CHEM 210 Biochemistry — 100 Practice Exam questions with
100 % Verified Correct Answers & Explanations.
1. Which statement best describes the primary structure of a protein?
A. The three-dimensional arrangement of the entire protein
B. The sequence of amino acids in the polypeptide chain
C. The arrangement of alpha helices and beta sheets
D. The association of multiple polypeptide chains
Correct Answer: B. The sequence of amino acids in the polypeptide chain
Explanation: Primary protein structure refers to the specific linear sequence
of amino acids joined by peptide bonds. This sequence determines how the
protein folds into higher levels of structure and ultimately influences its
function.
2. Which amino acid contains a thiol (-SH) group in its side chain?
A. Methionine
B. Cysteine
C. Serine
D. Tyrosine
Correct Answer: B. Cysteine
Explanation: Cysteine contains a sulfhydryl or thiol group. Two cysteine
residues can undergo oxidation to form a disulfide bond, which can stabilize
the three-dimensional structure of proteins.
3. Which amino acid is classified as an aromatic amino acid?
A. Glycine
B. Alanine
C. Phenylalanine
D. Lysine
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,Correct Answer: C. Phenylalanine
Explanation: Phenylalanine contains an aromatic benzyl side chain. Other
aromatic amino acids include tyrosine and tryptophan. Their aromatic rings
contribute to protein structure and interactions.
4. What type of bond links amino acids together in a polypeptide?
A. Glycosidic bond
B. Phosphodiester bond
C. Peptide bond
D. Hydrogen bond
Correct Answer: C. Peptide bond
Explanation: A peptide bond forms between the carboxyl group of one amino
acid and the amino group of another amino acid through a condensation
reaction. The resulting polypeptide has a specific amino-terminal and
carboxyl-terminal direction.
5. Which level of protein structure is primarily stabilized by hydrogen
bonding between backbone carbonyl and amide groups?
A. Primary structure
B. Secondary structure
C. Tertiary structure
D. Quaternary structure
Correct Answer: B. Secondary structure
Explanation: Secondary protein structure includes alpha helices and beta-
pleated sheets. These structures are primarily stabilized by hydrogen bonds
between atoms in the protein backbone rather than interactions between side
chains.
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,6. Which amino acid is considered nonpolar?
A. Lysine
B. Aspartate
C. Valine
D. Glutamate
Correct Answer: C. Valine
Explanation: Valine has a branched, hydrophobic side chain and is classified
as a nonpolar amino acid. Nonpolar amino acids commonly become buried
within the interior of globular proteins away from water.
7. What is the primary function of an enzyme?
A. Increase the activation energy of a reaction
B. Decrease the activation energy required for a reaction
C. Change the equilibrium constant of a reaction
D. Become permanently consumed during a reaction
Correct Answer: B. Decrease the activation energy required for a
reaction
Explanation: Enzymes are biological catalysts that accelerate chemical
reactions by lowering the activation energy. They are not permanently
consumed and generally do not change the overall equilibrium or
thermodynamic favorability of the reaction.
8. Which region of an enzyme directly binds the substrate?
A. Allosteric site
B. Active site
C. Peptide terminus
D. Phosphate group
Correct Answer: B. Active site
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, Explanation: The active site is the specific region of an enzyme where
substrate binding and catalytic activity occur. Its three-dimensional structure
creates chemical interactions that provide specificity for particular substrates.
9. Which factor can cause an enzyme to lose its functional three-dimensional
structure?
A. Appropriate substrate concentration
B. Extreme temperature
C. Normal physiological pH
D. Adequate cofactor availability
Correct Answer: B. Extreme temperature
Explanation: Extreme temperatures can disrupt the noncovalent interactions
maintaining protein structure, causing denaturation. Once an enzyme loses its
proper conformation, its active site may no longer function correctly.
10. In Michaelis-Menten kinetics, what does Km represent?
A. Maximum enzyme concentration
B. Substrate concentration at which reaction velocity is half of Vmax
C. Total amount of product formed
D. Enzyme concentration required to denature the substrate
Correct Answer: B. Substrate concentration at which reaction velocity is
half of Vmax
Explanation: Km is the substrate concentration at which an enzyme-
catalyzed reaction proceeds at half its maximum velocity. For many enzymes,
a lower Km indicates higher apparent affinity for the substrate.
11. Which type of inhibition can usually be overcome by increasing substrate
concentration?
