Final answer:
Bacteria are essential to the nitrogen cycle because they convert atmospheric nitrogen into forms usable by plants and other organisms. The phosphorus cycle, unlike the nitrogen cycle, does not involve a gaseous phase and is often the limiting factor in ecosystems for growth due to its scarcity.
Step-by-step explanation:
Bacteria play a crucial role in the nitrogen cycle by fixing atmospheric nitrogen, which is essential for all life forms. Unlike nitrogen, phosphorus does not have a gaseous phase and moves slowly through the phosphorus cycle. The scarcity of phosphorus can limit biological nitrogen fixation, but bacteria facilitate the conversion of nitrogen into a form that is usable by plants and other organisms.
The phosphorus cycle differs from other biogeochemical cycles since it lacks a gaseous phase and is mostly restricted to soil and water transformations. Phosphorus tends to be the limiting nutrient in many ecosystems, required for critical biological molecules like nucleic acids and ATP.
Prokaryotic organisms, such as bacteria, are indispensable for biological nitrogen fixation, converting inert atmospheric nitrogen into ammonia, which is then further converted into usable forms for plants. Ultimately, this nitrogen feeds into the ecosystem, supporting a wide range of life forms.