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.
Because theyâre members of the legume family, beans can make use of nitrogen in their surrounding atmosphere, so itâs important not to be too generous with fertiliser. A balanced plant food like Thrive All Purpose Granular can be sprinkled beside the planting rows, or the growing plants can be fed with a high potash liquid plant food like Thrive Flower & Fruit.