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 other nitrogen fixing agents are found in the roots of leguminous plants such as beans, peas and clover. The roots of these plants have nodules which contain the bacteria that convert the atmospheric nitrogen into compounds which plants can use.mmonia is one of the more common modified forms of nitrogen that plants absorb from the soil. The process by which atmospheric nitrogen is converted into compounds such as ammonia that plants can readily use is known as nitrogen fixation.