BIOCHEM 210 MODULE 7 EXAM 2026/2027
METABOLISM & ELECTRON TRANSPORT
CHAIN PORTAGE LEARNING | VERIFIED
Q&A | A+ GRADED
SECTION A: METABOLISM FUNDAMENTALS (Questions
1-25)
1. What is metabolism?
Answer: The sum of all chemical reactions that occur in a
living organism.
Rationale: Metabolism encompasses both catabolic
(breakdown) and anabolic (synthesis) reactions that
maintain life.
2. Distinguish between catabolism and anabolism.
Answer: Catabolism is the breakdown of complex
molecules into simpler ones, releasing energy. Anabolism
is the synthesis of complex molecules from simpler ones,
requiring energy.
, Rationale: Catabolic reactions are generally exergonic
(release energy), while anabolic reactions are endergonic
(require energy input).
3. What is the primary energy currency of the cell?
Answer: ATP (Adenosine Triphosphate).
Rationale: ATP stores and transfers energy through its
high-energy phosphate bonds, particularly the terminal
phosphate bond.
4. What is the structure of ATP?
Answer: Adenine base + ribose sugar + three phosphate
groups (α, β, γ).
Rationale: The adenine-ribose forms adenosine, and the
three phosphates create the triphosphate structure with
high-energy phosphoanhydride bonds.
5. How does ATP release energy?
Answer: Hydrolysis of the terminal phosphate bond (γ-
phosphate) yields ADP + Pi and releases ~7.3 kcal/mol.
Rationale: The phosphoanhydride bonds are high-energy
due to electrostatic repulsion and resonance stabilization
of products.
6. What is substrate-level phosphorylation?
, Answer: Direct transfer of a phosphate group from a
high-energy substrate to ADP, forming ATP.
Rationale: Occurs in glycolysis and the TCA cycle without
the need for the electron transport chain.
7. What is oxidative phosphorylation?
Answer: ATP synthesis coupled to the flow of electrons
through the electron transport chain, using the proton
motive force.
Rationale: Occurs in the inner mitochondrial membrane
and requires oxygen as the final electron acceptor.
8. What is the difference between a redox reaction and a
phosphorylation reaction?
Answer: Redox reactions involve electron transfer, while
phosphorylation reactions involve phosphate transfer.
Rationale: Redox reactions change oxidation states;
phosphorylation adds phosphate groups to molecules.
9. Define oxidation and reduction.
Answer: Oxidation is loss of electrons (or hydrogen),
reduction is gain of electrons (or hydrogen).
Rationale: OIL RIG: Oxidation Is Loss, Reduction Is Gain
of electrons.
, 10. What are coenzymes in metabolism?
Answer: Small organic molecules that assist enzymes by
carrying electrons, atoms, or functional groups.
Rationale: Examples include NAD+, FAD, and Coenzyme
A.
11. What is the role of NAD+ in metabolism?
Answer: NAD+ acts as an electron carrier, accepting two
electrons and one proton to become NADH.
Rationale: NAD+/NADH couples catabolic oxidation
reactions to ATP production.
12. What is the role of FAD in metabolism?
Answer: FAD accepts two electrons and two protons to
become FADH2.
Rationale: FADH2 enters the electron transport chain at
Complex II, contributing fewer protons to the proton
gradient than NADH.
13. What is Coenzyme A (CoA)?
Answer: A carrier of acyl groups, particularly acetyl
groups in acetyl-CoA.
Rationale: CoA has a reactive thiol group that forms
high-energy thioester bonds.
METABOLISM & ELECTRON TRANSPORT
CHAIN PORTAGE LEARNING | VERIFIED
Q&A | A+ GRADED
SECTION A: METABOLISM FUNDAMENTALS (Questions
1-25)
1. What is metabolism?
Answer: The sum of all chemical reactions that occur in a
living organism.
Rationale: Metabolism encompasses both catabolic
(breakdown) and anabolic (synthesis) reactions that
maintain life.
2. Distinguish between catabolism and anabolism.
Answer: Catabolism is the breakdown of complex
molecules into simpler ones, releasing energy. Anabolism
is the synthesis of complex molecules from simpler ones,
requiring energy.
, Rationale: Catabolic reactions are generally exergonic
(release energy), while anabolic reactions are endergonic
(require energy input).
3. What is the primary energy currency of the cell?
Answer: ATP (Adenosine Triphosphate).
Rationale: ATP stores and transfers energy through its
high-energy phosphate bonds, particularly the terminal
phosphate bond.
4. What is the structure of ATP?
Answer: Adenine base + ribose sugar + three phosphate
groups (α, β, γ).
Rationale: The adenine-ribose forms adenosine, and the
three phosphates create the triphosphate structure with
high-energy phosphoanhydride bonds.
5. How does ATP release energy?
Answer: Hydrolysis of the terminal phosphate bond (γ-
phosphate) yields ADP + Pi and releases ~7.3 kcal/mol.
Rationale: The phosphoanhydride bonds are high-energy
due to electrostatic repulsion and resonance stabilization
of products.
6. What is substrate-level phosphorylation?
, Answer: Direct transfer of a phosphate group from a
high-energy substrate to ADP, forming ATP.
Rationale: Occurs in glycolysis and the TCA cycle without
the need for the electron transport chain.
7. What is oxidative phosphorylation?
Answer: ATP synthesis coupled to the flow of electrons
through the electron transport chain, using the proton
motive force.
Rationale: Occurs in the inner mitochondrial membrane
and requires oxygen as the final electron acceptor.
8. What is the difference between a redox reaction and a
phosphorylation reaction?
Answer: Redox reactions involve electron transfer, while
phosphorylation reactions involve phosphate transfer.
Rationale: Redox reactions change oxidation states;
phosphorylation adds phosphate groups to molecules.
9. Define oxidation and reduction.
Answer: Oxidation is loss of electrons (or hydrogen),
reduction is gain of electrons (or hydrogen).
Rationale: OIL RIG: Oxidation Is Loss, Reduction Is Gain
of electrons.
, 10. What are coenzymes in metabolism?
Answer: Small organic molecules that assist enzymes by
carrying electrons, atoms, or functional groups.
Rationale: Examples include NAD+, FAD, and Coenzyme
A.
11. What is the role of NAD+ in metabolism?
Answer: NAD+ acts as an electron carrier, accepting two
electrons and one proton to become NADH.
Rationale: NAD+/NADH couples catabolic oxidation
reactions to ATP production.
12. What is the role of FAD in metabolism?
Answer: FAD accepts two electrons and two protons to
become FADH2.
Rationale: FADH2 enters the electron transport chain at
Complex II, contributing fewer protons to the proton
gradient than NADH.
13. What is Coenzyme A (CoA)?
Answer: A carrier of acyl groups, particularly acetyl
groups in acetyl-CoA.
Rationale: CoA has a reactive thiol group that forms
high-energy thioester bonds.
