MCAT –QUESTIONS AND CORRECT ANSWERS (VERIFIED ANSWERS) PLUS RATIONALES 2026 Q&A | INSTANT
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CORE DOMAINS
Biochemical Principles
Molecular Biology
General Chemistry
Organic Chemistry
Physics and Biological Systems
Psychological and Sociological Foundations of Behavior
Critical Analysis and Reasoning Skills
INTRODUCTION
This practice examination is designed to rigorously evaluate a candidate's readiness for the Medical College
Admission Test. The purpose is to measure the depth of foundational scientific knowledge and the ability to synthesize
information across multiple disciplines. This assessment utilizes a combination of multiple-choice and complex
scenario-based questions to mirror the high-stakes environment of medical school admissions. Candidates are
expected to demonstrate proficiency in applying scientific principles to clinical and experimental contexts. Through an
emphasis on real-world application, ethical decision-making, and analytical reasoning, this exam provides a
comprehensive overview of the skills required for success in a rigorous medical curriculum.
SECTION ONE: QUESTIONS 1–100
1. A patient presents with symptoms of metabolic acidosis. Which of the following blood gas findings is most
consistent with this diagnosis?
A. High pH, low PCO2
B. Low pH, low HCO3-
C. High pH, high HCO3-
D. Low pH, high PCO2
🟢 B. Option
, 🔴 RATIONALE: Metabolic acidosis is characterized by a decrease in pH and a compensatory decrease in
bicarbonate (HCO3-) concentration.
2. Which enzyme is the rate-limiting step in glycolysis?
A. Hexokinase
B. Phosphofructokinase-1
C. Pyruvate kinase
D. Glyceraldehyde-3-phosphate dehydrogenase
🟢 B. Option
🔴 RATIONALE: Phosphofructokinase-1 (PFK-1) catalyzes the conversion of fructose-6-phosphate to fructose-
1,6-bisphosphate, which serves as the primary committed and rate-limiting step in glycolysis.
3. According to the bystander effect, which factor is most likely to increase the probability that an individual will offer
help in an emergency?
A. An increased number of people present
B. A lower degree of ambiguity in the situation
C. A belief that others are more qualified to help
D. Diffusion of responsibility
🟢 B. Option
🔴 RATIONALE: The bystander effect suggests that the likelihood of helping decreases as the number of
witnesses increases due to diffusion of responsibility; reducing ambiguity clarifies the need for intervention.
4. A current of 2.0 A flows through a resistor of 10 ohms. What is the power dissipated by the resistor?
A. 5 W
B. 20 W
C. 40 W
D. 100 W
🟢 C. Option
🔴 RATIONALE: Power is calculated using the formula P = I^2R. Thus, (2.0 A)^2 * 10 ohms = 40 W.
5. In the context of ethical research, what is the primary purpose of an Institutional Review Board (IRB)?
A. To secure funding for clinical trials
, B. To ensure the protection of human subjects
C. To promote the publication of research findings
D. To provide legal defense for principal investigators
🟢 B. Option
🔴 RATIONALE: The fundamental role of the IRB is to review and monitor research involving human subjects to
ensure their rights, welfare, and safety are protected.
6. Which amino acid has a side chain that can act as a buffer at physiological pH?
A. Valine
B. Leucine
C. Histidine
D. Phenylalanine
🟢 C. Option
🔴 RATIONALE: Histidine contains an imidazole side chain with a pKa near 6.0, allowing it to function effectively
as a buffer near physiological pH.
7. Which of the following best describes the function of the myelin sheath in peripheral nerves?
A. To increase the metabolic rate of neurons
B. To facilitate saltatory conduction
C. To prevent the release of neurotransmitters
D. To increase the diameter of the axon
🟢 B. Option
🔴 RATIONALE: Myelin acts as an electrical insulator, allowing action potentials to jump between Nodes of
Ranvier, which significantly increases the speed of nerve impulse transmission.
