MilesDown MCAT Practice Deck

Definitions + Application-style questions

What is an adiabatic process, in thermodynamic terms?

Thermodynamic process in which no heat is exchanged between system and surroundings (Q = 0).

In genetics, what is an allele?

Alternative form of a gene found at the same locus on homologous chromosomes.

In organic chemistry, what chemical group is formed when the –OH of a carboxylic acid is replaced by an amino group?

Carboxylic-acid derivative in which the –OH is replaced by an amino group; named with the suffix –amide.

Which limbic-system structure is primarily involved in emotional processing, especially fear and aggression?

Limbic-system structure involved in emotional processing, especially fear and aggression.

In an electrochemical cell diagram, which electrode is where oxidation occurs?

Anode

If you observe a Y-shaped protein that specifically binds antigens, what is it and which cells produce it?

Antibodies; produced by plasma cells to neutralize pathogens or mark them for destruction.

Looking at a cyclic, planar molecule, what property indicates unusual stability due to (4n + 2) \pi electrons?

Aromaticity

A biological diagram illustrates ATP synthesis. What enzyme is critical for this process, utilizing a proton gradient?

ATP Synthase

What hormone, released by atrial cells due to stretch, decreases blood pressure by promoting Na⁺ and water excretion?

ANP

What is the numerical value for Avogadro’s Number (Nₐ) and what does it represent?

6.022 \times 10^{23} particles per mole; converts between number of entities and amount of substance.

Observe a nuclear reaction diagram. What type of decay involves a neutron converting to a proton or vice versa, emitting an electron or positron?

Beta Decay

1. Beta-minus (β⁻) decay:

   • A neutron converts into a proton.

   • Emits an electron (β⁻) and an antineutrino (ν̄ₑ).

   • Common in neutron-rich nuclei.

2. Beta-plus (β⁺) decay (also called positron emission):

   • A proton converts into a neutron.

   • Emits a positron (β⁺) and a neutrino (νₑ).

   • Common in proton-rich nuclei.

Consider a simple atomic model showing electrons in fixed orbits with energy increasing with distance from the nucleus (E = -R_h/n^2). Which early atomic model is this?

Bohr Model

Which gas law states that at constant temperature, the pressure of a gas is inversely proportional to its volume (PV = \text{constant})?

Boyle’s Law (PV = \text{constant}), (P=1/V)

What type of solution, composed of a weak acid/base and its conjugate, resists changes in pH within \pm1 of its pK_a?

Buffer Solution

What substance increases reaction rate by lowering activation energy without being consumed?

Enzyme

What net force is required for uniform circular motion, directed toward the center (F = mv^2/r)?

Centripetal Force

What is the fundamental property, measured in coulombs (C), where protons carry +e and electrons -e (e = 1.60 \times 10^{-19} C)?

Electric Charge

According to Charles’s Law, how is the volume of a gas related to its temperature in kelvin at constant pressure?

(V = T); (V1/T1 = V2/T2)

In a cell morphology diagram, what DNA-protein complex forms chromosomes and exists as dense heterochromatin or loose euchromatin?

Chromatin

Which type of enzyme inhibitor binds to the active site, increasing Km but leaving V{max} unchanged, and can be overcome with substrate?

Competitive Inhibitor

What group of serum proteins punches holes in bacterial cell walls and enhances opsonization as part of the immune system?

Complement System

When atoms of similar electronegativity share electrons, what type of chemical bond is formed?

Nonpolar Covalent Bond

What genetic process, depicted in a meiosis diagram, involves the exchange of genetic material between homologous chromosomes during prophase I to increase diversity?

Genetic Recombination

What is the decrease in amplitude of an oscillating system due to non-conservative forces like friction?

Damping

According to Dalton’s Law, what is the total pressure of a gas mixture?

Total pressure of a gas mixture equals sum of partial pressures; each partial pressure equals mole fraction times total pressure.

What is mass per unit volume (\rho), and what are its values for water?

Density; \rho = m/V; for water, 1 \text{ g cm}^{-3} = 1000 \text{ kg m}^{-3}.

An action potential graph shows a rapid rise. What term describes this decrease in membrane potential (more positive) due to Na⁺ influx?

Depolarization

Identify the cell junction in an epithelial tissue diagram that anchors cytoskeletons to resist mechanical stress.

