Unit 4 Test UNE Medical Biochemistry Exam Questions With Complete Solutions | Updated 2026 | Guaranteed Pass

Unit 4 Test UNE Medical Biochemistry Exam Questions With Complete Solutions | Updated 2026 | Guaranteed Pass A deficiency in which of the following enzymes will NOT result in an increase in orotic acid? a. N-acetylglutamate synthetase b. Ornithine transcarbamoylase c. Argininosuccinate synthetase d. Argininosuccinate lyase - answer-N-acetylglutamate synthetase (NAG synthetase Feedback: deficiencies in NAG synthetase or carbamoyl phosphate synthetase I will NOT result in an increase in orotic acid. Which of the following enzymes is correctly paired with its activator? a. N-acetylglutamate synthtase; arginine b. Carbamoyl phosphate synthetase I; ATP c. Glutaminase; citrate d. Arginase; NADH - answer-N-acetylglutamate synthtase; arginine Feedback: arginine (an intermediate of the urea cycle), stimulates the synthesis of NAG by allosterically activating the enzyme N-acetylglutamate synthase Which of the following enzymes is regulated by N-acetylglutamate (NAGs)? a. Carbamoyl phosphate synthetase IIb. Ornithine transcarbamoylase c. Carbamoyl phosphate synthetase I d. Arginosuccinate lyase - answer-Carbamoyl phosphate synthetase I (CPS I) Feedback: CPS I is the regulatory enzyme of the urea cycle and is stimulated by NAG Your patient presents with a deficiency of the enzyme that catalyzes synthesis of N-acetylglutamate (NAGs). Which of the following will be a consequence of this deficiency in the patient? a. increased fatty acids in the blood b. increased amino acids in the blood c. decreased excretion of uric acid d. increased glucose in the blood - answer-Increased amino acids in the blood NAG is an essential activator of CPS I which catalyzes the first step in the urea cycle. Loss of this activator will decrease urea cycle activity, which will increase the amount of amino acids in the blood. The urea cycle takes place in which of the following subcellular locations? a. the cytosol and the mitochondria b. the cytosol only c. the nucleus and the mitochondria d. the mitochondria only - answer-the cytosol and the mitochondria Which of the following non-essential amino acids is synthesized as part of the urea cycle? a. Asparagine b. Aspartate c. Lysine d. Arginine e. Glutamine - answer-arginineSeveral amino acids are intermediates of the urea cycle, having side ammonia groups that join with free Co2 and ammonia to produce net excretion of ammonia as urea. Which of the following amino acids has a nitrogen in its side chain AND is an intermediate of the urea cycle? a. asparagine b. glutamate c. phenylalanine d. arginine - answer-arginine Which of the following reactions of the urea cycle takes place in the mitochondria? a. the synthesis of urea b. the synthesis of argininosuccinate c. the synthesis of carbamoyl phosphate d. the synthesis of arginine - answer-the synthesis of carbamoyl phosphate A 52-year-old male sought medical help complaining about a progressive appearance of hyperchromic papules on the edge of the second finger. Incisional biopsy of one of the spots on his hands and urine sample tested positive for homogentisic acid. Based on these findings a diagnosis of alkaptonuria is made. This diagnosis is consistent with a deficiency in which of the following enzymes? a. phenylalanine hydroxylase b. tyrosinase c. homogentisate oxidase d. α-ketoacid dehydrogenase - answer-homogentisate oxidase Which of the following best describes the process of transamination? a. the transfer of an amino group from an amino acid to a keto-acid b. the release of free ammonia from an amino acid c. the transfer of a carboxyl group to a keto acid - answer-the transfer of an amino group from an amino acid to a keto acid