There are no MCAT past papers in the public domain; the closest thing is the AAMC's own official practice material, available from the AAMC. What is published — in unusual detail — is the content: the four sections, their passage structure and the share of questions from each discipline. The fourteen questions below are drawn from the Myndaq practice bank and are not reproductions of any official item. They cover all four sections, including one passage-based set and one CARS item, each with a worked answer, alongside the Myndaq MCAT course.
The pattern you are practising for
- Chemical and Physical Foundations — 59 questions, 95 minutes; 10 passage sets of 4–6 questions plus 15 independent questions. Disciplines: general chemistry 30%, biochemistry 25%, physics 25%, organic chemistry 15%, biology 5%.
- CARS — 53 questions, 90 minutes; 9 passage sets of 5–7 questions.
- Biological and Biochemical Foundations — 59 questions, 95 minutes. Biology 65%, biochemistry 25%, general and organic chemistry 5% each.
- Psychological, Social, and Biological Foundations — 59 questions, 95 minutes. Psychology 65%, sociology 30%, biology 5%.
- Scoring: 118–132 per section, 472–528 total; wrong answers are scored the same as blanks, so answer everything.
At 95 minutes for 59 questions you have about 1 minute 37 seconds per question, including time to read the passages.
Chemical and Physical Foundations
Question 1 — dilution. A stock solution of 4.0 M HCl is used to prepare 200 mL of 0.50 M HCl. What volume of stock is required?
- A. 12.5 mL
- B. 25 mL
- C. 40 mL
- D. 1600 mL
Answer: B. C₁V₁ = C₂V₂, so V₁ = (0.50 × 200) / 4.0 = 25 mL. Sanity check: the stock is eight times as concentrated, so you need one-eighth of the final volume. D is the ratio inverted; the MCAT expects you to catch that by magnitude alone.
Question 2 — Le Châtelier. The gas-phase equilibrium 2NO(g) + Cl₂(g) ⇌ 2NOCl(g) is exothermic. Which single change will shift the equilibrium towards producing more NOCl?
- A. Removing Cl₂ from the system
- B. Increasing the temperature
- C. Decreasing the container volume at constant temperature
- D. Adding an inert gas at constant volume
Answer: C. Three moles of gas on the left, two on the right; compressing favours fewer moles, so the reaction shifts right. B shifts an exothermic reaction left. D changes no partial pressures, so nothing shifts.
Question 3 — reaction order. For A + B → products, doubling [A] quadruples the rate while doubling [B] leaves the rate unchanged. What is the overall order?
- A. 0
- B. 1
- C. 2
- D. 3
Answer: C. Four = 2², so second order in A; unchanged means zero order in B. Overall 2 + 0 = 2.
Question 4 — average atomic mass. An element X has isotopes X-63 (62.93 amu) and X-65 (64.93 amu); its average atomic mass is 63.55 amu. What is the approximate abundance of X-65?
- A. 31%
- B. 38%
- C. 50%
- D. 69%
Answer: A. Let f be the fraction of X-65: 62.93(1 − f) + 64.93f = 63.55, so 2.00f = 0.62 and f ≈ 0.31. Estimation gets there faster: 63.55 is much closer to 63 than to 65, so the heavier isotope must be the minority. D is the lighter isotope's abundance.
A passage-based set
Passage. Researchers studied the cooling of a small metal sphere to test predictions about heat transfer. A solid copper sphere of mass 0.050 kg was heated to 90 °C and then suspended by a thin insulating thread in a large room held at a constant 20 °C. A fine thermocouple embedded at the centre recorded its temperature every 30 seconds. The specific heat of copper used in the calculations was 385 J per kilogram per degree Celsius.
The investigators observed that the temperature difference between the sphere and the room decreased steadily, with the rate of temperature drop largest at the start and becoming progressively smaller as the sphere approached room temperature. They modelled the cooling as governed by Newton's law of cooling, in which the rate of heat loss is proportional to the temperature difference between the object and its surroundings.