Desmosome

Which sociological theory posits that deviance is learned through interaction with others who violate norms?

Differential Association Theory

What intermolecular attraction occurs between permanent partial charges of polar molecules?

Dipole-dipole Interaction

In a protein structure diagram, what covalent linkage is often seen stabilizing tertiary or quaternary structures, specifically between two cysteine residues (-\text{S}-\text{S}-)?

Disulfide Bonds

A replication fork diagram shows fragments being joined. Which enzyme is responsible for sealing nicks and joining Okazaki fragments in the DNA backbone by forming phosphodiester bonds?

DNA Ligase

What is an atom’s tendency to attract electrons in a bond, which increases up and to the right on the periodic table?

Electronegativity

What thermodynamic measure of disorder or energy dispersal is maximized at equilibrium?

Entropy (delta S)

What is a biological catalyst, usually a protein, that increases reaction rate by lowering activation energy with high specificity?

Enzyme

What is the Equilibrium Constant (K_{eq})?

Ratio of product to reactant activities at equilibrium; temperature dependent, excludes solids and liquids.

What is the value of the Faraday Constant (F) and what does it represent?

96\ 485 \text{ C mol}^{-1}; charge of one mole of electrons.

According to Fick’s Law, how is the rate of diffusion proportional?

Rate of diffusion proportional to area and concentration gradient, inversely proportional to distance.

What type of mutation results from an insertion or deletion not in multiples of three nucleotides, altering the downstream reading frame of mRNA?

Frameshift Mutation

A signal transduction pathway diagram presents a membrane receptor associated with a heterotrimeric G protein that activates second-messenger cascades upon ligand binding. What type of receptor is illustrated?

GPCR (G-Protein Coupled Receptors)

Identify the metabolic pathway, typically depicted in liver functions, that generates glucose from non-carbohydrate precursors (lactate, glycerol, amino acids).

Metabolic pathway generating glucose from non-carbohydrate precursors (lactate, glycerol, amino acids) mainly in liver.

A carbohydrate storage diagram depicts a highly branched polysaccharide storage form of glucose in animals, connected by \alpha-1,4 and \alpha-1,6 glycosidic bonds. What is this molecule?

Glycogen

What ideal population condition dictates that allele and genotype frequencies remain constant, requiring no mutation, migration, selection, infinite size, and random mating?

Hardy-Weinberg Principle

What is the energy required to convert one gram or mole of liquid to gas at constant temperature?

Heat of Vaporization

1g water at its boiling point (100°C) = 2,260 J

1 mole water = 40.7 kJ

Examine the structure of a tetrameric protein in red blood cells. What is this oxygen-transporting molecule, known for cooperative binding of O₂ and transport of CO₂?

Hemoglobin

What equation relates pH to pK_a and the ratio of conjugate base to acid?

Henderson-Hasselbach Equation

pH = pKa + log([conjugate base]/[acid])

What signaling molecule is secreted into the bloodstream to regulate the physiology and behavior of distant organs?

Hormones

In an orbital diagram, what process describes the mixing of atomic orbitals to form equivalent hybrid orbitals in covalent bonding?

Hybridization

What law relates pressure, volume, moles, and temperature of an ideal gas (PV = nRT)?

Ideal Gas Law

In chemistry, what are the electron-withdrawing or -donating effects transmitted through sigma bonds due to electronegativity differences?

Inductive Effect

What refers to the non-specific first-line defense mechanisms present at birth, including barriers, phagocytes, complement, and interferons?

Innate Immunity

What is the pH at which a molecule (often a protein) carries no net charge?

Isoelectric Point (pI)

What are atoms of the same element with equal protons but different neutrons and therefore different mass numbers?

Isotopes

What is K_{cat}?

Turnover number; number of substrate molecules converted to product per enzyme per second under saturated conditions.

What metabolic pathway, active during prolonged fasting, leads to the formation of ketone bodies (acetoacetate, \beta-hydroxybutyrate, acetone) from acetyl-CoA?

Ketogenesis

What rule states that the sum of voltage sources equals the sum of voltage drops around any closed circuit loop?

Kirchhoff’s Voltage Law

What is the anaerobic reduction of pyruvate to lactate, regenerating NAD⁺ for glycolysis?

Lactic Acid Fermentation

A fluid dynamics diagram shows smooth, orderly fluid motion characterized by parallel layers with no disruption between them. What kind of flow is this, described by Poiseuille’s law?

