Question

$N_2$ fixation is?
A) $N_2$ $\rightarrow$ $NH_3$
B) $NO_3$ $\rightarrow$ $NO_2$
C) $N_2$ $\rightarrow$ Amino acid
D) Both (1) and (2)

Answer 1

Hint: Nitrogen Cycle is a biogeochemical cycle through which nitrogen is converted over into numerous forms, consecutively passing from the atmosphere to the soil to organisms and back into the environment/atmosphere. It includes a few cycles, for example, nitrogen fixation, nitrification, denitrification and decay.

Complete answer:
 Nitrogen cycles incorporate fixation, ammonification, nitrification, and denitrification. Most of Earth's air (78%) is nitrogen, making it the largest source of nitrogen. Atmospheric nitrogen has restricted accessibility for natural use, prompting a scarcity of usable nitrogen in numerous types of ecosystems.

Nitrogen is available in the atmosphere in a wide variety of chemical forms and compound structures including organic nitrogen, ammonium, nitrite, nitrate, nitrous oxide, nitric oxide or inorganic nitrogen gas. Natural nitrogen might be in the form of a living organism, humus or in the intermediate products of organic matter decomposition. The processes in the nitrogen cycle is to convert nitrogen starting with one form then onto the next.

A lot of these processes are done by the microbes, either in their efforts to collect energy or to accumulate nitrogen in a form needed for their development and growth. For instance, the nitrogenous wastes in animal urine are broken down by nitrifying microorganisms in the soil to be utilized by plants.

Nitrogen fixation is a cycle by which nitrogen in the Earth's climate is converted over into ammonia. After nitrogen has been fixed, other microscopic organisms convert it into nitrate, in a cycle known as nitrification. In the initial step of this cycle, Nitrosomonas convert ammonia into nitrite, and in the second step, nitrite is changed over into nitrate, by Nitrobacter. This nitrate is then taken up by the plants.

Hence, the correct answer is option (A)

Note: Bacteria like Azotobacter, Rhizobium have the nitrogenase enzyme that combines gaseous nitrogen with hydrogen to deliver ammonia, which is changed over by the microorganisms into other organic compounds. Most organic nitrogen fixation happens by the movement of Mo-nitrogenase, found in a wide variety of microorganisms and some Archaea.