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MCQs

Total Questions : 48 | Page 2 of 5 pages
Question 11. Anthranilate synthase, the first enzyme of tryptophan biosynthesis after the branch point shows feedback inhibition and repression due to
  1.    L-tryptophan
  2.    pyruvate
  3.    D-L-tryptophan hydantoin
  4.    L-serine
 Discuss Question
Answer: Option A. -> L-tryptophan
Question 12. The fact that β-oxidation of fatty acids, occurs in the mitochondria whereas fatty acid synthesis occurs in the cytoplasmic matrix, is an example of regulation of enzymatic activity by the __________ mechanism.
  1.    compartmentation
  2.    competitive inhibition
  3.    repression
  4.    induction
 Discuss Question
Answer: Option C. -> repression
Question 13. The affinity of an enzyme for its substrate, when the enzyme has a Km of 0.50 M will be __________ than the affinity of an enzyme for its substrate when the enzyme has a Km of 0.05 M.
  1.    lesser
  2.    greater
  3.    half
  4.    approximately equal
 Discuss Question
Answer: Option A. -> lesser
Question 14. In the reaction, C6H12O6 + 6O2 → 6CO2 + 6H2O + energy, which component is being reduced?
  1.    CO2
  2.    Energy
  3.    H2O
  4.    O2
 Discuss Question
Answer: Option D. -> O2
Question 15. In the reaction, C6H12O6+ 6O2 → 6CO2 + 6H2O + energy, which component is being oxidized?
  1.    H2O
  2.    CO2
  3.    O2
  4.    C6H12O6
 Discuss Question
Answer: Option D. -> C6H12O6
Question 16. Hydrogen and oxygen release enormous amounts of energy when they react. Yet, hydrogen and oxygen can be mixed together in a balloon and nothing will happen. Why?
  1.    The energy of activation to form the transition-state complex is too high to allow the reaction to occur without assistance
  2.    Competitive inhibitors are blocking the reaction from occurring in the active site
  3.    All of these
  4.    There must be contaminating elements in the balloon that prohibit the reaction from occurring
 Discuss Question
Answer: Option B. -> Competitive inhibitors are blocking the reaction from occurring in the active site
Question 17. A substrate binds to its enzyme at a location called the __________ site.
  1.    active
  2.    polypeptide
  3.    coenzyme
  4.    substrate
 Discuss Question
Answer: Option A. -> active
Question 18. Adenosine triphosphate is a type of
  1.    nucleotide
  2.    fatty acid
  3.    amino acid
  4.    steroid
 Discuss Question
Answer: Option A. -> nucleotide
Question 19. An enzyme that is always produced, regardless of the presence of substrates or the end products, is called
  1.    a repressible enzyme
  2.    a constitutive enzyme
  3.    an isoenzyme
  4.    an allosteric enzyme
 Discuss Question
Answer: Option B. -> a constitutive enzyme
Question 20. About 7.3 kcal/mole are released when
  1.    NAD+ is reduced to NADH
  2.    ATP hydrolysis is coupled to sucrose synthesis
  3.    glucose is converted to CO2 and H2O
  4.    the terminal phosphate bond of ATP is broken by hydrolysis
 Discuss Question
Answer: Option C. -> glucose is converted to CO2 and H2O

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