Agroup of cells working together to preform a specific job is called

Tissue

Explanation: A group of cells doing the same job forms a tissue. A group of tissues working together forms an organ. and a group of organs doing the same job is called a system.  There are 11 major organ systems in the human body.

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.