BSSE General Science 1430 cheat sheet

Scientific method: observation, question, hypothesis, experiment, data analysis, conclusion, communication; hypotheses must be testable and falsifiable.

Independent variable is manipulated; dependent variable is measured; controlled variables are held constant to isolate cause and effect.

Accuracy is closeness to true value; precision is closeness of repeated measurements to each other; random errors affect precision, systematic errors affect accuracy.

SI base units: length meter (m), mass kilogram (kg), time second (s), temperature kelvin (K), amount mole (mol), electric current ampere (A), luminous intensity candela (cd).

Metric prefixes: kilo (10^3), centi (10^-2), milli (10^-3), micro (10^-6), nano (10^-9); convert by moving decimal or multiplying by power of ten.

Significant figures: all nonzero digits count; zeros between nonzero digits count; leading zeros do not count; trailing zeros after a decimal point count; multiplication/division result keeps least number of sig figs, addition/subtraction keeps least decimal places.

Density = mass/volume; percent error = |experimental - accepted| / accepted × 100%; scientific notation expresses numbers as a × 10^n where 1 ≤ a < 10.

A scientific theory is a well-tested explanation supported by evidence; a law describes a consistent relationship; both are subject to revision with new evidence.

Correlation does not imply causation; controlled experiments with randomization and blinding reduce bias; peer review and replication strengthen claims.

Matter is anything with mass and volume; pure substances (elements, compounds) have fixed composition; mixtures (homogeneous, heterogeneous) do not.

Atomic number Z = protons; mass number A = protons + neutrons; isotopes have same Z but different A; ions form by gaining or losing electrons.

Electron configuration follows Aufbau principle, Pauli exclusion principle, and Hund's rule; valence electrons determine chemical properties and group number for main-group elements.

Periodic trends: atomic radius decreases left to right and increases top to bottom; ionization energy and electronegativity increase left to right and decrease top to bottom.

Chemical reactions conserve mass and atoms; balance equations by adjusting coefficients, never subscripts; types include synthesis, decomposition, single replacement, double replacement, combustion.

Mole concept: 1 mol = 6.022 × 10^23 particles; molar mass in g/mol; moles = mass/molar mass; stoichiometry uses mole ratios from balanced equations.

Acids donate H+ (proton) and bases accept H+; pH = -log[H+]; pH < 7 acidic, pH = 7 neutral, pH > 7 basic; strong acids/bases dissociate completely.

Bonding: ionic bonds transfer electrons between metals and nonmetals; covalent bonds share electrons between nonmetals; metallic bonds involve delocalized electrons.

Conservation of energy in reactions: exothermic releases heat (ΔH < 0), endothermic absorbs heat (ΔH > 0); activation energy is the minimum energy for reaction.

Newton's laws: (1) inertia-objects resist changes in motion; (2) F_net = ma; (3) every action has an equal and opposite reaction.

Kinematics: v = v0 + at; Δx = v0t + ½at²; v² = v0² + 2aΔx; average speed = distance/time; velocity includes direction.

Weight = mg (g ≈ 9.8 m/s² on Earth); friction opposes motion and depends on normal force and surfaces; net force determines acceleration.

Work = Fd cosθ; kinetic energy KE = ½mv²; gravitational potential energy PE = mgh; power = work/time; conservation of mechanical energy when only conservative forces act.

Momentum p = mv; impulse = FΔt = Δp; in isolated systems total momentum is conserved in collisions (elastic: KE conserved; inelastic: KE not conserved).

Wave properties: wavelength λ, frequency f, period T = 1/f, amplitude, speed v = fλ; transverse waves oscillate perpendicular to travel, longitudinal waves parallel.

Sound requires a medium; speed depends on medium (fastest in solids); pitch relates to frequency, loudness to amplitude; Doppler effect is frequency shift due to relative motion.

Light behaves as wave and particle; reflection angle equals incidence angle; refraction bends light when speed changes (Snell's law); electromagnetic spectrum ordered by wavelength/frequency.

Electric charge is quantized (e = 1.6 × 10^-19 C); like charges repel, opposite attract; Coulomb's law F = kq1q2/r².

Ohm's law V = IR; electric power P = IV = I²R = V²/R; series circuits share current and sum resistance; parallel circuits share voltage and sum currents as 1/R_total = Σ1/R_i.

Electric current is flow of charge (I = Q/t); voltage is potential difference driving current; conductors allow charge flow, insulators resist it.

