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.
In addition, AGGRAND products contain nitrogen, phosphorus and potassium as primary macronutrients; and calcium, magnesium and sulfur as secondary macronutrients, all of which are the major drivers for plant growth and development: 1  Nitrogen is a component in all proteins that dictates the function of the plant cell.