The common end product of catabolism of all pyrimidines is:

Answer is Urea, not beta alanine The end products of pyrimidine catabolism are NH3, CO2 & beta alanine (for Cytosine, Uracil) For Thymine, these are NH3, CO2 & beta amino iso butyrate. NH3 is the common end product, which can form Urea. Why beta alanine is not the answer - Because beta alanine is not common to all pyrimidines. Its only for Cytosine and Uracil. Option D - Xanthine is an intermediate of catabolism of purines.Xanthine gets conveed to uric acid by Xanthine Oxidase.Option B - Uric acid is the common end product of purine catabolism.However, in non-primate mammals, Allantoin is the end product of purine catabolism as an extra enzyme, Uricase is present.