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.
Peas (Pisum sativum L.) contain two kinds of monodesmosidic, triterpene saponins, whose chemical structure is comparable to those of soybean saponins. Primarily, saponin B (soyasaponin I) has been reported to be the main component in green peas.