Question

In the nitrogen cycle, different forms of nitrogen move through all of Earth’s subsystems. Which step in the nitrogen cycle shows how nitrogen moves from the atmosphere to the geosphere?
A.
Decomposers in soil break down dead organisms and release atmospheric nitrogen.
B.
Nitrogen-fixing bacteria in the soil convert nitrogen from the air to make nitrates.
C.
Plants obtain nitrates through their roots in a process called assimilation.
D.
Animals get the nitrogen needed to grow by eating nitrogen-containing plants.

Answer 1

The correct answer is option B, that is, nitrogen-fixing bacteria in the soil convert nitrogen from the air to make nitrates.  

The nitrogen cycle is one of the major biogeographical cycles, it depicts the movement of nitrogen in different forms between the atmosphere, geosphere, and the biosphere. Identical to the carbon cycle, the nitrogen cycle comprises of different reservoirs of nitrogen and procedures by which those reservoirs interchange nitrogen.  

The atmospheric nitrogen cannot be used directly by plants and animals, it is the role of bacteria present in the soil known as nitrogen-fixing bacteria that converts the nitrogen from the air into nitrates, which is used by the plants.