A specialized cell means simply that it has a specific job. Therefore, specialized cells will contain more of the parts it needs to carry out the specialized task. A unicellular organism has only one cell which means that it has to carry out all functions of life in a single cell. Thus, it will have all the needed parts rather than specialized parts.
Nitrogen is a major component by which plants use sun energy to produce sugars from water and carbon dioxide. (It is also a major component of amino acids)
