1) Nitrogen is essential for organisms but it exists mainly as unusable N2 gas in the atmosphere. It must be converted to biologically available forms through the nitrogen cycle. 2) The nitrogen cycle describes the movement of nitrogen between the atmosphere, biosphere, and lithosphere through processes like nitrogen fixation, uptake, mineralization, nitrification, and denitrification. 3) Nitrogen fixation converts atmospheric N2 to ammonium through processes like nitrogen-fixing bacteria in legume roots and the use of synthetic nitrogen fertilizers.

1. The Nitrogen Cycle 2 ~ Sampaguita Group 6 ۝ Celz Alejandro ۝ ۝ Jade Castro ۝ ۝ Josh Quinto ۝ ۝ Cheska Regalado ۝ ۝ Geo Robeniol ۝

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