Methanogens are able to live in an xyz environment
Extremely hot
Extremely acidic
anaerobic
Extremely salty

the nitrogen cycle provides nitrogen to the ecosystem from the atmosphere, ground and oceans. nitrogen is an important component of complex molecules such as amino acids and nucleotides, which lead to the creation of proteins and dna, the building blocks of all life. plants absorb nitrogen in the form of ammonium, nitrate ion and, on rare occasions, as amino acids. animals receive nitrogen necessary for biological processes from feeding on living or dead organic matter.

for a different answer set the answer would be because the oxygen in the water had depleted (apex)

its b. greenhouse gasses trap uv rays for heat so that the plants stay alive.