Answer:
The nitrogen cycle could not exist without first nitrogen. The cycle is about this specific element which goes to show that if this element is not present then, there will not be any nitrogen cycle. Also, an important factor for the cycle is the presence of the bacteria and other microorganism which are needed for the fixation.
The oldest layers are on the bottom, and the youngest layers are on the top.
I think it should be producers. i apologize if this is wrong, but that’s my best guess. hope this helps you!
