Portage Learning | CHEM 210 Biochemistry
CHEM 210 Biochemistry Comprehensive
Examination (Modules 1-8) 2026/2027 |
Verified Questions
Portage Learning | CHEM 210 Biochemistry | University-Level Chemistry Students
240 Verified Questions | 4 Core Domains | Academic Year 2026/2027
Prepared by
Portage Learning | CHEM 210 Biochemistry
Comprehensive Examination (All Modules 1-8 Combined) Actual Exam | Academic Year
2026/2027
CHEM 210 Biochemistry Comprehensive Examination (Modules 1-8) 2026/2027 | Verified Questions
Page 1 of 83
,INTRODUCTION
This certification-level set contains 240 original questions written for the Portage Learning CHEM 210
Biochemistry Comprehensive Examination, covering all 8 modules of the course in a single integrated
body of material, and every item was composed to reinforce the official course objectives for actual exam
readiness and scientific proficiency in biochemistry. The items are organized across four core domains
that mirror the module objectives of the official Portage Learning CHEM 210 curriculum: Domain 1,
Biomolecules and Protein Structure, with 60 questions; Domain 2, Enzyme Kinetics and Metabolism, with
60 questions; Domain 3, Carbohydrate and Lipid Biochemistry, with 60 questions; and Domain 4, Nucleic
Acids, Gene Expression, and Bioenergetics, with 60 questions. Every question is followed by one correct
option and a rationale that shows the underlying chemistry, the numerical reasoning where a calculation
is required, and the molecular logic that links the structure of a biomolecule to its behavior in a metabolic
pathway. No two questions in the set depend on the same calculation, the same rule, or the same
interpretation of data, so the collection gives the candidate broad coverage of the official module
objectives. All content is original and aligned to the 2026/2027 academic year for candidates who are
working toward the actual examination.
ACTUAL QUESTIONS
Domain 1: Biomolecules and Protein Structure
Question 1. Liquid water has an unusually high boiling point and surface tension for so
small a molecule. Which structural feature of water accounts for these properties?
A. Water is a linear molecule that carries a permanent dipole.
B. Water interacts with its neighbors only through London dispersion forces.
C. Two polar O-H bonds on a bent molecule let each water molecule hydrogen-bond with as many as
four neighbors.
D. Water forms strong covalent bonds with four surrounding molecules.
Correct Answer: C
Rationale: The oxygen atom of water is more electronegative than hydrogen, so each O-H bond is polar,
and the molecule is bent at roughly 104.5 degrees rather than linear, which places the two bond dipoles
at an angle and gives the molecule a large net dipole moment. The positive hydrogens of one molecule
are attracted to the lone pairs of oxygen on its neighbors, so an extended hydrogen-bond network
forms, as presented in the Portage Learning CHEM 210 module on the chemistry of water and in
Lehninger Principles of Biochemistry.
Question 2. A folded globular protein is placed in water. Which interaction provides the
principal driving force for its hydrophobic side chains to cluster in the interior?
A. The formation of covalent bonds between nonpolar side chains.
B. The direct attraction of nonpolar side chains for one another.
C. A decrease in the entropy of the solvent as clusters form.
D. The increase in entropy of the surrounding water when ordered solvent shells are released.
Correct Answer: D
Rationale: Nonpolar groups cannot hydrogen-bond with water, so the solvent organizes itself into
ordered, cage-like shells around them and loses entropy. When those groups come together, the ordered
water is released into the bulk phase and solvent entropy rises, which makes the overall free-energy
change favorable. The clustering is therefore entropically driven rather than the result of a strong
attraction between the nonpolar groups themselves, a point emphasized in both the CHEM 210 module
objectives and Lehninger Principles of Biochemistry.
CHEM 210 Biochemistry Comprehensive Examination (Modules 1-8) 2026/2027 | Verified Questions
Page 2 of 83
,Question 3. A buffer is prepared from a weak acid whose pKa is 4.76. The measured pH of
the buffer is 5.36. What is the ratio of conjugate base to weak acid in this buffer?
