CHEM 210 Biochemistry Practice Mock Test 2026 2027 with
Real Test Prep Questions with Correct Answers/ Portage Chem
210 Practice Test 2026-2027
Exam
Section 1: Amino Acids & Protein Structure (Q1–20)
Q1. Which amino acid does NOT have a chiral alpha carbon?
A) Alanine
B) Glycine
C) Valine
D) Leucine
Answer: B
Rationale: Glycine has two hydrogen atoms attached to the α-carbon, making it
achiral (no optical activity).
Q2. Which amino acid is a precursor for the neurotransmitter serotonin?
A) Tyrosine
B) Tryptophan
C) Phenylalanine
D) Histidine
Answer: B
Rationale: Tryptophan is hydroxylated to 5-hydroxytryptophan then
decarboxylated to serotonin (5-hydroxytryptamine).
Q3. Which amino acid is a precursor for the neurotransmitters dopamine,
norepinephrine, and epinephrine?
A) Tryptophan
B) Tyrosine
,C) Glutamate
D) Glycine
Answer: B
Rationale: Tyrosine → DOPA → dopamine → norepinephrine → epinephrine
(catecholamines).
Q4. Which amino acid is the primary nitrogen donor for biosynthesis reactions?
A) Glutamate
B) Glutamine
C) Aspartate
D) Alanine
Answer: B
Rationale: Glutamine donates amide nitrogen to purines, pyrimidines, and other
biosynthetic pathways.
Q5. Selenocysteine is considered the 21st amino acid. Which element does it
contain?
A) Sulfur
B) Selenium
C) Iron
D) Zinc
Answer: B
Rationale: Selenocysteine contains selenium instead of sulfur (cysteine analog). It
is co-translationally inserted at UGA codons.
Q6. In a protein, which of the following is NOT a post-translational modification?
A) Phosphorylation
B) Glycosylation
C) Peptide bond formation
D) Acetylation
,Answer: C
Rationale: Peptide bond formation occurs during translation (primary structure),
not post-translationally.
Q7. Protein phosphorylation occurs mainly on which amino acid residues?
A) Alanine, valine, leucine
B) Serine, threonine, tyrosine
C) Aspartic acid, glutamic acid
D) Lysine, arginine
Answer: B
Rationale: Kinases phosphorylate the hydroxyl groups of serine, threonine, and
tyrosine residues.
Q8. Which type of interaction is most important for stabilizing the tertiary
structure of a water-soluble globular protein?
A) Disulfide bonds
B) Hydrogen bonds
C) Hydrophobic effect
D) Ionic bonds
Answer: C
Rationale: The hydrophobic effect (burial of nonpolar side chains away from
water) is the primary driving force for protein folding.
Q9. Prion diseases (e.g., Creutzfeldt-Jakob disease) are caused by:
A) Viral infection
B) Misfolding of the prion protein (PrP) into an aggregated β-sheet-rich form
C) Bacterial toxin
D) Genetic deletion of a chaperone
Answer: B
Rationale: Normal PrP⁰ (α-helical) converts to pathogenic PrPˢᶜ (β-sheet rich),
which aggregates and induces misfolding of other proteins.
, Q10. A protein domain is defined as:
A) The entire primary sequence
B) A locally folded, structurally independent unit within a protein
C) A disulfide bond
D) A membrane-spanning helix
Answer: B
Rationale: Domains are compact, semi-independent folding units that often have
specific functions (e.g., binding domain, catalytic domain).
Q11. The enzyme that hydrolyzes proteins into smaller peptides in the stomach is:
A) Trypsin
B) Chymotrypsin
C) Pepsin
D) Elastase
Answer: C
Rationale: Pepsin is an aspartyl protease activated from pepsinogen by low pH in
the stomach; it cleaves at aromatic amino acids.
Q12. The Michaelis-Menten equation assumes:
A) Allosteric binding
B) Steady-state conditions ([ES] constant)
C) Irreversible inhibition
D) Multiple substrate binding sites
Answer: B
Rationale: The Michaelis-Menten model assumes steady state where the
concentration of the enzyme-substrate complex remains constant over time.
