Give scientific reasons:
$(1)$ Leguminous plants are rich in protein.

(N/A) Nodules are present on the roots of leguminous plants. Symbiotic bacteria,$Rhizobium$,reside within these nodules. These bacteria fix atmospheric nitrogen into ammonia. Plants synthesize amino acids using this ammonia. Many such amino acids connect with each other via peptide bonds to form polypeptides,which ultimately form proteins. Thus,leguminous plants possess protein in abundance.