Carboxyl groups have an electronegative oxygen atom double bonded to a carbon atom. This carbon-oxygen bond is very polar and the fact that its a double bond increases the polarity of the bond.
PEA agar, also referred to as Phenylethyl Alcohol Agar is a medium  used by microbiologists to grow microorganisms. The ingredient that  supplies nitrogen is casein. Making the world better, one answer at a time.
The numbers on the package indicate the strength of the main ingredients. The first number represents the amount of nitrogen, the second phosphorus and the third potassium. As with most lawn fertilizers, nitrogen is the most abundant ingredient of Scotts Turf Builder, which is a 32-0-4 fertilizer. This dry, granulated fertilizer remains viable in storage indefinitely.