The experiment was repeated with a second copper sphere of identical mass and radius whose surface had been coated with matte black paint. The painted sphere cooled noticeably faster than the bare polished sphere, reaching a lower temperature at every recorded time point. In a third trial, the bare sphere was cooled while a gentle fan directed room-temperature air across its surface; this sphere also cooled faster than the still-air bare sphere. Room temperature never varied by more than 0.2 °C, and the thread contact area was kept minimal to reduce conduction along the support. All spheres were released at the same initial temperature.
Question 5. Why does the rate of temperature drop become progressively smaller as the sphere approaches room temperature?
- A. The thread begins to conduct more heat back into the sphere.
- B. The temperature difference driving heat loss shrinks over time.
- C. The specific heat of copper decreases as the sphere cools.
- D. The mass of the sphere decreases as heat is lost.
Answer: B. The passage gives the model: rate of heat loss is proportional to the temperature difference. As the difference shrinks, so does the rate. MCAT passages frequently state the governing principle; the question checks that you apply it rather than import a guess.
Question 6. The comparison between the matte black sphere and the bare polished sphere most directly tests the influence of which factor on cooling rate?
- A. The surface properties of the sphere
- B. The initial temperature of the sphere
- C. The air movement around the sphere
- D. The mass of the sphere
Answer: A. Identical mass, radius and starting temperature; only the surface differs. C is what the third trial tests. Experimental-design questions reward identifying the one variable that changed between the two conditions named.
Biological and Biochemical Foundations
Question 7 — DNA replication. A eukaryotic cell is treated with a drug that specifically inhibits primase during S phase. With helicase and single-strand binding proteins working normally, which step is most directly blocked?
- A. Sealing the nick between adjacent Okazaki fragments
- B. Initiation of DNA synthesis, because DNA polymerase requires a pre-existing 3′-OH primer
- C. Proofreading by the polymerase's exonuclease activity
- D. Unwinding of the parental duplex
Answer: B. Primase lays down the RNA primer whose 3′-OH DNA polymerase extends; without it, synthesis cannot start. A is ligase, C is polymerase proofreading, D is helicase — and the question told you helicase still works.
Question 8 — renal physiology. A drug blocks the Na⁺-K⁺-2Cl⁻ cotransporter (NKCC2) on the apical membrane of the thick ascending limb. What is the expected effect on urine-concentrating ability?
- A. No change, because the thick ascending limb is water-permeable
- B. Increased water reabsorption in the descending limb
- C. Enhanced medullary hypertonicity and more concentrated urine
- D. Impaired generation of the medullary osmotic gradient, reducing maximal urine concentration
Answer: D. The thick ascending limb pumps NaCl into the interstitium while staying impermeable to water; that is what builds the medullary gradient. Block NKCC2 — as loop diuretics do — and the gradient weakens, so the kidney cannot concentrate urine as fully. A contains a false premise.
Question 9 — population genetics. In a population at Hardy–Weinberg equilibrium, a recessive allele has frequency q = 0.4. What proportion is homozygous dominant?
- A. 0.16
- B. 0.36
- C. 0.48
- D. 0.60
Answer: B. p = 0.6, so p² = 0.36. The wrong options are the other terms of the equation: q² = 0.16, 2pq = 0.48, and p itself.
Question 10 — enzyme kinetics. An enzyme's velocity is 30 μmol/min at [S] = 5 mM and approaches 60 μmol/min at saturating substrate. What is Km?
- A. 2.5 mM
- B. 5 mM
- C. 10 mM
- D. 30 mM
Answer: B. Km is the substrate concentration at half Vmax, and 30 is half of 60, at [S] = 5 mM. No equation needed once you see the half.
Psychological, Social, and Biological Foundations
Question 11 — sensation. A participant can just barely detect a soft tone 50% of the time. The minimum intensity detected half the time is the:
- A. absolute threshold
- B. Weber's constant
- C. difference threshold
- D. just-noticeable difference
Answer: A. The absolute threshold is the minimum intensity detected half the time. C and D concern the smallest detectable change between two stimuli; B is the ratio relating that change to intensity.
Question 12 — group behaviour. Anonymous fans in a large, chaotic crowd engage in destructive behaviour they would never perform alone, having lost their sense of individual identity and accountability. This is best labelled:
- A. social facilitation
- B. deindividuation
- C. conformity
- D. group polarisation
Answer: B. Loss of self-awareness and accountability in a group is deindividuation. Social facilitation concerns performance in front of others; group polarisation is attitudes becoming more extreme through discussion.
