BioChem 210 Exam Module 5 Questions and Ansẉers update

BioChem 210 Exam Module 5
Questions and Ansẉers
2026\2027 update


1. The Pyruvate Dehydrogenase Complex (PDC) catalyzes the
conversion of pyruvate to acetyl-CoA. In which cellular compartment
does this occur?
A) Cytosol
B) Mitochondrial matrix
C) Inner mitochondrial membrane
D) Intermembrane space
Answer: B


2. Which of the following is NOT a cofactor required by the Pyruvate
Dehydrogenase Complex?
A) Thiamine pyrophosphate (TPP)
B) Lipoic acid
C) Biotin
D) FAD
Answer: C (Note: Biotin is used by pyruvate carboxylase, not PDC)


3. The conversion of pyruvate to acetyl-CoA involves the loss of one
carbon as:
A) Methane

,B) Carbon monoxide
C) Carbon dioxide
D) Bicarbonate
Answer: C


4. Which of the following is a potent allosteric inhibitor of the
Pyruvate Dehydrogenase Complex?
A) ADP
B) Pyruvate
C) Acetyl-CoA and NADH
D) AMP
Answer: C


5. The citric acid cycle (Krebs cycle) takes place in the:
A) Cytosol
B) Mitochondrial matrix
C) Inner mitochondrial membrane
D) Endoplasmic reticulum
Answer: B


6. In the first step of the citric acid cycle, acetyl-CoA condenses with
which molecule to form citrate?
A) Succinate
B) Oxaloacetate
C) Alpha-ketoglutarate
D) Malate

, Answer: B


7. Which enzyme catalyzes the condensation of acetyl-CoA and
oxaloacetate?
A) Aconitase
B) Citrate synthase
C) Isocitrate dehydrogenase
D) Malate dehydrogenase
Answer: B


8. The intermediate isocitrate is formed from citrate by the enzyme:
A) Citrate synthase
B) Aconitase
C) Isocitrate dehydrogenase
D) Fumarase
Answer: B


9. The first oxidative decarboxylation step in the citric acid cycle
converts isocitrate to:
A) Succinyl-CoA
B) Alpha-ketoglutarate
C) Oxaloacetate
D) Fumarate
Answer: B