MBBS/BDS Admission cheat sheet

Newton's second law: F_net = ma; on an incline of angle θ, a = g(sinθ − μcosθ) for sliding with kinetic friction μ.

Projectile motion: horizontal velocity constant; time of flight T = 2u sinθ/g; range R = u² sin2θ/g, maximum at θ = 45°.

Circular motion: centripetal acceleration a = v²/r = ω²r; banking angle satisfies tanθ = v²/(rg) with no friction.

Work-energy theorem: W_net = ΔKE; for a spring, elastic potential energy U = ½kx² and F = −kx (Hooke's law).

Momentum: p = mv is conserved in all collisions; kinetic energy is conserved only in perfectly elastic collisions.

Simple harmonic motion: T = 2π√(m/k) for a spring; T = 2π√(L/g) for a small-amplitude pendulum, independent of mass.

Waves: v = fλ; for a string, v = √(T/μ); beats frequency equals the difference of the two source frequencies.

Electricity: Ohm's law V = IR; power P = VI = I²R = V²/R; resistors in series add, in parallel reciprocals add.

Optics and modern physics: Snell's law n₁sinθ₁ = n₂sinθ₂; photoelectric threshold hf₀ = φ, with KEmax = hf − φ.

Mole concept: 1 mol = 6.022×10²³ particles; molarity M = moles of solute per litre of solution; at STP 1 mol gas occupies 22.4 L.

Ideal gas law PV = nRT; combined gas law P₁V₁/T₁ = P₂V₂/T₂; Dalton's law states total pressure is the sum of partial pressures.

Atomic structure: quantum numbers n, l, m_l, m_s; maximum electrons in shell n is 2n²; Aufbau and Hund's rules govern filling.

Periodic trends: atomic radius decreases across a period and increases down a group; ionisation energy and electronegativity follow the opposite trend.

Bonding: ionic bonds form between metals and nonmetals by electron transfer; covalent bonds share electrons; VSEPR predicts shape from electron-pair repulsion.

Acids and bases: pH = −log[H⁺]; for a weak acid, K_a = [H⁺]²/[HA]; buffer pH follows the Henderson–Hasselbalch equation pH = pK_a + log([A⁻]/[HA]).

Le Chatelier's principle: raising temperature favours the endothermic direction; increasing pressure favours the side with fewer gas moles.

Thermochemistry: ΔG = ΔH − TΔS; a reaction is spontaneous when ΔG < 0; ΔH negative is exothermic.

Organic chemistry: alkanes undergo substitution, alkenes addition, alcohols oxidation; functional-group priority determines IUPAC naming.

Photosynthesis: 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂; light reactions occur in thylakoids, the Calvin cycle in the stroma.

Cellular respiration: glycolysis in cytoplasm yields 2 ATP and 2 pyruvate; the Krebs cycle occurs in the mitochondrial matrix; the electron transport chain yields most ATP.

Plant transport: xylem carries water and minerals upward driven by transpiration pull; phloem translocates sugars bidirectionally by pressure flow.

Plant hormones: auxin promotes cell elongation and phototropism; gibberellin promotes stem elongation and seed germination; abscisic acid closes stomata.

Mendelian genetics: monohybrid cross gives a 3:1 phenotype ratio; dihybrid cross gives 9:3:3:1; test cross reveals genotype of a dominant phenotype.

Human circulation: the heart has four chambers; the left ventricle pumps oxygenated blood to the aorta; the SA node sets the heart rhythm.

Nervous system: the resting potential is maintained by the Na⁺/K⁺ pump; the action potential involves Na⁺ influx followed by K⁺ efflux.

Excretion and respiration: the nephron's glomerulus filters blood, tubules reabsorb water and glucose; alveolar gas exchange occurs by simple diffusion.

Classification and ecology: binomial nomenclature uses genus and species; energy transfer between trophic levels is about 10% per level.