Plants need nitrogen to grow and fight off pests. They can't use nitrogen from the air directly, so they take it in as nitrate, ammonium, or other forms. Bacteria in some plants help convert air nitrogen to a usable form. The type of nitrogen a plant gets affects its growth and ability to fight diseases. Not having enough nitrogen can lead to stunted growth and less food production. Enzymes like nitrate reductase and glutamine synthase help plants use nitrogen effectively. Understanding how these enzymes work is crucial for plant health and crop yield.