Considering the two answers given by Sam and Kenneth, which one do you think is correct?
Both Sam and Kenneth are correct.
Nitrogen is used by living organisms in protein synthesis. That is during the manufacturing of proteins. Proteins are made from amino-acids. First nitrogen is used to make amino acids and then these amino-acids together form proteins. So basically both the answers are correct, it's just that they have given it in a different way from one another. Proteins are required by living organisms to grow and repair their body parts.