<prompt> The common end product of catabolism of all pyrimidines is:Beta alanineUric acidUreaXanthine  <response>: 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. 