A. About 1 to 4
B. About 4 to 1
C. About 2 to 1
D. About 1 to 1
Correct Answer: B
Rationale: The Henderson-Hasselbalch relationship states that pH equals pKa plus the logarithm of the
ratio of conjugate base to weak acid. Substituting the measured values gives 5.36 minus 4.76, which
equals 0.60, so the logarithm of the ratio is 0.60 and the ratio itself is the antilogarithm, approximately
4 to 1. The Portage Learning CHEM 210 module on acid-base chemistry applies this relationship to
biological buffers, and Lehninger Principles of Biochemistry uses the same treatment when it introduces
the bicarbonate and phosphate systems of the body.
Question 4. A researcher must maintain an aqueous medium at pH 7.2 while studying a
mammalian enzyme. Which weak acid would be the most suitable buffering agent?
A. A weak acid with a pKa near 7.2
B. A weak acid with a pKa near 4.0
C. A weak acid with a pKa near 10.5
D. A strong acid such as hydrochloric acid
Correct Answer: A
Rationale: A buffering system resists changes in pH most effectively within roughly one pH unit of its
pKa, because that is the range in which the conjugate acid and conjugate base are both present at
appreciable concentration. Choosing a weak acid with a pKa near 7.2 places the working pH at the
midpoint of the buffering range, where buffering capacity is greatest. The Portage Learning CHEM 210
curriculum and Lehninger Principles of Biochemistry both link buffer selection to the pKa of the chosen
species rather than to its concentration alone.
Question 5. Which pair of amino acids contains only side chains classified as nonpolar and
aliphatic?
A. Lysine and arginine
B. Leucine and valine
C. Aspartate and glutamate
D. Serine and threonine
Correct Answer: B
Rationale: Leucine and valine carry branched hydrocarbon side chains composed solely of carbon and
hydrogen, so they are nonpolar and aliphatic and prefer the interior of a folded protein. Lysine and
arginine carry positively charged amino groups, aspartate and glutamate carry negatively charged
carboxylates, and serine and threonine carry polar hydroxyl groups. The Portage Learning CHEM 210
module on amino acid classification organizes the residues by side-chain chemistry, as does Berg
Biochemistry, because that chemistry governs where each residue is found in a folded structure.
Question 6. At physiological pH, which amino acid side chains carry a positive charge?
A. The side chains of aspartate and glutamate
B. The side chains of serine and cysteine
C. The side chains of lysine and arginine
D. The side chains of phenylalanine and tryptophan
Correct Answer: C
Rationale: The lysine side chain ends in a primary amino group whose pKa is near 10.5, and the
arginine side chain ends in a guanidinium group whose pKa is near 12.5, so both are protonated and
positively charged at pH 7.4. Aspartate and glutamate are deprotonated and negative at that pH, while
serine, cysteine, phenylalanine, and tryptophan carry uncharged side chains. The Portage Learning
CHEM 210 Biochemistry Comprehensive Examination (Modules 1-8) 2026/2027 | Verified Questions
Page 3 of 83
, CHEM 210 module objectives require the candidate to predict side-chain charge from pKa values, a skill
also developed in Lehninger Principles of Biochemistry.
Question 7. A purified protein is quantified by its absorbance at 280 nm. Which property of
the protein makes this measurement possible?
A. The peptide backbone absorbs ultraviolet light at 280 nm.
B. The sulfhydryl groups of cysteine absorb ultraviolet light at 280 nm.
C. The aliphatic side chains of leucine and isoleucine absorb ultraviolet light at 280 nm.
D. The aromatic rings of tryptophan and tyrosine absorb ultraviolet light at that wavelength.
Correct Answer: D
Rationale: The conjugated pi-electron systems of the indole ring of tryptophan and the phenolic ring of
tyrosine produce strong absorbance near 280 nm, so the reading tracks protein concentration when the
aromatic content of the protein is known. The peptide bond absorbs near 214 nm instead, cysteine
absorbs weakly, and aliphatic side chains have no useful absorbance in this region. The Portage
Learning CHEM 210 module on protein analysis and Berg Biochemistry both use this relationship to
introduce spectrophotometric protein quantification.
