AAMC MCAT Practice Exam 2 Questions
and Answers | Latest Version | 2024/2025
| 100% Verified
Which of the following best describes the role of enzymes in biochemical reactions?
- A) Enzymes increase the activation energy required for reactions to occur
- B) Enzymes are consumed in the reaction and not regenerated
✔✔ C) Enzymes lower the activation energy required for reactions to occur
- D) Enzymes change the equilibrium constant of a reaction
Rationale: Enzymes act as catalysts by lowering the activation energy required for a biochemical
reaction to proceed, which speeds up the reaction without being consumed or altering the
equilibrium constant.
In a solution, the pH is 4. What is the concentration of hydrogen ions in the solution?
- A) 10⁴ M
- B) 10⁵ M
1
,- C) 10⁻⁴ M
✔✔ D) 10⁻⁴ M
Rationale: The concentration of hydrogen ions in a solution is determined by the formula [H⁺] =
10⁻pH. For a pH of 4, [H⁺] = 10⁻⁴ M.
Which type of bond is primarily responsible for holding together the two strands of a DNA
molecule?
- A) Ionic bonds
✔✔ B) Hydrogen bonds
- C) Covalent bonds
- D) Van der Waals forces
Rationale: Hydrogen bonds are primarily responsible for holding together the complementary
base pairs in the two strands of a DNA molecule.
What is the main function of the ribosome in a cell?
2
,- A) Replication of DNA
✔✔ B) Protein synthesis
- C) ATP production
- D) Lipid synthesis
Rationale: The ribosome is responsible for protein synthesis by translating messenger RNA
(mRNA) into amino acid sequences.
Which of the following is a key difference between prokaryotic and eukaryotic cells?
- A) Prokaryotic cells have a nucleus; eukaryotic cells do not
✔✔ B) Eukaryotic cells have membrane-bound organelles; prokaryotic cells do not
- C) Prokaryotic cells have a cell wall; eukaryotic cells do not
- D) Eukaryotic cells are smaller than prokaryotic cells
Rationale: Eukaryotic cells have membrane-bound organelles, including a nucleus, whereas
prokaryotic cells lack these structures.
During cellular respiration, which molecule is the primary electron carrier?
3
, - A) ATP
✔✔ B) NADH
- C) FADH₂
- D) CO₂
Rationale: NADH is the primary electron carrier in cellular respiration, transferring electrons to
the electron transport chain for ATP production.
What is the primary role of the myelin sheath in neurons?
- A) To increase neurotransmitter release
✔✔ B) To insulate the axon and increase the speed of nerve impulse transmission
- C) To support cellular metabolism
- D) To facilitate synaptic transmission
Rationale: The myelin sheath insulates the axon of neurons and increases the speed of electrical
impulse transmission along the nerve cell.
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and Answers | Latest Version | 2024/2025
| 100% Verified
Which of the following best describes the role of enzymes in biochemical reactions?
- A) Enzymes increase the activation energy required for reactions to occur
- B) Enzymes are consumed in the reaction and not regenerated
✔✔ C) Enzymes lower the activation energy required for reactions to occur
- D) Enzymes change the equilibrium constant of a reaction
Rationale: Enzymes act as catalysts by lowering the activation energy required for a biochemical
reaction to proceed, which speeds up the reaction without being consumed or altering the
equilibrium constant.
In a solution, the pH is 4. What is the concentration of hydrogen ions in the solution?
- A) 10⁴ M
- B) 10⁵ M
1
,- C) 10⁻⁴ M
✔✔ D) 10⁻⁴ M
Rationale: The concentration of hydrogen ions in a solution is determined by the formula [H⁺] =
10⁻pH. For a pH of 4, [H⁺] = 10⁻⁴ M.
Which type of bond is primarily responsible for holding together the two strands of a DNA
molecule?
- A) Ionic bonds
✔✔ B) Hydrogen bonds
- C) Covalent bonds
- D) Van der Waals forces
Rationale: Hydrogen bonds are primarily responsible for holding together the complementary
base pairs in the two strands of a DNA molecule.
What is the main function of the ribosome in a cell?
2
,- A) Replication of DNA
✔✔ B) Protein synthesis
- C) ATP production
- D) Lipid synthesis
Rationale: The ribosome is responsible for protein synthesis by translating messenger RNA
(mRNA) into amino acid sequences.
Which of the following is a key difference between prokaryotic and eukaryotic cells?
- A) Prokaryotic cells have a nucleus; eukaryotic cells do not
✔✔ B) Eukaryotic cells have membrane-bound organelles; prokaryotic cells do not
- C) Prokaryotic cells have a cell wall; eukaryotic cells do not
- D) Eukaryotic cells are smaller than prokaryotic cells
Rationale: Eukaryotic cells have membrane-bound organelles, including a nucleus, whereas
prokaryotic cells lack these structures.
During cellular respiration, which molecule is the primary electron carrier?
3
, - A) ATP
✔✔ B) NADH
- C) FADH₂
- D) CO₂
Rationale: NADH is the primary electron carrier in cellular respiration, transferring electrons to
the electron transport chain for ATP production.
What is the primary role of the myelin sheath in neurons?
- A) To increase neurotransmitter release
✔✔ B) To insulate the axon and increase the speed of nerve impulse transmission
- C) To support cellular metabolism
- D) To facilitate synaptic transmission
Rationale: The myelin sheath insulates the axon of neurons and increases the speed of electrical
impulse transmission along the nerve cell.
4