Q13. In enzyme kinetics, a high Kₘ means:
A) High affinity for substrate
Real Test Prep Questions with Correct Answers/ Portage Chem
210 Practice Test 2026-2027
Exam
Section 1: Amino Acids & Protein Structure (Q1–20)
Q1. Which amino acid does NOT have a chiral alpha carbon?
A) Alanine
B) Glycine
C) Valine
D) Leucine
Answer: B
Rationale: Glycine has two hydrogen atoms attached to the α-carbon, making it
achiral (no optical activity).
Q2. Which amino acid is a precursor for the neurotransmitter serotonin?
A) Tyrosine
B) Tryptophan
C) Phenylalanine
D) Histidine
Answer: B
Rationale: Tryptophan is hydroxylated to 5-hydroxytryptophan then
decarboxylated to serotonin (5-hydroxytryptamine).
Q3. Which amino acid is a precursor for the neurotransmitters dopamine,
norepinephrine, and epinephrine?
A) Tryptophan
B) Tyrosine
,C) Glutamate
D) Glycine
Answer: B
Rationale: Tyrosine → DOPA → dopamine → norepinephrine → epinephrine
(catecholamines).
Q4. Which amino acid is the primary nitrogen donor for biosynthesis reactions?
A) Glutamate
B) Glutamine
C) Aspartate
D) Alanine
Answer: B
Rationale: Glutamine donates amide nitrogen to purines, pyrimidines, and other
biosynthetic pathways.
Q5. Selenocysteine is considered the 21st amino acid. Which element does it
contain?
A) Sulfur
B) Selenium
C) Iron
D) Zinc
Answer: B
Rationale: Selenocysteine contains selenium instead of sulfur (cysteine analog). It
is co-translationally inserted at UGA codons.
Q6. In a protein, which of the following is NOT a post-translational modification?
A) Phosphorylation
B) Glycosylation
C) Peptide bond formation
D) Acetylation
,Answer: C
Rationale: Peptide bond formation occurs during translation (primary structure),
not post-translationally.
Q7. Protein phosphorylation occurs mainly on which amino acid residues?
A) Alanine, valine, leucine
B) Serine, threonine, tyrosine
C) Aspartic acid, glutamic acid
D) Lysine, arginine
Answer: B
Rationale: Kinases phosphorylate the hydroxyl groups of serine, threonine, and
tyrosine residues.
Q8. Which type of interaction is most important for stabilizing the tertiary
structure of a water-soluble globular protein?
A) Disulfide bonds
B) Hydrogen bonds
C) Hydrophobic effect
D) Ionic bonds
Answer: C
Rationale: The hydrophobic effect (burial of nonpolar side chains away from
water) is the primary driving force for protein folding.
Q9. Prion diseases (e.g., Creutzfeldt-Jakob disease) are caused by:
A) Viral infection
B) Misfolding of the prion protein (PrP) into an aggregated β-sheet-rich form
C) Bacterial toxin
D) Genetic deletion of a chaperone
Answer: B
Rationale: Normal PrP⁰ (α-helical) converts to pathogenic PrPˢᶜ (β-sheet rich),
which aggregates and induces misfolding of other proteins.
, Q10. A protein domain is defined as:
A) The entire primary sequence
B) A locally folded, structurally independent unit within a protein
C) A disulfide bond
D) A membrane-spanning helix
Answer: B
Rationale: Domains are compact, semi-independent folding units that often have
specific functions (e.g., binding domain, catalytic domain).
Q11. The enzyme that hydrolyzes proteins into smaller peptides in the stomach is:
A) Trypsin
B) Chymotrypsin
C) Pepsin
D) Elastase
Answer: C
Rationale: Pepsin is an aspartyl protease activated from pepsinogen by low pH in
the stomach; it cleaves at aromatic amino acids.
Q12. The Michaelis-Menten equation assumes:
A) Allosteric binding
B) Steady-state conditions ([ES] constant)
C) Irreversible inhibition
D) Multiple substrate binding sites
Answer: B
Rationale: The Michaelis-Menten model assumes steady state where the
concentration of the enzyme-substrate complex remains constant over time.
Q13. In enzyme kinetics, a high Kₘ means:
A) High affinity for substrate