Laminar Flow

What principle states that a system at equilibrium counteracts applied stresses (concentration, pressure, temperature) to re-establish equilibrium?

Le Chatelier’s Principle

What is the non-random association of alleles at different loci in a population?

Linkage Disequilibrium

What quantum number defines orbital orientation, being an integer between -l and +l?

Magnetic Quantum Number (ml)

What is the Michaelis–Menten Constant (K_m)?

Substrate concentration at which enzyme velocity is half of V_{max}; indicator of affinity.

Identify the lipid-rich sheath in a neuron diagram that insulates axons, produced by Schwann cells (PNS) or oligodendrocytes (CNS), increasing conduction velocity.

Myelin Sheath

What equation relates the reduction potential of a half-cell to standard potential, temperature, activity, and reaction quotient?

Nernst Equation

E = E^\circ - \frac{RT}{nF}\ln Q.

What is an electron-rich species that donates an electron pair to form a new covalent bond, also known as a Lewis base?

Nucleophile

What law states that the voltage across a conductor equals current times resistance (V = IR)?

Ohm’s Law

In a prokaryotic gene regulation diagram, what genetic unit is a cluster of genes transcribed as a single mRNA and regulated by a common operator, promoter, and regulatory genes?

Operon

Described by a detailed biochemical pathway, what process involves ATP synthesis powered by an electron transport chain-generated proton gradient across the inner mitochondrial membrane?

ATP synthesis powered by electron transport chain-generated proton gradient across inner mitochondrial membrane.

What term describes an atom or molecule with unpaired electrons that is attracted into an external magnetic field?

Atom or molecule with unpaired electrons that is attracted into an external magnetic field.

In a protein synthesis diagram, what type of amide linkage forms between \alpha-carboxyl and \alpha-amino groups, formed via dehydration?

Peptide bond

What is the pI (Isoelectric Point)?

The pH at which a molecule’s net charge is zero; determined by averaging pK_a values bordering the neutral form.

Referring to a diagram of laminar fluid flow in a pipe, which law describes the flow rate (Q) as \frac{\pi r^4 \Delta P}{8\eta L}?

Describes laminar flow rate of incompressible fluid in a pipe; Q = \frac{\pi r^4 \Delta P}{8\eta L}.

What is the rate of energy transfer or work done per unit time (P = W/t), with SI unit watt (W)?

Rate of energy transfer or work done per unit time (P = W/t); SI unit watt (W).

Identify the nitrogenous base with a two-ring structure from a nucleic acid base diagram.

Nitrogenous base with two-ring structure; adenine and guanine.

What is the ratio of the speed of light in vacuum to that in a medium, determining the bending of light (Snell’s law)?

Ratio of speed of light in vacuum to that in a medium; determines bending of light (Snell’s law).

What bacterial endonuclease cleaves DNA at specific recognition sequences and is used in molecular cloning?

Bacterial endonuclease that cleaves DNA at specific recognition sequences; used in molecular cloning.

In a galvanic cell diagram, what ion-containing pathway completes the circuit and maintains charge neutrality by allowing ion flow?

Ion-containing pathway that completes the circuit and maintains charge neutrality by allowing ion flow.

In a muscle fiber diagram, what is the basic contractile unit of striated muscle bounded by Z-lines, containing actin (thin) and myosin (thick) filaments?

Sarcomere

What is the fundamental quantum-mechanical equation describing electron wavefunction and energy states?

Fundamental quantum-mechanical equation describing electron wavefunction and energy states.

What law states that the total entropy of an isolated system can never decrease, indicating that energy spontaneously disperses?

Total entropy of an isolated system can never decrease; energy spontaneously disperses.

Illustrated in a molecular orbital diagram, what type of covalent bond is formed by head-to-head or end-to-end orbital overlap, allowing free rotation?

Covalent bond formed by head-to-head or end-to-end orbital overlap, allowing free rotation.

A reaction mechanism diagram shows a two-step nucleophilic substitution via a carbocation intermediate. What type of reaction is this, whose rate depends only on substrate concentration?

Two-step nucleophilic substitution via carbocation intermediate; rate depends only on substrate concentration.

A reaction mechanism diagram shows a one-step bimolecular nucleophilic substitution with backside attack. What type of reaction is this, whose rate depends on both substrate and nucleophile, and inverts stereochemistry?

