OAT Physics flashcards

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

Cell Theory

All organisms are composed of one or more cells, the cell is the basic unit of structure and function, and new cells arise only from existing cells by division.

Mitosis vs Meiosis

Mitosis yields two identical diploid cells for growth and repair; meiosis yields four genetically distinct haploid gametes through two divisions after a single DNA replication.

Semiconservative Replication

Each new DNA double helix contains one original parental strand and one newly synthesized strand, because helicase unwinds and each template is copied by complementary base pairing.

Codon and Anticodon

A codon is a three-base mRNA sequence specifying an amino acid; the tRNA anticodon is complementary and pairs antiparallel with it at the ribosome during translation.

Competitive Inhibition

An inhibitor binds the enzyme active site and competes with substrate, raising apparent Km while leaving Vmax unchanged because high substrate can outcompete the inhibitor.

Photosynthesis Light Reactions

In thylakoid membranes, light excites photosystems to split water, release oxygen, and produce ATP and NADPH that power carbon fixation in the stroma.

Molarity and Dilution

Molarity is moles of solute per liter of solution; dilution conserves moles, so M1V1 equals M2V2 when solvent is added without additional solute.

Ideal Gas Law

PV equals nRT, where R is 0.0821 L·atm/(mol·K); at STP one mole of ideal gas occupies about 22.4 liters.

Dalton's Law

The total pressure of a gas mixture equals the sum of the partial pressures, and each partial pressure equals its mole fraction times the total pressure.

Henderson-Hasselbalch Equation

pH equals pKa plus the log of conjugate base concentration over weak acid concentration; a buffer resists pH change best within one unit of its pKa.

Le Chatelier's Principle

When a system at equilibrium is disturbed by changes in concentration, pressure, or temperature, the equilibrium shifts in the direction that partially offsets the disturbance.

Gibbs Free Energy

ΔG equals ΔH minus TΔS; a negative ΔG indicates a spontaneous process, and ΔG° equals -RT ln K relating free energy to equilibrium constant.

Electrochemical Cell Potential

E°cell equals E°cathode minus E°anode; a positive value means the reaction is spontaneous, and ΔG° equals -nFE°cell links potential to free energy.

Hybridization Geometry

sp carbons are linear at 180 degrees, sp2 carbons are trigonal planar at 120 degrees, and sp3 carbons are tetrahedral at 109.5 degrees.

SN2 Mechanism

A one-step concerted substitution in which a nucleophile attacks the substrate from the side opposite the leaving group, inverting stereochemistry and favoring primary substrates.

SN1 Mechanism

A two-step substitution in which the leaving group departs first to form a carbocation, which is then attacked by a nucleophile; favors tertiary substrates and polar protic solvents.

Markovnikov's Rule

In addition of HX to an alkene, hydrogen adds to the carbon bearing more hydrogens, generating the more stable carbocation; peroxides reverse this for HBr.

Hückel's Rule

A planar, cyclic, fully conjugated ring is aromatic when it contains 4n+2 pi electrons, such as the six pi electrons of benzene.

Carboxylic Acid Derivative Reactivity

Reactivity toward nucleophilic acyl substitution decreases from acid chloride to anhydride to ester to amide, because leaving-group ability and electron donation differ.

Main Idea Questions

These ask for the passage's overall thesis or purpose; the correct choice must cover the whole passage rather than a single supporting detail.

Inference Questions

These require a conclusion that must follow from the passage; reject choices that are plausible in general but not supported by the stated text.

EXCEPT and NOT Questions

These ask which choice is not supported; the efficient method is eliminating the three choices that the passage explicitly states or clearly implies.

Transition Word Signals

Words like however and yet mark contrast, therefore marks a conclusion, and for example marks illustration; these cues reveal the passage's logical structure.

Successive Percent Change

Percent changes compound multiplicatively rather than additively, so a 20 percent increase followed by a 20 percent decrease produces a net decrease of 4 percent.

Combined Work Rate

Two workers with individual times a and b complete a job together in ab/(a+b) time, because their rates 1/a and 1/b add.

Average Speed Round Trip

Average speed equals total distance divided by total time, so different speeds on each leg give a harmonic-style mean rather than the arithmetic average of speeds.

Combinations vs Permutations

Combinations count unordered selections using n!/(r!(n-r)!); permutations count ordered arrangements using n!/(n-r)!, so order distinguishes the two formulas.

Probability Addition Rule

For two events, the probability of either occurring equals P(A) plus P(B) minus P(A and B), removing the double-counted overlap.

Constant Acceleration Equations

When acceleration is constant, v equals v0 plus at, displacement equals v0t plus half at squared, and v squared equals v0 squared plus 2ax.

Inclined Plane Forces

On a frictionless incline of angle theta, the acceleration down the plane is g sin(theta) and the normal force is mg cos(theta).

Momentum Conservation

Total momentum is conserved in all collisions; elastic collisions also conserve kinetic energy, while perfectly inelastic collisions leave the objects stuck together.

Ohm's Law and Power

Voltage equals current times resistance, and electrical power equals voltage times current or current squared times resistance in a resistive circuit element.

Snell's Law

When light crosses between media, n1 sin(theta1) equals n2 sin(theta2); entering a higher-index medium bends the ray toward the normal.