Question 13 — personality. A psychologist argues that behaviour is shaped by a continuous, mutual interaction among personal factors, the environment and behaviour itself. This is central to:
- A. Bandura's reciprocal determinism
- B. Eysenck's biological arousal model
- C. Rogers's self-actualisation
- D. Freud's structural model
Answer: A. Three factors each influencing the others is reciprocal determinism, within social-cognitive theory. Psych/Soc questions are largely a matter of mapping a described phenomenon to the right term; flashcards of definitions pay off here more than anywhere else on the test.
Critical Analysis and Reasoning Skills
Passage. For decades, the standard explanation for the sudden collapse of the Classic Maya lowland cities held that drought alone forced the abandonment of the great urban centers. In this view, a series of severe multi-decade dry spells, reconstructed from lake-sediment and cave-deposit records, depleted the reservoirs on which the cities depended, triggering famine and depopulation. Yet this account, however compelling as a physical mechanism, struggles to explain the striking unevenness of the collapse. Cities in the southern lowlands were largely deserted, while several northern centers not only survived but flourished for another two centuries, despite lying in a region that the same climate records show to have been drier, not wetter, than the abandoned south.
I propose that the decisive variable was not rainfall but political architecture. The southern cities were organized around highly centralized divine kingships, in which a single ruler monopolized both religious authority and the administration of water storage and food distribution. When drought struck, the legitimacy of these rulers, staked on their claimed power to guarantee agricultural fertility, collapsed together with the harvests, and no alternative institutions remained to organize collective survival. The northern centers, by contrast, tended toward more distributed councils, in which authority was shared among noble houses and merchant lineages. Such arrangements, I argue, were more resilient precisely because their legitimacy did not rest on any single leader's supernatural guarantee of rain; when one strategy failed, others could be attempted without the entire social order losing its footing.
The drought was thus a common shock that exposed differences already present in how power was arranged. Where authority was concentrated and sacralized, environmental stress became political catastrophe; where it was dispersed and negotiable, the same stress was survivable. To treat climate as the sufficient cause of collapse is to mistake the trigger for the structure it acted upon.
Question 14. A historian reports that the southern lowlands' population before the drought was roughly three times that of the northern centres. For evaluating the author's central argument, this information is best described as:
- A. largely irrelevant, because the argument concerns how authority was structured rather than how many people lived under it
- B. supportive, because it confirms the north was drier than the south
- C. strongly supportive, because larger populations require centralised administration
- D. strongly damaging, because it shows drought affected more people in the south
Answer: A. The author's claim is about political structure. A raw population figure neither shows nor undercuts that structure decided survival. C and D each need an extra premise the passage does not give — that size requires centralisation, or that numbers affected explain collapse. B confuses population with climate. In CARS, the discipline is to judge new information against the argument actually made, not against a better argument you could build from it.
How to use practice like this
Log misses by discipline and weight them by the AAMC's percentages — a gap in biochemistry costs you in two sections at 25% each. For science passages, read for the principle the passage states and the variable each experiment changes. For CARS, keep a daily habit of one timed passage; the skill is pace as much as reading. For the full outline, see the MCAT syllabus and content categories; for a plan, see the MCAT preparation guide.
Quick answers
Are there MCAT previous year papers?
No public past papers exist. The AAMC's own official practice material is the closest equivalent; use it alongside additional practice like this.
Is there negative marking on the MCAT?
No. The AAMC scores wrong answers the same as unanswered questions.
How many questions are passage-based?
In each science section, 10 passage sets of 4–6 questions plus 15 independent questions; CARS is 9 passage sets of 5–7 questions.
How much time do I get per MCAT question?
About 1 minute 37 seconds in each science section (59 questions in 95 minutes) and about 1 minute 42 seconds in CARS (53 in 90).
Which MCAT disciplines carry the most questions?
Introductory biology and biochemistry: biology is 65% of the Biological and Biochemical section, and biochemistry is 25% of both science sections that include it.
