??? ??? ??? abiotic a nonliving factor or element (light,water,heat,rock,energy,mineral) ??? ??? ??? acid deposition precipitatation with a pH less than 5.6 that forms in the atmosphere when certain pollutants mix with water vapor ??? ??? ??? alllele any of a set of possible forms of a gene ??? ??? ??? biochemical conversion the changing of organic matter into other chemical forms ??? ??? ??? biol