Question

1. where is nitrogen found in the abiotic environment? 11. where is nitrogen found in the biotic environment? 12. how does nitrogen get into the atmosphere? 13. how does nitrogen get into living organisms?

Explanation:

1. Nitrogen in the abiotic environment is mainly in the atmosphere as nitrogen - gas ($N_2$), also in soil and water as nitrate ($NO_3^-$), nitrite ($NO_2^-$) and ammonium ($NH_4^+$) compounds from weathering of rocks and industrial processes.
2. In the biotic environment, nitrogen is found in proteins, nucleic acids (DNA and RNA) and other nitrogen - containing biomolecules in plants, animals and microorganisms.
3. Nitrogen gets into the atmosphere mainly through denitrification by bacteria in soil and water, which convert nitrate ($NO_3^-$) into nitrogen gas ($N_2$) and nitrous oxide ($N_2O$). Also, volcanic eruptions and industrial activities release nitrogen - containing gases.
4. Nitrogen gets into living organisms through nitrogen fixation. Certain bacteria (e.g., Rhizobium in root nodules of legumes) convert atmospheric nitrogen ($N_2$) into ammonia ($NH_3$), which can be used by plants to make proteins and other nitrogen - containing compounds. Animals then obtain nitrogen by eating plants or other animals.

Answer:

1. In the atmosphere as $N_2$, in soil and water as $NO_3^-$, $NO_2^-$, $NH_4^+$.
2. In proteins, nucleic acids and other biomolecules in plants, animals and microorganisms.
3. Through denitrification by bacteria, volcanic eruptions and industrial activities.
4. Through nitrogen - fixation by certain bacteria, then plants use it and animals eat plants/other animals.