Assuming no crossing over, what combinations of chromosomes are possible in the cells produced at the completion of Meiosis I?

The cells will contain either maternal or paternal chromosomal combination

Explanation:

If no crossing over occurs during Meiosis 1 then it greatly reduces the chances of better variations among the species. The resulting cells will contain the whole paternal or maternal genome of the parents that is result of less variant genetic combinations.

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.