Microbes that reduce N₂ to NH₃ engage in nitrogen ___________ .

Verified step by step guidance

1. Identify the process described: microbes converting nitrogen gas (N\_2) into ammonia (NH\_3).
2. Recall that this biochemical conversion is a key part of the nitrogen cycle, specifically the step where atmospheric nitrogen is made biologically available.
3. Understand that the term for this process is 'nitrogen fixation,' which involves the enzymatic reduction of N\_2 to NH\_3 by certain bacteria and archaea.
4. Recognize that nitrogen fixation is essential for incorporating nitrogen into organic molecules, supporting life on Earth.
5. Conclude that the blank in the sentence should be filled with 'fixation' to describe the activity of these microbes.

Key Concepts

Nitrogen Fixation

Nitrogen fixation is the biological process where certain microbes convert atmospheric nitrogen gas (N₂) into ammonia (NH₃), making nitrogen available in a form usable by plants and other organisms. This process is essential for incorporating inert nitrogen into the biosphere.

Role of Nitrogen-Fixing Microbes

Microbes such as certain bacteria and archaea possess the enzyme nitrogenase, which enables them to reduce N₂ to NH₃. These microbes can be free-living or symbiotic, like Rhizobium in legume root nodules, playing a critical role in soil fertility and ecosystem nitrogen cycling.

Nitrogen Cycle

The nitrogen cycle describes the movement of nitrogen through the environment, including fixation, nitrification, assimilation, ammonification, and denitrification. Nitrogen fixation is the first step, converting inert nitrogen gas into biologically accessible forms, sustaining life on Earth.