Multiple Choice Question on Metabolism and Disposal of Urea, Creatinine, and Uric Acid 1) The urea molecule consists of two Nitrogens and one carbon atom. The first nitrogen atom is derived from the free ammonium ion and the second is from an amino acid. The amino acid that donates the second amino group for the formation of urea is ................................ a) Arginine b) Aspartate c) Glutamate d) Ornithine 2) The free ammonium group (NH4+) is derived from the following processes : a) Oxidative deamination of Glutamine catalyzed by enzyme glutamate dehydrogenase b) Deamidation of histidine catalyzed by the enzyme histidase c) Deamidation of serine and threonine by a PLP requiring enzyme serine dehydratase d) All of the above 3) The first step in the urea cycle is a condensation of CO2, ammonia, and ATP to form carbamoyl phosphate. The following are true regarding the formation of carbamoyl phosphate, Except : a) The reaction is c...