Plants use inorganic sulfate to make important sulfur-containing compounds like cysteine. They reduce sulfate to sulfide and incorporate it into cysteine, which is a key molecule for making other sulfur-containing compounds. This process requires energy and happens in chloroplasts, with light playing a crucial role. The reduction of sulfate in plants is a major way sulfur-amino acids are produced for organisms that can't use sulfate directly. This process is similar to how plants assimilate nitrate.