NEET UG flashcards

31 cards. Read the term and the definition here. The deck at the top of this page is optional.

Projectile maximum range angle

For a projectile launched and landing at the same level with fixed speed u, horizontal range R = u²sin2θ/g is greatest at θ = 45°, giving R_max = u²/g.

Centripetal acceleration formula

An object in uniform circular motion has acceleration directed towards the centre of magnitude a = v²/r = ω²r, while its speed and kinetic energy stay constant.

Work-energy theorem

The net work done by all forces on a body equals the change in its kinetic energy, W_net = ½mv² − ½mu²; this holds even when non-conservative forces act.

Moment of inertia of solid sphere

A uniform solid sphere of mass M and radius R has moment of inertia (2/5)MR² about any diameter; a thin spherical shell has (2/3)MR² about a diameter.

Doppler effect for sound

Apparent frequency is f' = f(v ± v_o)/(v ∓ v_s), where v is sound speed in still air; choose upper signs when observer and source approach each other.

Photoelectric stopping potential

Stopping potential V₀ is the retarding voltage that just stops the fastest photoelectrons, so eV₀ = hν − φ, where φ is the work function of the metal.

Radioactive half-life relation

Half-life t½ = 0.693/λ where λ is the decay constant; after n half-lives the fraction of nuclei remaining is (1/2)^n and activity falls by the same factor.

Series LCR resonance frequency

In a series LCR circuit resonance occurs at f = 1/(2π√(LC)); at resonance the reactances cancel, impedance equals R, and current amplitude is maximum.

Ideal gas molar volume

From PV = nRT with R = 8.314 J K⁻¹ mol⁻¹, one mole of an ideal gas occupies 22.4 L at STP (273.15 K, 1 bar/1 atm) and 24.5 L near 298 K.

Buffer pH equation

For an acidic buffer, pH = pKa + log([salt]/[acid]); for a basic buffer, pOH = pKb + log([salt]/[base]); these follow from the Henderson–Hasselbalch treatment.

Gibbs energy and spontaneity

ΔG = ΔH − TΔS determines spontaneity: negative ΔG means spontaneous at constant temperature and pressure, with ΔG° = −RT ln K linking standard free energy to equilibrium constant.

First-order half-life

For a first-order reaction, k = (2.303/t) log(a/(a − x)) and t½ = 0.693/k; the half-life is independent of starting concentration, unlike zero- and second-order reactions.

Nernst equation at 298 K

Cell potential E = E° − (0.0591/n) log Q, where Q is the reaction quotient and n is the number of electrons transferred; E becomes zero at equilibrium when Q = K.

Markovnikov addition rule

When HX adds to an unsymmetrical alkene, the hydrogen attaches to the carbon with more hydrogens, giving the more stable carbocation intermediate; peroxides reverse HBr addition.

SN1 versus SN2 mechanism

SN1 is two-step via a carbocation, first-order, with racemisation; SN2 is one-step backside attack, second-order, with inversion. Tertiary halides favour SN1, primary favour SN2.

Octahedral crystal field splitting

In an octahedral ligand field, d orbitals split into lower t2g and higher eg sets separated by Δ₀; strong-field ligands give low-spin complexes and weak-field ligands high-spin.

Calvin cycle site and enzyme

The Calvin cycle occurs in the chloroplast stroma; RuBisCO fixes CO₂ onto ribulose-1,5-bisphosphate, and ATP and NADPH from light reactions drive reduction to sugar.

C4 photosynthesis advantage

C4 plants fix CO₂ into oxaloacetate in mesophyll cells via PEP carboxylase, then release it in bundle-sheath cells; this concentrates CO₂ around RuBisCO and suppresses photorespiration.

Pressure-flow hypothesis

Phloem translocation follows the Münch pressure-flow model: sugar loading at the source lowers water potential, drawing in water, and unloading at the sink drives bulk flow.

Cohesion-tension theory

Water ascent in xylem is explained by transpiration pull: evaporation at leaves creates tension in continuous water columns held by cohesion and adhesion to vessel walls.

Abscisic acid function

Abscisic acid is a plant stress hormone: it closes stomata during water deficit, promotes seed dormancy and maturation, and inhibits growth and germination under adverse conditions.

Double fertilisation in angiosperms

One male gamete fuses with the egg to form the diploid zygote, while the second fuses with two polar nuclei to form triploid endosperm, a defining feature of angiosperms.

Dihybrid F2 ratio

A Mendelian dihybrid cross of two heterozygotes gives an F₂ phenotypic ratio of 9:3:3:1 when genes assort independently; a test cross of a dihybrid gives 1:1:1:1.

Cardiac output calculation

Cardiac output equals stroke volume multiplied by heart rate; at rest about 70 mL per beat at 72 beats per minute gives roughly 5 litres per minute.

Loop of Henle counter-current

The loop of Henle creates a concentration gradient in the medulla: the descending limb is permeable to water, the ascending limb actively pumps out ions and is water-impermeable.

Carbon dioxide transport forms

About 70% of blood CO₂ travels as bicarbonate after carbonic anhydrase action, roughly 20–23% as carbaminohaemoglobin, and the remainder dissolved in plasma.

Resting membrane potential

The resting potential of a typical neuron is about −70 mV, maintained by the Na⁺/K⁺ ATPase pumping three Na⁺ out for every two K⁺ in, plus K⁺ leak channels.

Insulin and glucagon actions

Insulin from pancreatic β-cells lowers blood glucose by promoting cellular uptake and glycogenesis; glucagon from α-cells raises it by stimulating glycogenolysis and gluconeogenesis.

Rh incompatibility in pregnancy

An Rh-negative mother sensitised by Rh-positive fetal blood can produce anti-Rh antibodies that attack red cells of a later Rh-positive fetus, causing erythroblastosis fetalis.

Semi-conservative DNA replication

Each parental DNA strand acts as a template, so every daughter double helix contains one old and one new strand; Meselson and Stahl demonstrated this using heavy nitrogen labelling.

Digestive enzymes and bile

Pepsin digests proteins in acidic gastric conditions; trypsin and chymotrypsin act in the alkaline small intestine; bile salts emulsify fats but carry no digestive enzymes.