One-step bimolecular nucleophilic substitution with backside attack; rate depends on substrate and nucleophile and inverts stereochemistry.

What is the heat energy required to raise one gram of a substance by 1 \text{ } ^\circ \text{C} (q = mc\Delta T)?

Heat energy required to raise one gram of a substance by 1 \text{ } ^\circ \text{C} (q = mc\Delta T).

What is the tendency of a species to gain electrons measured versus a standard hydrogen electrode under standard conditions?

Tendency of a species to gain electrons measured versus standard hydrogen electrode under standard conditions.

What is the difference in wavelength between absorbed and emitted photons in fluorescence?

Difference in wavelength between absorbed and emitted photons in fluorescence.

In an alveolar structure diagram, what amphipathic molecule reduces surface tension in alveoli, preventing collapse during exhalation?

Amphipathic molecule reducing surface tension in alveoli, preventing collapse during exhalation.

A chemical isomer diagram shows reversible interconversion of structural isomers differing in proton and double-bond position, e.g., keto–enol. What is this process?

Reversible interconversion of structural isomers differing in proton and double-bond position, e.g., keto–enol.

What analytical technique involves adding a solution of known concentration (titrant) to determine the concentration of another (analyte)?

Analytical technique in which a solution of known concentration (titrant) is added to determine concentration of another (analyte).

What is rotational force, equal to rF \sin \theta, that causes angular acceleration around a pivot?

Rotational force equal to rF \sin \theta; causes angular acceleration around a pivot.

What are the weak intermolecular attractions including London dispersion, dipole–dipole, and dipole-induced interactions?

Weak intermolecular attractions including London dispersion, dipole–dipole, and dipole-induced interactions.

Observe a fluid flowing through a constricted pipe. What effect explains the reduction in fluid pressure in the constricted section, explained by Bernoulli’s principle?

Reduction in fluid pressure when flowing through a constricted section, explained by Bernoulli’s principle.

What mathematical function describes quantum-state probability amplitude, where |\psi|^2 gives probability density?

Mathematical function describing quantum-state probability amplitude; |\psi|^2 gives probability density.

In an amino acid diagram, what term describes a molecule with equal positive and negative charges but is overall neutral at physiological pH?

Molecule with equal positive and negative charges but overall neutral, common in amino acids at physiological pH.

A patient with damage to a specific region of their limbic system exhibits an unusual lack of fear response and reduced aggressive behavior. Brain imaging studies highlight an affected almond-shaped structure. Which limbic-system structure is most likely damaged?

Limbic-system structure involved in emotional processing, especially fear and aggression.

Referring to an electrochemical cell diagram, if the cell is operating as a galvanic cell, which electrode will be the site of oxidation, and what sign will it carry? Conversely, if it is an electrolytic cell, will this electrode be positive or negative?

Electrochemical-cell electrode where oxidation occurs; negative in galvanic cells, positive in electrolytic cells.

A lab technician examines a patient's blood sample and observes numerous Y-shaped proteins that are highly effective at neutralizing specific viral particles by binding to their surface. These proteins are crucial components of adaptive immunity. What are these proteins, and which specialized immune cells are responsible for their synthesis and secretion?

Y-shaped protein that specifically binds antigens; produced by plasma cells to neutralize pathogens or mark them for destruction.

A molecular structure diagram displays a cyclic, planar molecule with a fully conjugated system containing 6 pi electrons. This particular electron count confers exceptional stability, making the molecule resistant to certain reactions. What specific property is responsible for this unusual stability and follows the (4n + 2) \pi rule?

Property of cyclic, planar molecules with (4n + 2) \pi electrons that leads to unusual stability; exemplified by benzene.

Examining a diagram of the inner mitochondrial membrane, an enzyme complex is shown spanning the membrane, actively synthesizing ATP. This enzyme harnesses the energy from a proton (H⁺) gradient, moving protons from the intermembrane space back into the mitochondrial matrix. What is this critical enzyme?

Mitochondrial membrane enzyme that uses the proton-motive force to convert ADP and Pi into ATP during oxidative phosphorylation.

A patient experiencing volume overload has elevated blood pressure. In response, their heart's atrial cells release a hormone that acts on the kidneys to increase sodium and water excretion, thereby reducing blood volume and pressure. What is this hormone?

Atrial Natriuretic Peptide (ANP)