Do all cells have the same identical DNA?

No.

Explanation: We are all unique. If all our cells had the same DNA we would all be the same. Also specific calls in one’s body do certain things and if they all had the same DNA your body wouldn’t properly function.

step 1: nitrogen fixation- conversion of atmospheric no₂ into forms useful to plants by lightning, bacteria, and cyanobacteria.

step 2: nitrification-process of converting ammonia to nitrite or nitrate.

step 3: assimilation-plant roots absorb new form of nitrogen.

step 4: ammonification-conversion of organic nitrogen to ammonia by bacteria involved in decomposition.

step 5: denitrification-bacteria turns the decomposed matter back into n₂o, which is released into atmosphere; repeat cycle.