The nitrogen cycle is carried out primarily by
A.humans
B.autotrophs
C.bacteria
D.fungi
http://www.ducksters.com/science/ecosystems/nitrogen_cycle.php
The nitrogen cycle is primarily carried out by C. bacteria.
To find the answer to this question, you can start by understanding the process of the nitrogen cycle. The nitrogen cycle is the movement of nitrogen in different forms through different parts of the environment. It is an important process that is crucial for the growth and survival of living organisms.
Firstly, nitrogen gas (N₂) makes up about 78% of Earth's atmosphere, but most organisms can't use nitrogen in this form. Therefore, the process starts with nitrogen fixation, where certain bacteria convert atmospheric nitrogen gas into a usable form called ammonia (NH₃). This process is known as nitrogen fixation.
The next step is nitrification, where other bacteria convert ammonia (NH₃) into nitrite (NO₂⁻) and then into nitrate (NO₃⁻). This conversion is done by different species of nitrifying bacteria.
Once the nitrogen is in the form of nitrate, it can be taken up by plants, which are autotrophs. Autotrophs use nitrate and incorporate it into their tissues to build proteins and other nitrogen-containing compounds.
After plants and other autotrophs have taken up the nitrogen, it can then be passed along the food chain to other organisms. When these organisms die or produce waste, the nitrogen is released back into the environment in the form of organic matter or ammonium (NH₄⁺). This step is called ammonification.
Finally, denitrification occurs, where other bacteria convert the ammonium (NH₄⁺) back into atmospheric nitrogen gas (N₂), completing the nitrogen cycle.
In this context, the primary role in carrying out the nitrogen cycle is played by bacteria. They are responsible for nitrogen fixation, nitrification, ammonification, and denitrification, which are key processes in the nitrogen cycle.