The document outlines key concepts of cell theory, including that all living things are made of cells, cells are the basic unit of life, and all cells come from pre-existing cells. It also discusses evidence that supports cell theory, such as exceptions like connective tissue, and compares the relative sizes of various cellular and microscopic structures using SI units. Additionally, it explains that unicellular organisms carry out all life functions, that multicellular organisms show emergent properties and differentiate cells for specialized functions, and that stem cells can divide and differentiate along different pathways, with one example given of stem cells being therapeutically used in a bone marrow transplant.