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100 % Verified Correct Answers & Explanations.
1. Which statement best describes the primary structure of a protein?
A. The three-dimensional arrangement of the entire protein
B. The sequence of amino acids in the polypeptide chain
C. The arrangement of alpha helices and beta sheets
D. The association of multiple polypeptide chains
Correct Answer: B. The sequence of amino acids in the polypeptide chain
Explanation: Primary protein structure refers to the specific linear sequence
of amino acids joined by peptide bonds. This sequence determines how the
protein folds into higher levels of structure and ultimately influences its
function.
2. Which amino acid contains a thiol (-SH) group in its side chain?
A. Methionine
B. Cysteine
C. Serine
D. Tyrosine
Correct Answer: B. Cysteine
Explanation: Cysteine contains a sulfhydryl or thiol group. Two cysteine
residues can undergo oxidation to form a disulfide bond, which can stabilize
the three-dimensional structure of proteins.
3. Which amino acid is classified as an aromatic amino acid?
A. Glycine
B. Alanine
C. Phenylalanine
D. Lysine
1|Page
,Correct Answer: C. Phenylalanine
Explanation: Phenylalanine contains an aromatic benzyl side chain. Other
aromatic amino acids include tyrosine and tryptophan. Their aromatic rings
contribute to protein structure and interactions.
4. What type of bond links amino acids together in a polypeptide?
A. Glycosidic bond
B. Phosphodiester bond
C. Peptide bond
D. Hydrogen bond
Correct Answer: C. Peptide bond
Explanation: A peptide bond forms between the carboxyl group of one amino
acid and the amino group of another amino acid through a condensation
reaction. The resulting polypeptide has a specific amino-terminal and
carboxyl-terminal direction.
5. Which level of protein structure is primarily stabilized by hydrogen
bonding between backbone carbonyl and amide groups?
A. Primary structure
B. Secondary structure
C. Tertiary structure
D. Quaternary structure
Correct Answer: B. Secondary structure
Explanation: Secondary protein structure includes alpha helices and beta-
pleated sheets. These structures are primarily stabilized by hydrogen bonds
between atoms in the protein backbone rather than interactions between side
chains.
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,6. Which amino acid is considered nonpolar?
A. Lysine
B. Aspartate
C. Valine
D. Glutamate
Correct Answer: C. Valine
Explanation: Valine has a branched, hydrophobic side chain and is classified
as a nonpolar amino acid. Nonpolar amino acids commonly become buried
within the interior of globular proteins away from water.
7. What is the primary function of an enzyme?
A. Increase the activation energy of a reaction
B. Decrease the activation energy required for a reaction
C. Change the equilibrium constant of a reaction
D. Become permanently consumed during a reaction
Correct Answer: B. Decrease the activation energy required for a
reaction
Explanation: Enzymes are biological catalysts that accelerate chemical
reactions by lowering the activation energy. They are not permanently
consumed and generally do not change the overall equilibrium or
thermodynamic favorability of the reaction.
8. Which region of an enzyme directly binds the substrate?
A. Allosteric site
B. Active site
C. Peptide terminus
D. Phosphate group
Correct Answer: B. Active site
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, Explanation: The active site is the specific region of an enzyme where
substrate binding and catalytic activity occur. Its three-dimensional structure
creates chemical interactions that provide specificity for particular substrates.
9. Which factor can cause an enzyme to lose its functional three-dimensional
structure?
A. Appropriate substrate concentration
B. Extreme temperature
C. Normal physiological pH
D. Adequate cofactor availability
Correct Answer: B. Extreme temperature
Explanation: Extreme temperatures can disrupt the noncovalent interactions
maintaining protein structure, causing denaturation. Once an enzyme loses its
proper conformation, its active site may no longer function correctly.
10. In Michaelis-Menten kinetics, what does Km represent?
A. Maximum enzyme concentration
B. Substrate concentration at which reaction velocity is half of Vmax
C. Total amount of product formed
D. Enzyme concentration required to denature the substrate
Correct Answer: B. Substrate concentration at which reaction velocity is
half of Vmax
Explanation: Km is the substrate concentration at which an enzyme-
catalyzed reaction proceeds at half its maximum velocity. For many enzymes,
a lower Km indicates higher apparent affinity for the substrate.
11. Which type of inhibition can usually be overcome by increasing substrate
concentration?
4|Page
