How is nitrogen returned to the atmosphere during the nitrogen cycle? a. It is returned to the atmosphere in a process called nitrogen fixation.
b. It is returned to the atmosphere through denitrification.
c. It is returned to the atmosphere through cellular respiration.
d. It is returned to the atmosphere through evapotranspiration.

Nitrogen is returned to the atmosphere during the nitrogen cycle through denitrification.

Therefore, nitrogen is returned to the atmosphere during the nitrogen cycle through denitrification.

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d. the weight of the book

during the process of dna replication, brdu can replace thymidine and incorporate into the newly synthesized dna, cell proliferation thus can be reflected in the extent of brdu incorporation.