Phosphorous is a very important molecule for both plants and animals.
Phosphorus is present in bones - bound as insoluble mineral hydoxylpatite. It controls protein activity (especially enzymes) and is a critical component of high energy molecules. It also forms the backbone of DNA and RNA. Almost all organic phosphorus present in biological systems is derived from phosphoric acid and phosphate. The key property of ionisation and protonation behaviour makes the phosphate molecules highly soluble and able to react as they form esters.