AP BIOLOGY

Detailed explanation-1: -Nitrogen-fixing bacteria in the soil and within the root nodules of some plants convert nitrogen gas in the atmosphere to ammonia. Nitrifying bacteria convert ammonia to nitrites or nitrates. Ammonia, nitrites, and nitrates are all fixed nitrogen and can be absorbed by plants.

Detailed explanation-2: -Biological nitrogen fixation (BNF), discovered by Beijerinck in 1901 (Beijerinck 1901), is carried out by a specialized group of prokaryotes. These organisms utilize the enzyme nitrogenase to catalyze the conversion of atmospheric nitrogen (N2) to ammonia (NH3).

Detailed explanation-3: -Bacteria that convert atmospheric nitrogen into nitrogen compounds like ammonia are called nitrogen-fixing bacteria. These bacteria make nitrogen available for the plants. These are of 2 types, symbiotic nitrogen-fixing bacteria like Rhizobium and non-symbiotic nitrogen-fixing bacteria like Azotobacter.

Detailed explanation-4: -Nitrifying bacteria in the soil convert ammonia into nitrite (NO2-) and then into nitrate (NO3-). This process is called nitrification. Compounds such as nitrate, nitrite, ammonia and ammonium can be taken up from soils by plants and then used in the formation of plant and animal proteins.

Detailed explanation-5: -The bacteria that we are talking about are called nitrosomonas and nitrobacter. Nitrobacter turns nitrites into nitrates; nitrosomonas transform ammonia to nitrites.