Test Bank - Lehninger Principles of
Biochemistry, 7th Edition (Nelson, 2018)
Chapter 1-28 | All Chapters
1. Which of the following is the main driving force for protein folding in an
aqueous environment?
A. Ionic interactions
B. Hydrogen bonds
C. Van der Waals interactions
D. Hydrophobic effect
The hydrophobic effect drives nonpolar side chains into the interior of proteins,
minimizing contact with water and stabilizing the folded structure.
2. What is the primary structure of a protein?
A. The overall 3D shape
B. The sequence of amino acids
C. Alpha-helices and beta-sheets
D. Multiple polypeptide chains interacting
The primary structure is the linear sequence of amino acids in a polypeptide chain.
3. In Michaelis-Menten kinetics, what does Km represent?
A. Maximum velocity
,B. Catalytic efficiency
C. Substrate concentration at half-maximal velocity
D. Turnover number
Km reflects the substrate concentration at which the reaction rate is half of Vmax,
indicating enzyme affinity for substrate.
4. Which amino acid contains a thiol group?
A. Alanine
B. Cysteine
C. Serine
D. Lysine
Cysteine has a thiol (-SH) group, which can form disulfide bonds important for
protein structure.
5. Which of the following is a purine?
A. Cytosine
B. Thymine
C. Guanine
D. Uracil
Purines have a two-ring structure; guanine and adenine are purines.
6. What stabilizes the double helix of DNA?
A. Covalent bonds between bases
B. Phosphodiester bonds between base pairs
C. Hydrogen bonding and base stacking interactions
D. Glycosidic linkages
,Base pairing (hydrogen bonding) and π-π interactions between stacked bases
stabilize DNA's helical structure.
7. Which molecule serves as the main energy currency of the cell?
A. NAD+
B. FADH2
C. ATP
D. GTP
ATP stores and transfers energy for cellular reactions via its high-energy
phosphate bonds.
8. The pH at which a molecule carries no net electric charge is called the:
A. Buffering point
B. Ionization constant
C. Isoelectric point
D. pKa
The isoelectric point (pI) is the pH at which a molecule, especially an amino acid or
protein, has no net charge.
9. Which pathway occurs in the cytosol and produces pyruvate?
A. TCA cycle
B. Oxidative phosphorylation
C. Glycolysis
D. Beta-oxidation
Glycolysis occurs in the cytosol and breaks down glucose to pyruvate.
, 10. What is the role of NAD+ in metabolism?
A. Enzyme activator
B. Electron carrier
C. Proton pump
D. Structural protein
NAD+ accepts electrons during redox reactions, becoming NADH, and serves as an
electron carrier.
11. Which complex of the electron transport chain does not pump protons?
A. Complex I
B. Complex III
C. Complex II
D. Complex IV
Complex II (succinate dehydrogenase) transfers electrons but does not contribute
to the proton gradient.
12. The enzyme responsible for carbon fixation in the Calvin cycle is:
A. PEP carboxylase
B. Rubisco
C. Malate dehydrogenase
D. Pyruvate carboxylase
Rubisco catalyzes the fixation of CO₂ to ribulose-1,5-bisphosphate in the Calvin
cycle.
Biochemistry, 7th Edition (Nelson, 2018)
Chapter 1-28 | All Chapters
1. Which of the following is the main driving force for protein folding in an
aqueous environment?
A. Ionic interactions
B. Hydrogen bonds
C. Van der Waals interactions
D. Hydrophobic effect
The hydrophobic effect drives nonpolar side chains into the interior of proteins,
minimizing contact with water and stabilizing the folded structure.
2. What is the primary structure of a protein?
A. The overall 3D shape
B. The sequence of amino acids
C. Alpha-helices and beta-sheets
D. Multiple polypeptide chains interacting
The primary structure is the linear sequence of amino acids in a polypeptide chain.
3. In Michaelis-Menten kinetics, what does Km represent?
A. Maximum velocity
,B. Catalytic efficiency
C. Substrate concentration at half-maximal velocity
D. Turnover number
Km reflects the substrate concentration at which the reaction rate is half of Vmax,
indicating enzyme affinity for substrate.
4. Which amino acid contains a thiol group?
A. Alanine
B. Cysteine
C. Serine
D. Lysine
Cysteine has a thiol (-SH) group, which can form disulfide bonds important for
protein structure.
5. Which of the following is a purine?
A. Cytosine
B. Thymine
C. Guanine
D. Uracil
Purines have a two-ring structure; guanine and adenine are purines.
6. What stabilizes the double helix of DNA?
A. Covalent bonds between bases
B. Phosphodiester bonds between base pairs
C. Hydrogen bonding and base stacking interactions
D. Glycosidic linkages
,Base pairing (hydrogen bonding) and π-π interactions between stacked bases
stabilize DNA's helical structure.
7. Which molecule serves as the main energy currency of the cell?
A. NAD+
B. FADH2
C. ATP
D. GTP
ATP stores and transfers energy for cellular reactions via its high-energy
phosphate bonds.
8. The pH at which a molecule carries no net electric charge is called the:
A. Buffering point
B. Ionization constant
C. Isoelectric point
D. pKa
The isoelectric point (pI) is the pH at which a molecule, especially an amino acid or
protein, has no net charge.
9. Which pathway occurs in the cytosol and produces pyruvate?
A. TCA cycle
B. Oxidative phosphorylation
C. Glycolysis
D. Beta-oxidation
Glycolysis occurs in the cytosol and breaks down glucose to pyruvate.
, 10. What is the role of NAD+ in metabolism?
A. Enzyme activator
B. Electron carrier
C. Proton pump
D. Structural protein
NAD+ accepts electrons during redox reactions, becoming NADH, and serves as an
electron carrier.
11. Which complex of the electron transport chain does not pump protons?
A. Complex I
B. Complex III
C. Complex II
D. Complex IV
Complex II (succinate dehydrogenase) transfers electrons but does not contribute
to the proton gradient.
12. The enzyme responsible for carbon fixation in the Calvin cycle is:
A. PEP carboxylase
B. Rubisco
C. Malate dehydrogenase
D. Pyruvate carboxylase
Rubisco catalyzes the fixation of CO₂ to ribulose-1,5-bisphosphate in the Calvin
cycle.
