Which statement forms part of cell theory?

All living things are made up of cells.

The cell theory is a widely accepted principle of biology. Scientists that contributed to the cell theory include; Theodor Schwann, Matthias Schleiden, and Rudolph Virchow.

The cell theory states that;

All living organisms are made up of cells and they may be unicellular or multicellular.

The cell is the basic structural and functional unit of life.

Cells arise from pre-existing cells.  

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.