Advanced Biochemistry Multiple Choice
Questions (MCQs) with Answers and
Explanations for Lehninger Principles of
Biochemistry 8th Edition and University
Examinations
1. A mutation decreases the affinity of hemoglobin for 2,3-bisphosphoglycerate. Which
effect is most likely to occur?
A. Increased oxygen delivery to tissues
B. Enhanced Bohr effect
C. Increased oxygen affinity of hemoglobin
D. Increased carbon dioxide transport
Explanation: Reduced binding of 2,3-bisphosphoglycerate stabilizes the R state of hemoglobin,
increasing oxygen affinity and reducing oxygen release to peripheral tissues.
2. During oxidative phosphorylation, uncoupling proteins primarily cause which effect?
A. Increased ATP synthesis efficiency
B. Inhibition of electron transport
C. Reduced oxygen consumption
D. Dissipation of the proton gradient as heat
Explanation: Uncoupling proteins allow protons to re-enter the mitochondrial matrix without
ATP generation, releasing energy as heat.
3. Which enzyme catalyzes the committed step of glycolysis?
A. Hexokinase
B. Pyruvate kinase
C. Phosphoglycerate kinase
, D. Phosphofructokinase-1
Explanation: Phosphofructokinase-1 catalyzes fructose-6-phosphate conversion to fructose-1,6-
bisphosphate and represents the major regulatory step.
4. A deficiency of pyruvate dehydrogenase would most directly result in accumulation of:
A. Acetyl-CoA
B. Citrate
C. Pyruvate
D. Succinyl-CoA
Explanation: Pyruvate cannot be converted efficiently into acetyl-CoA, causing pyruvate
accumulation and increased lactate production.
5. Which amino acid is exclusively ketogenic?
A. Isoleucine
B. Phenylalanine
C. Tyrosine
D. Leucine
Explanation: Leucine and lysine are exclusively ketogenic because they yield acetyl-CoA or
acetoacetate but not glucose precursors.
6. Competitive inhibition is characterized by:
A. Decreased Vmax and unchanged Km
B. Decreased Vmax and decreased Km
C. Unchanged Vmax and increased Km
D. Increased Vmax and decreased Km
Explanation: Competitive inhibitors increase the apparent Km without affecting maximum
velocity because sufficient substrate can overcome inhibition.
7. Which cofactor is directly involved in one-carbon transfer reactions?
Questions (MCQs) with Answers and
Explanations for Lehninger Principles of
Biochemistry 8th Edition and University
Examinations
1. A mutation decreases the affinity of hemoglobin for 2,3-bisphosphoglycerate. Which
effect is most likely to occur?
A. Increased oxygen delivery to tissues
B. Enhanced Bohr effect
C. Increased oxygen affinity of hemoglobin
D. Increased carbon dioxide transport
Explanation: Reduced binding of 2,3-bisphosphoglycerate stabilizes the R state of hemoglobin,
increasing oxygen affinity and reducing oxygen release to peripheral tissues.
2. During oxidative phosphorylation, uncoupling proteins primarily cause which effect?
A. Increased ATP synthesis efficiency
B. Inhibition of electron transport
C. Reduced oxygen consumption
D. Dissipation of the proton gradient as heat
Explanation: Uncoupling proteins allow protons to re-enter the mitochondrial matrix without
ATP generation, releasing energy as heat.
3. Which enzyme catalyzes the committed step of glycolysis?
A. Hexokinase
B. Pyruvate kinase
C. Phosphoglycerate kinase
, D. Phosphofructokinase-1
Explanation: Phosphofructokinase-1 catalyzes fructose-6-phosphate conversion to fructose-1,6-
bisphosphate and represents the major regulatory step.
4. A deficiency of pyruvate dehydrogenase would most directly result in accumulation of:
A. Acetyl-CoA
B. Citrate
C. Pyruvate
D. Succinyl-CoA
Explanation: Pyruvate cannot be converted efficiently into acetyl-CoA, causing pyruvate
accumulation and increased lactate production.
5. Which amino acid is exclusively ketogenic?
A. Isoleucine
B. Phenylalanine
C. Tyrosine
D. Leucine
Explanation: Leucine and lysine are exclusively ketogenic because they yield acetyl-CoA or
acetoacetate but not glucose precursors.
6. Competitive inhibition is characterized by:
A. Decreased Vmax and unchanged Km
B. Decreased Vmax and decreased Km
C. Unchanged Vmax and increased Km
D. Increased Vmax and decreased Km
Explanation: Competitive inhibitors increase the apparent Km without affecting maximum
velocity because sufficient substrate can overcome inhibition.
7. Which cofactor is directly involved in one-carbon transfer reactions?
