Define Classification of functions of minerals?
 The varied functions of minerals can be grouped under four general physiologic roles viz.
-  Structural: They form an integral part of structures such as the bones/skeleton, blood etc.
-  Catalytic: Certain minerals are required as constituents of enzymes, co-enzymes in various metabolic pathways. 
-  Cellular: Some are necessary for membrane stability, as well as, inter and intra cellular transport mechanisms.
-  Others: They play an important role muscle contraction, nerve transmission etc.