Question 8. Which amino acid forms covalent cross-links that stabilize the three-
dimensional structure of many secreted proteins?
A. Methionine
B. Proline
C. Cysteine
D. Histidine
Correct Answer: C
Rationale: The thiol group of cysteine can be oxidized to form a disulfide bond with the thiol of a second
cysteine, and the resulting linkage holds distant parts of a polypeptide chain together. Methionine
contains sulfur but in a thioether that cannot form this linkage, while proline and histidine have no
sulfur at all. The Portage Learning CHEM 210 module on protein structure and Lehninger Principles of
Biochemistry both present disulfide bond formation as a covalent contribution to tertiary and
quaternary structure, particularly in secreted and extracellular proteins.
Question 9. Which amino acids carry a hydroxyl group on their side chain and can be
phosphorylated by protein kinases?
A. Serine and threonine
B. Alanine and glycine
C. Valine and leucine
D. Phenylalanine and tryptophan
Correct Answer: A
Rationale: Serine and threonine side chains terminate in a primary or secondary alcohol, and the
oxygen of that hydroxyl is a competent nucleophile that protein kinases can attack to form a phosphate
ester. Alanine, glycine, valine, leucine, phenylalanine, and tryptophan carry no hydroxyl group and
cannot be phosphorylated. The Portage Learning CHEM 210 module on post-translational modification
and Berg Biochemistry both present O-linked phosphorylation of serine, threonine, and tyrosine as a
central regulatory device in cell signaling.
CHEM 210 Biochemistry Comprehensive Examination (Modules 1-8) 2026/2027 | Verified Questions
Page 4 of 83
CHEM 210 Biochemistry Comprehensive
Examination (Modules 1-8) 2026/2027 |
Verified Questions
Portage Learning | CHEM 210 Biochemistry | University-Level Chemistry Students
240 Verified Questions | 4 Core Domains | Academic Year 2026/2027
Prepared by
Portage Learning | CHEM 210 Biochemistry
Comprehensive Examination (All Modules 1-8 Combined) Actual Exam | Academic Year
2026/2027
CHEM 210 Biochemistry Comprehensive Examination (Modules 1-8) 2026/2027 | Verified Questions
Page 1 of 83
,INTRODUCTION
This certification-level set contains 240 original questions written for the Portage Learning CHEM 210
Biochemistry Comprehensive Examination, covering all 8 modules of the course in a single integrated
body of material, and every item was composed to reinforce the official course objectives for actual exam
readiness and scientific proficiency in biochemistry. The items are organized across four core domains
that mirror the module objectives of the official Portage Learning CHEM 210 curriculum: Domain 1,
Biomolecules and Protein Structure, with 60 questions; Domain 2, Enzyme Kinetics and Metabolism, with
60 questions; Domain 3, Carbohydrate and Lipid Biochemistry, with 60 questions; and Domain 4, Nucleic
Acids, Gene Expression, and Bioenergetics, with 60 questions. Every question is followed by one correct
option and a rationale that shows the underlying chemistry, the numerical reasoning where a calculation
is required, and the molecular logic that links the structure of a biomolecule to its behavior in a metabolic
pathway. No two questions in the set depend on the same calculation, the same rule, or the same
interpretation of data, so the collection gives the candidate broad coverage of the official module
objectives. All content is original and aligned to the 2026/2027 academic year for candidates who are
working toward the actual examination.
ACTUAL QUESTIONS
Domain 1: Biomolecules and Protein Structure
Question 1. Liquid water has an unusually high boiling point and surface tension for so
small a molecule. Which structural feature of water accounts for these properties?
