Question

which letter demonstrates nitrogen fixation (biological) in the nitrogen cycle? a a b e c g d f

Explanation:

Biological nitrogen - fixation is the process by which nitrogen - fixing bacteria convert atmospheric nitrogen ($N_2$) into ammonia ($NH_3$). In the nitrogen cycle diagram, this is typically shown as bacteria in the soil interacting with the atmosphere. Usually, these bacteria are associated with plant roots or free - living in the soil. Based on common nitrogen - cycle diagrams, the area representing the conversion of atmospheric nitrogen to a form usable by plants (ammonia) is often depicted as the starting point of the cycle related to biological activity.

Answer:

A. A