Question

why are bacteria needed in the nitrogen cycle?
○ other living things cannot use atmospheric nitrogen.
○ other living things cannot use the nitrogen in plants.
○ bacteria are the main nitrogen reservoir.
○ bacteria convert nitrogen gas into oxygen.

Explanation:

In the nitrogen - cycle, most living organisms cannot directly use atmospheric nitrogen which is in a relatively inert form. Nitrogen - fixing bacteria convert this atmospheric nitrogen into a form (such as ammonia) that other living things can use. The main nitrogen reservoir is the atmosphere, not bacteria. Bacteria do not convert nitrogen gas into oxygen. And other living things can use the nitrogen in plants after it has been processed through the nitrogen - cycle.

Answer:

Other living things cannot use atmospheric nitrogen.