The document summarizes key information about terpenes, alkaloids, vitamins, and their classification and functions. Terpenes are composed of isoprene units and include monoterpenes, sesquiterpenes, diterpenes, triterpenes, and tetraterpenes. Alkaloids have nitrogen and are derived from plants, functioning in chemical defense. Vitamins are classified as water-soluble or fat-soluble, and each has a specific biochemical function as a coenzyme or precursor.