MCAT Foundational Concepts

Cards (32)

• 1
  Front

  What is the Henderson-Hasselbalch equation?

  Back

  pH = pKa + log([A-]/[HA]). It relates the pH of a buffer solution to the pKa of the weak acid and the ratio of conjugate base to weak acid concentrations.

• 2
  Front

  What is the difference between competitive and noncompetitive enzyme inhibition?

  Back

  Competitive inhibition increases apparent Km (Vmax unchanged); noncompetitive inhibition decreases Vmax (Km unchanged). Competitive inhibitors bind the active site; noncompetitive inhibitors bind an allosteric site.

• 3
  Front

  What are the products of one turn of the citric acid cycle?

  Back

  3 NADH, 1 FADH2, 1 GTP (or ATP), and 2 CO2 per turn.

• 4
  Front

  What is the net ATP yield of glycolysis (per glucose)?

  Back

  Net 2 ATP, 2 NADH, and 2 pyruvate are produced from one glucose molecule.

• 5
  Front

  What is the law of independent assortment?

  Back

  Genes located on different chromosomes (or far apart on the same chromosome) are inherited independently of one another during gamete formation.

• 6
  Front

  What distinguishes Gram-positive from Gram-negative bacteria?

  Back

  Gram-positive bacteria have a thick peptidoglycan cell wall and stain purple. Gram-negative bacteria have a thin peptidoglycan layer with an outer lipopolysaccharide membrane and stain pink/red.

• 7
  Front

  During which phase of meiosis does crossing over occur?

  Back

  Crossing over occurs during prophase I of meiosis, between non-sister chromatids of homologous chromosomes.

• 8
  Front

  What is the role of the smooth endoplasmic reticulum (SER)?

  Back

  The SER synthesizes lipids and steroids, detoxifies drugs and alcohol, and stores calcium ions, but lacks ribosomes and does not participate in protein synthesis.

• 9
  Front

  What is Michaelis-Menten kinetics and what does Km represent?

  Back

  Michaelis-Menten kinetics describes enzyme reaction rate as a function of substrate concentration. Km is the substrate concentration at which reaction rate is half of Vmax; a lower Km indicates higher enzyme-substrate affinity.

• 10
  Front

  What is the difference between SN1 and SN2 reactions?

  Back

  SN1 is a two-step reaction forming a carbocation intermediate, favored by tertiary substrates and polar protic solvents. SN2 is a one-step concerted reaction with backside attack, favored by primary substrates and polar aprotic solvents, causing inversion of configuration.

• 11
  Front

  What is Hess's Law?

  Back

  The total enthalpy change of a reaction is the sum of enthalpy changes of its individual steps, regardless of the pathway taken.

• 12
  Front

  What is Le Chatelier's Principle?

  Back

  If a stress (change in concentration, pressure, or temperature) is applied to a system at equilibrium, the system shifts in the direction that counteracts that stress to re-establish equilibrium.

• 13
  Front

  What is the relationship between Gibbs free energy, enthalpy, and entropy?

  Back

  ΔG = ΔH - TΔS. A reaction is spontaneous when ΔG < 0.

• 14
  Front

  What is Boyle's Law?

  Back

  At constant temperature, the pressure and volume of a gas are inversely proportional: P1V1 = P2V2.

• 15
  Front

  What is the structure of an amino acid at physiological pH?

  Back

  At physiological pH (~7.4), amino acids exist as zwitterions: the amino group is protonated (-NH3+) and the carboxyl group is deprotonated (-COO-).

• 16
  Front

  What is colligative property and name four examples?

  Back

  Colligative properties depend on the number of solute particles, not their identity. Examples: boiling point elevation, freezing point depression, osmotic pressure, and vapor pressure lowering.

• 17
  Front

  What is Newton's second law of motion?

  Back

  F = ma. The net force on an object equals its mass times its acceleration.

• 18
  Front

  What is Ohm's Law?

  Back

  V = IR. Voltage equals current multiplied by resistance.

• 19
  Front

  What is the work-energy theorem?

  Back

  The net work done on an object equals the change in its kinetic energy: W_net = ΔKE.

• 20
  Front

  What is the difference between longitudinal and transverse waves?

  Back

  In longitudinal waves, particle displacement is parallel to wave propagation (e.g., sound). In transverse waves, displacement is perpendicular to propagation (e.g., light, electromagnetic waves).

• 21
  Front

  What is the law of conservation of energy?

  Back

  Energy cannot be created or destroyed; it can only be converted from one form to another. Total mechanical energy (KE + PE) is conserved in the absence of non-conservative forces.

• 22
  Front

  What is operant conditioning?

  Back

  A learning process in which behavior is shaped by its consequences. Reinforcement increases behavior frequency; punishment decreases it. Associated with B.F. Skinner.

• 23
  Front

  What is the difference between positive and negative reinforcement?

  Back

  Positive reinforcement adds a desirable stimulus to increase behavior. Negative reinforcement removes an aversive stimulus to increase behavior. Both increase the likelihood of the behavior.

• 24
  Front

  What is the fundamental attribution error?

  Back

  The tendency to overemphasize dispositional (internal) factors and underemphasize situational (external) factors when explaining other people's behavior.

• 25
  Front

  What is Erikson's stage of 'Identity vs. Role Confusion'?

  Back

  It occurs during adolescence. The developmental task is forming a coherent sense of personal identity. Failure leads to confusion about one's role in society.

• 26
  Front

  What is the difference between reliability and validity in psychological testing?

  Back

  Reliability is the consistency of a test's results across repeated measurements. Validity is whether the test actually measures what it claims to measure. A test can be reliable without being valid.

• 27
  Front

  What is the action potential threshold?

  Back

  The membrane potential (~-55 mV in neurons) that must be reached to trigger a full, all-or-nothing action potential by opening voltage-gated Na+ channels.

• 28
  Front

  What is the function of the hypothalamus?

  Back

  The hypothalamus regulates homeostasis including body temperature, hunger, thirst, circadian rhythms, and hormone release via control of the pituitary gland.

• 29
  Front

  What is Hardy-Weinberg equilibrium and what are its five conditions?

  Back

  Hardy-Weinberg equilibrium describes a non-evolving population where allele frequencies remain constant. Conditions: no mutation, no gene flow, random mating, large population size, and no natural selection.

• 30
  Front

  What is the role of aldosterone and where is it produced?

  Back

  Aldosterone is a mineralocorticoid produced by the adrenal cortex. It acts on the kidney's collecting duct to increase sodium reabsorption and potassium excretion, raising blood pressure.

• 31
  Front

  What is the difference between primary and secondary active transport?

  Back

  Primary active transport uses ATP directly to move ions against their gradient (e.g., Na+/K+ ATPase). Secondary active transport uses the electrochemical gradient established by primary transport to co-transport another molecule (e.g., SGLT).

• 32
  Front

  What is Snell's Law and what does it describe?

  Back

  Snell's Law (n1 sin θ1 = n2 sin θ2) describes the refraction of light at an interface between two media with different indices of refraction. Light bends toward the normal when entering a denser medium.