what role does nitrogen play in plant  metabolism ?              1  mark 

 Nitrogen is one of the essential macro element required by plants. It is an important component of many structural, genetic and metabolic compounds in plant cells. Various functions of Nitrogen are:-

• It is a major component of green colour pigment-chlorophyll, the compound by which plants perform photosynthesis.
• It is also a major component of amino acids,which are further the building blocks of proteins. Some proteins act as structural units in plant cells while others act as enzymes. 
• Nitrogen is a component of energy-transfer compounds, such as ATP (adenosine triphosphate) .