A. Water is a linear molecule that carries a permanent dipole.
B. Water interacts with its neighbors only through London dispersion forces.
C. Two polar O-H bonds on a bent molecule let each water molecule hydrogen-bond with as many as
four neighbors.
D. Water forms strong covalent bonds with four surrounding molecules.
Correct Answer: C
Rationale: The oxygen atom of water is more electronegative than hydrogen, so each O-H bond is polar,
and the molecule is bent at roughly 104.5 degrees rather than linear, which places the two bond dipoles
at an angle and gives the molecule a large net dipole moment. The positive hydrogens of one molecule
are attracted to the lone pairs of oxygen on its neighbors, so an extended hydrogen-bond network
forms, as presented in the Portage Learning CHEM 210 module on the chemistry of water and in
Lehninger Principles of Biochemistry.
Question 2. A folded globular protein is placed in water. Which interaction provides the
principal driving force for its hydrophobic side chains to cluster in the interior?
A. The formation of covalent bonds between nonpolar side chains.
B. The direct attraction of nonpolar side chains for one another.
C. A decrease in the entropy of the solvent as clusters form.
D. The increase in entropy of the surrounding water when ordered solvent shells are released.
Correct Answer: D
Rationale: Nonpolar groups cannot hydrogen-bond with water, so the solvent organizes itself into
ordered, cage-like shells around them and loses entropy. When those groups come together, the ordered
water is released into the bulk phase and solvent entropy rises, which makes the overall free-energy
change favorable. The clustering is therefore entropically driven rather than the result of a strong
attraction between the nonpolar groups themselves, a point emphasized in both the CHEM 210 module
objectives and Lehninger Principles of Biochemistry.
CHEM 210 Biochemistry Comprehensive Examination (Modules 1-8) 2026/2027 | Verified Questions
Page 2 of 83
,Question 3. A buffer is prepared from a weak acid whose pKa is 4.76. The measured pH of
the buffer is 5.36. What is the ratio of conjugate base to weak acid in this buffer?
A. About 1 to 4
B. About 4 to 1
C. About 2 to 1
D. About 1 to 1
Correct Answer: B
Rationale: The Henderson-Hasselbalch relationship states that pH equals pKa plus the logarithm of the
ratio of conjugate base to weak acid. Substituting the measured values gives 5.36 minus 4.76, which
equals 0.60, so the logarithm of the ratio is 0.60 and the ratio itself is the antilogarithm, approximately
4 to 1. The Portage Learning CHEM 210 module on acid-base chemistry applies this relationship to
biological buffers, and Lehninger Principles of Biochemistry uses the same treatment when it introduces
the bicarbonate and phosphate systems of the body.
Question 4. A researcher must maintain an aqueous medium at pH 7.2 while studying a
mammalian enzyme. Which weak acid would be the most suitable buffering agent?
A. A weak acid with a pKa near 7.2
B. A weak acid with a pKa near 4.0
C. A weak acid with a pKa near 10.5
D. A strong acid such as hydrochloric acid
Correct Answer: A
Rationale: A buffering system resists changes in pH most effectively within roughly one pH unit of its
pKa, because that is the range in which the conjugate acid and conjugate base are both present at
appreciable concentration. Choosing a weak acid with a pKa near 7.2 places the working pH at the
midpoint of the buffering range, where buffering capacity is greatest. The Portage Learning CHEM 210
curriculum and Lehninger Principles of Biochemistry both link buffer selection to the pKa of the chosen
species rather than to its concentration alone.
Question 5. Which pair of amino acids contains only side chains classified as nonpolar and
aliphatic?
