Use the image below:
What is happening in this model? (just the answer, no need to restate)

In the middle of the model is the stem cell, which can turn into the other cells shown.

Explanation:

did u get the answer? /? ? / me

explanation:

b,bacteria convert nitrates

into nitrogen gas.

d,plants and animals take in

and use nitrogen compounds.

e,bacteria break down waste    

products and return nitrogen  

to the soil.

a,bacteria convert atmospheric

nitrogen to ammonia.

c,bacteria convert ammonia

to nitrites and nitrates.