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.
And fertilizer is actually not food for your lawn, it is actually the building blocks that the lawn plants use to put their parts together. And the basic ingredients are nitrogen, phosphorus and potassium. And when you break down, the nitrogen, think green. Nitrogen is for the green parts, the blades of the plants.