What is the process of nitrogen fixation?

The process of nitrogen fixation is crucial for converting atmospheric nitrogen, which is largely unavailable to most organisms, into a usable form for plants, primarily in the form of ammonia or related compounds. This transformation is primarily facilitated by certain bacteria, including those that live in symbiosis with plants (like legumes), and free-living soil bacteria.

During nitrogen fixation, nitrogen gas (N₂) from the atmosphere is converted into ammonium (NH₄⁺) in a process that requires specific enzymes and energy, such as that derived from ATP. This ammonium can then be easily assimilated by plants to produce essential amino acids and nucleotides, which are fundamental building blocks for cellular processes.

Understanding this process highlights the role of nitrogen-fixing organisms in ecosystems, as they play a vital part in nitrogen cycling, ultimately enhancing soil fertility and promoting plant growth. By recognizing that nitrogen fixation directly relates to making nitrogen available for plant use, the significance of option B becomes clear.