1. Nitrogen Cycle N2

2. forms of nitrogen N2 – gas NH3 – ammonia (activity - smell it)
78% of our atmosphere is made of N2
NH3 – ammonia (activity - smell it)
contained in waste
NO2 – TOXIC gas
nitrite
NO3 – Good Stuff (fertilizer bag)
nitrate – in fertilizers for plants and algae; they absorb it and make proteins with it

4. Basic nitrogen cycle
The nitrogen cycle works this way: Plant and animal wastes decompose and add nitrogen to the soil. Bacteria in the soil convert these forms of nitrogen into forms plants use. Plants use the nitrogen in the soil to grow. People and animals eat the plants, then animal and plant residues return nitrogen to the soil again, completing the cycle.

5. Vocabulary nitrogen-fixation de-nitrification
process of how nitrogen (N2) turns into NO3
lightning, soil bacteria, bacteria in legume roots
de-nitrification
process of how NO3 get turned back in N2
excretion (removal of waste)
nitrogen is in form of NH3 – ammonia
kidney’s filter out NH3
legumes (high protein plants)
nuts, peas, alfalfa, soy, tofu, protein shakes (whey)

6. nitrogen in humans/animals
nitrogen is in all proteins
meat, eggs, nuts, dairy, legumes
flow of nitrogen
we eat proteins (steak)
we digest the steak
body assimilates (makes a part of) protein
NH3 (ammonia) is made and released
we excrete (poo) the leftovers