A. Lysine and arginine
B. Leucine and valine
C. Aspartate and glutamate
D. Serine and threonine
Correct Answer: B
Rationale: Leucine and valine carry branched hydrocarbon side chains composed solely of carbon and
hydrogen, so they are nonpolar and aliphatic and prefer the interior of a folded protein. Lysine and
arginine carry positively charged amino groups, aspartate and glutamate carry negatively charged
carboxylates, and serine and threonine carry polar hydroxyl groups. The Portage Learning CHEM 210
module on amino acid classification organizes the residues by side-chain chemistry, as does Berg
Biochemistry, because that chemistry governs where each residue is found in a folded structure.
Question 6. At physiological pH, which amino acid side chains carry a positive charge?
A. The side chains of aspartate and glutamate
B. The side chains of serine and cysteine
C. The side chains of lysine and arginine
D. The side chains of phenylalanine and tryptophan
Correct Answer: C
Rationale: The lysine side chain ends in a primary amino group whose pKa is near 10.5, and the
arginine side chain ends in a guanidinium group whose pKa is near 12.5, so both are protonated and
positively charged at pH 7.4. Aspartate and glutamate are deprotonated and negative at that pH, while
serine, cysteine, phenylalanine, and tryptophan carry uncharged side chains. The Portage Learning
CHEM 210 Biochemistry Comprehensive Examination (Modules 1-8) 2026/2027 | Verified Questions
Page 3 of 83
, CHEM 210 module objectives require the candidate to predict side-chain charge from pKa values, a skill
also developed in Lehninger Principles of Biochemistry.
Question 7. A purified protein is quantified by its absorbance at 280 nm. Which property of
the protein makes this measurement possible?
A. The peptide backbone absorbs ultraviolet light at 280 nm.
B. The sulfhydryl groups of cysteine absorb ultraviolet light at 280 nm.
C. The aliphatic side chains of leucine and isoleucine absorb ultraviolet light at 280 nm.
D. The aromatic rings of tryptophan and tyrosine absorb ultraviolet light at that wavelength.
Correct Answer: D
Rationale: The conjugated pi-electron systems of the indole ring of tryptophan and the phenolic ring of
tyrosine produce strong absorbance near 280 nm, so the reading tracks protein concentration when the
aromatic content of the protein is known. The peptide bond absorbs near 214 nm instead, cysteine
absorbs weakly, and aliphatic side chains have no useful absorbance in this region. The Portage
Learning CHEM 210 module on protein analysis and Berg Biochemistry both use this relationship to
introduce spectrophotometric protein quantification.
Question 8. Which amino acid forms covalent cross-links that stabilize the three-
dimensional structure of many secreted proteins?
A. Methionine
B. Proline
C. Cysteine
D. Histidine
Correct Answer: C
Rationale: The thiol group of cysteine can be oxidized to form a disulfide bond with the thiol of a second
cysteine, and the resulting linkage holds distant parts of a polypeptide chain together. Methionine
contains sulfur but in a thioether that cannot form this linkage, while proline and histidine have no
sulfur at all. The Portage Learning CHEM 210 module on protein structure and Lehninger Principles of
Biochemistry both present disulfide bond formation as a covalent contribution to tertiary and
quaternary structure, particularly in secreted and extracellular proteins.
Question 9. Which amino acids carry a hydroxyl group on their side chain and can be
phosphorylated by protein kinases?
A. Serine and threonine
B. Alanine and glycine
C. Valine and leucine
D. Phenylalanine and tryptophan
Correct Answer: A
Rationale: Serine and threonine side chains terminate in a primary or secondary alcohol, and the
oxygen of that hydroxyl is a competent nucleophile that protein kinases can attack to form a phosphate
ester. Alanine, glycine, valine, leucine, phenylalanine, and tryptophan carry no hydroxyl group and
cannot be phosphorylated. The Portage Learning CHEM 210 module on post-translational modification
and Berg Biochemistry both present O-linked phosphorylation of serine, threonine, and tyrosine as a
central regulatory device in cell signaling.
CHEM 210 Biochemistry Comprehensive Examination (Modules 1-8) 2026/2027 | Verified Questions
Page 4 of 83
