Which biogeochemical cycle depends on bacteria to make the nutrient

Correct answer: A) Nitrogen cycle.
The biogeochemical cycle that depends on bacteria to make the nutrient usable by plants is the nitrogen cycle.

In the nitrogen cycle, atmospheric nitrogen (N2) is converted into forms that can be utilized by plants, such as ammonium (NH4+) and nitrate (NO3-), through a process called nitrogen fixation. This process is carried out by specialized nitrogen-fixing bacteria and archaea.

The key steps in the nitrogen cycle that involve bacteria include:
Nitrogen fixation: Certain bacteria, such as Rhizobium, can convert atmospheric nitrogen (N2) into ammonia (NH3) that can be absorbed by plants.
Nitrification: Nitrifying bacteria, such as Nitrosomonas and Nitrobacter, convert ammonia (NH3) into nitrites (NO2-) and then into nitrates (NO3-), which are readily available for plant uptake.
Denitrification: Denitrifying bacteria convert nitrates (NO3-) back into atmospheric nitrogen (N2), completing the cycle.
Without the crucial role of bacteria in the nitrogen cycle, plants would not be able to access the nitrogen they need for growth and development.

In contrast, the carbon cycle, phosphorus cycle, and water cycle do not primarily depend on bacteria to make the nutrients usable by plants.