Experiments with Azotobacter Chroococcum Have Led to the Observation That

Multiple Choice

Experiments with Azotobacter chroococcum have led to the observation that

A) nitrogenase reduces nitrogen to ammonia.
B) acetylene may be reduced by nitrogenase.
C) nitrogenase may contain molybdenum and iron.
D) two alternative nitrogenases can be made under certain growth conditions.