Final answer:
Chemically defined media contain only chemically known components, while chemically complex media contain extracts and digests of yeasts, meat, or plants with undetermined and variable amounts of individual components.
Step-by-step explanation:
Chemically defined media contain only chemically known components, while chemically complex media contain extracts and digests of yeasts, meat, or plants with undetermined and variable amounts of individual components. In chemically defined media, all individual chemical components are identified and the exact amounts of each are known, whereas in chemically complex media, the precise chemical composition of the medium is not known.