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: -Bacteria in the soil or in plant roots convert nitrogen gas from the environment into solid nitrogen molecules that plants can utilize in the soil. The bacteria within the nodules convert free nitrogen to nitrates, which the host plant uses for growth.

Detailed explanation-3: -Nitrogen-fixing bacteria convert ammonia into nitrites and then nitrites into nitrates.

Detailed explanation-4: -Nitrogen is present as in the atmosphere which cannot be absorbed by plants or animals. Through nitrogen fixation, bacteria like Azotobacter, Rhizobium converts into ammonia which can be assimilated by plants. Hence, nitrogen fixation solves the major issue of non-assimilation of atmospheric nitrogen.

Detailed explanation-5: -Nitrogen-fixing bacteria are prokaryotic microorganisms that are capable of transforming nitrogen gas from the atmosphere into “fixed nitrogen” compounds, such as ammonia, that are usable by plants.