8. A solution has a [H+] of 1.0 x 10^-5 M. What is the pH of the solution?
A. 4
B. 5
C. 9
D. 10
DOWNLOAD PDF.
CORE DOMAINS
Biochemical Principles
Molecular Biology
General Chemistry
Organic Chemistry
Physics and Biological Systems
Psychological and Sociological Foundations of Behavior
Critical Analysis and Reasoning Skills
INTRODUCTION
This practice examination is designed to rigorously evaluate a candidate's readiness for the Medical College
Admission Test. The purpose is to measure the depth of foundational scientific knowledge and the ability to synthesize
information across multiple disciplines. This assessment utilizes a combination of multiple-choice and complex
scenario-based questions to mirror the high-stakes environment of medical school admissions. Candidates are
expected to demonstrate proficiency in applying scientific principles to clinical and experimental contexts. Through an
emphasis on real-world application, ethical decision-making, and analytical reasoning, this exam provides a
comprehensive overview of the skills required for success in a rigorous medical curriculum.
SECTION ONE: QUESTIONS 1–100
1. A patient presents with symptoms of metabolic acidosis. Which of the following blood gas findings is most
consistent with this diagnosis?
A. High pH, low PCO2
B. Low pH, low HCO3-
C. High pH, high HCO3-
D. Low pH, high PCO2
🟢 B. Option
, 🔴 RATIONALE: Metabolic acidosis is characterized by a decrease in pH and a compensatory decrease in
bicarbonate (HCO3-) concentration.
2. Which enzyme is the rate-limiting step in glycolysis?
A. Hexokinase
B. Phosphofructokinase-1
C. Pyruvate kinase
D. Glyceraldehyde-3-phosphate dehydrogenase
🟢 B. Option
🔴 RATIONALE: Phosphofructokinase-1 (PFK-1) catalyzes the conversion of fructose-6-phosphate to fructose-
1,6-bisphosphate, which serves as the primary committed and rate-limiting step in glycolysis.
3. According to the bystander effect, which factor is most likely to increase the probability that an individual will offer
help in an emergency?
A. An increased number of people present
B. A lower degree of ambiguity in the situation
C. A belief that others are more qualified to help
D. Diffusion of responsibility
🟢 B. Option
🔴 RATIONALE: The bystander effect suggests that the likelihood of helping decreases as the number of
witnesses increases due to diffusion of responsibility; reducing ambiguity clarifies the need for intervention.
4. A current of 2.0 A flows through a resistor of 10 ohms. What is the power dissipated by the resistor?
A. 5 W
B. 20 W
C. 40 W
D. 100 W
🟢 C. Option
🔴 RATIONALE: Power is calculated using the formula P = I^2R. Thus, (2.0 A)^2 * 10 ohms = 40 W.
5. In the context of ethical research, what is the primary purpose of an Institutional Review Board (IRB)?
A. To secure funding for clinical trials
, B. To ensure the protection of human subjects
C. To promote the publication of research findings
D. To provide legal defense for principal investigators
🟢 B. Option
🔴 RATIONALE: The fundamental role of the IRB is to review and monitor research involving human subjects to
ensure their rights, welfare, and safety are protected.
6. Which amino acid has a side chain that can act as a buffer at physiological pH?
A. Valine
B. Leucine
C. Histidine
D. Phenylalanine
🟢 C. Option
🔴 RATIONALE: Histidine contains an imidazole side chain with a pKa near 6.0, allowing it to function effectively
as a buffer near physiological pH.
7. Which of the following best describes the function of the myelin sheath in peripheral nerves?
A. To increase the metabolic rate of neurons
B. To facilitate saltatory conduction
C. To prevent the release of neurotransmitters
D. To increase the diameter of the axon
🟢 B. Option
🔴 RATIONALE: Myelin acts as an electrical insulator, allowing action potentials to jump between Nodes of
Ranvier, which significantly increases the speed of nerve impulse transmission.
8. A solution has a [H+] of 1.0 x 10^-5 M. What is the pH of the solution?
A. 4
B. 5
C. 9
D. 10
