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7.2 Urea Cycle — Test 1
Q1. The end product of protein (amino acid nitrogen) metabolism in humans is:✓ Urea
Q2. To produce one urea molecule via the urea cycle, how much ATP is required?✓ 3 ATP
Q3. In the urea cycle, the formation of one urea molecule requires:✓ 3 ATP
Q4. Why are urea-cycle enzymes compartmentalized between mitochondria and cytosol?✓ To prevent reductive amination of α-ketoglutarate in the mitochondria
Q5. In the urea cycle, the enzymes are compartmentalized in mitochondria and cytosol because:✓ To prevent reductive amination of α-ketoglutarate in the mitochondria
Q6. Identify the cellular localization of ornithine transcarbamoylase (OTC) and argininosuccinate lyase (ASL):✓ OTC – mitochondria; ASL – cytosol
Q7. The urea cycle takes place in:✓ Mitochondria and cytosol of hepatocytes
Q8. The urea cycle occurs in the:✓ Mitochondria and cytoplasm
Q9. Which is the rate-limiting enzyme of the urea cycle?✓ Carbamoyl phosphate synthetase-I
Q10. The rate-limiting factor of the urea cycle is:✓ Carbamoyl phosphate synthetase
Q11. The two nitrogen atoms in urea are contributed by:✓ Ammonia and aspartic acid
Q12. Urea is synthesized in the:✓ Both cytoplasm and mitochondria
Q13. The number of ammonia and CO₂ molecules used in one turn of the urea cycle, respectively, are:✓ 1 and 2
Q14. Which statement about carbamoyl phosphate synthesis by CPS-I is INCORRECT?✓ The reaction is reversible
Q15. Urea cycle enzymes: 1) are found in mitochondria and cytosol; 2) are seen in amoeba; 3) facilitate removal of toxic excess ammonia from blood; 4) are also found in some plants. Which option lists the correct statements?✓ 1 & 3
Q16. The two nitrogen atoms in urea are contributed by:✓ Ammonia and aspartate