through thin sections, revealing organelles and molecular structures. Additionally, advanced light microscopy techniques such as super-resolution microscopy (e.g., Single-Molecule Localization Microscopy, SMLM) can also be used to study subcellular structures beyond the diffraction limit of light, but electron microscopy remains the primary tool for ultrastructural analysis.