Western Governors University (WGU) BIO1010 C190 Introduction to Biology Practice Exam

Nitrogen fixation is primarily driven by bacteria, specifically certain types of prokaryotes known as diazotrophs. These bacteria possess the unique ability to convert atmospheric nitrogen (N₂), which plants and animals cannot utilize, into ammonia (NH₃) or related compounds that can be assimilated by living organisms. This process is crucial in the nitrogen cycle because it makes nitrogen available in a form that plants can take up and use to synthesize proteins and other important biomolecules.

Many of the bacteria involved in nitrogen fixation are found in the soil, while others form symbiotic relationships with the roots of specific plants, particularly legumes such as soybeans and clover. Within these symbiotic relationships, the plants provide carbohydrates and other organic compounds to the bacteria, while the bacteria supply nitrogenous compounds to the plants, promoting their growth and health.

This underscores the importance of bacteria in maintaining ecological balance and contributing to soil fertility. Other organisms, like fungi, plants, and insects, may play roles in the ecosystem or nitrogen cycle, but they do not directly carry out the process of nitrogen fixation as the specialized bacteria do.