How are bacterial and fossil species defined

Bacterial: a microscopic, single-celled organisms that thrive in diverse environments.

fossil Species: the fossil species must be old relative to the time of origin of the extant clade (common ancestor).

Explanation:

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.