BIOL 3362 - EXAM 1 STUDY GUIDE.

BIOL 3362 - EXAM 1 STUDY GUIDE/BIOL 3362 - EXAM 1 STUDY GUIDE. Nitrate assimilation - The reduction of NO3- to NH4+ in green plants, various fungi, and certain bacteria in a 2 step metabolic pathway. Conversion of nitrate to ammonia. Nitrogen Fixation - formation of NH4+ from N2 gas. Exclusively a prokaryotic process (but bacteria in symbiotic association with certain green plants can also carry out process) conversion of N2 to ammonia - occurs only in bacteria that are able to access nitrogen from the atmosphere. Nitrification - bacteria take reduced nitrogen, as ammonia, oxidize it to form nitrite and then to nitrate and use the energy released during the process for growth. Makes nitrogen more readily available for plants. Nitrate is more soluble than ammonia and plants absorb it more quickly.