Detailed Instructions: In this task you will be given a text passage from a trivia quiz. You should choose the category this question belongs to from these categories: History, Science, Social Science, Fine Arts, Literature. You can only choose one category, so if in doubt, please choose the closest match.
Q: nif regulon codes for enzymes central to this process, which may be inhibited by a shortage of alpha-ketoglutarate or excess glutamate. In some cyanobacteria, it is carried out in specialized thick-walled cells called heterocysts. Vanadium is sometimes used in an alternative co-factor to this process, but is not as common as FeMo-co, which contains homocitrate, an Fe7-S8 cube, and a (*) molybdenum center. The reductase involved in this process is irreversibly inactivated by oxygen, leading to conformational protection in free living aerobes like Azotobactor. This process is also carried out by bacteria including Rhizobium that grow in the root nodules of legumes. For 10 points, name this process which allows organisms to make use of a certain atmospheric gas by converting it to ammonia.
A:
Science