Magnetic fields arise from moving charges and permanent magnets; field lines run from north to south outside a magnet; like poles repel, opposite poles attract.

Electromagnetic induction: changing magnetic flux through a conductor induces voltage (Faraday's law); generators convert mechanical energy to electrical energy.

Wave-particle duality: light exhibits interference and diffraction (wave) and photoelectric effect (particle); photoelectric effect depends on frequency, not intensity.

Atomic spectra: emission lines occur when electrons drop to lower energy levels; absorption lines occur when electrons absorb specific photon energies.

Radioactive decay types: alpha (helium nucleus), beta (electron or positron), gamma (high-energy photon); half-life is time for half of a sample to decay.

Nuclear fission splits heavy nuclei releasing energy; fusion combines light nuclei; E = mc² relates mass defect to released energy.

Earth's layers: crust (thin, rocky), mantle (silicate rock, convection), outer core (liquid iron-nickel, generates magnetic field), inner core (solid iron-nickel).

Plate tectonics: lithospheric plates move on asthenosphere; divergent boundaries create new crust (mid-ocean ridges, rift valleys); convergent boundaries cause subduction, mountains, volcanoes; transform boundaries cause earthquakes.

Rock types: igneous forms from cooling magma/lava; sedimentary forms from compaction and cementation of sediments; metamorphic forms from heat and pressure altering existing rock.

Rock cycle links igneous, sedimentary, and metamorphic rocks through melting, weathering, erosion, deposition, and metamorphism.

Earthquakes occur at faults where stress releases energy; focus is underground origin, epicenter is surface point above; seismographs record P waves (fast, longitudinal) and S waves (slower, transverse).

Volcanoes form at subduction zones, mid-ocean ridges, and hotspots; magma composition affects eruption style (high silica = explosive, low silica = fluid).

Weathering breaks rock (mechanical, chemical); erosion transports sediment; deposition lays it down; these processes shape landforms over time.

Relative dating uses superposition (older layers below), cross-cutting relationships, and index fossils; absolute dating uses radioactive isotopes such as carbon-14 and potassium-argon.

Atmosphere layers: troposphere (weather, temperature decreases with altitude), stratosphere (ozone layer, temperature increases), mesosphere, thermosphere, exosphere.

Air pressure decreases with altitude; wind flows from high pressure to low pressure; Coriolis effect deflects moving air right in Northern Hemisphere and left in Southern Hemisphere.

Temperature, pressure, humidity, and wind determine weather; relative humidity is amount of water vapor relative to saturation; dew point is temperature at which air saturates.

Clouds form when rising moist air cools and water vapor condenses on condensation nuclei; types include cumulus, stratus, cirrus, and nimbus (precipitation).

Air masses classified by source region (continental/maritime, polar/tropical); fronts form where air masses meet: cold front (steep, short storms), warm front (gentle, long precipitation), stationary, occluded.

Greenhouse effect: atmospheric gases (CO2, H2O, CH4) absorb and re-emit infrared radiation, warming Earth's surface; enhanced greenhouse effect drives climate change.

Climate vs weather: climate is long-term average conditions; factors include latitude, altitude, ocean currents, proximity to water, and prevailing winds.

Severe weather: thunderstorms require instability and moisture; tornadoes form in severe thunderstorms; hurricanes form over warm ocean water and lose strength over land.

Solar system order from Sun: Mercury, Venus, Earth, Mars (terrestrial), Jupiter, Saturn, Uranus, Neptune (gas/ice giants); asteroid belt between Mars and Jupiter.

Kepler's laws: orbits are ellipses with Sun at one focus; planets sweep equal areas in equal times; orbital period squared is proportional to semi-major axis cubed (T² ∝ a³).

Gravity governs orbits; Newton's law of universal gravitation F = Gm1m2/r²; escape velocity depends on mass and radius of body.

Earth's rotation causes day/night; revolution and axial tilt (23.5°) cause seasons; Moon phases result from changing Sun-Earth-Moon angles; eclipses occur at new (solar) and full (lunar) moon when aligned.

Sun is a main-sequence star powered by nuclear fusion of hydrogen to helium; energy travels by radiation and convection; sunspots and solar flares are magnetic activity.

Stars are classified by spectral type OBAFGKM (hot to cool) and luminosity; Hertzsprung-Russell diagram plots luminosity vs temperature; main sequence stars fuse hydrogen.

Stellar evolution: nebula → protostar → main sequence → red giant/supergiant → white dwarf (low mass) or supernova/neutron star/black hole (high mass).

Galaxies: spiral, elliptical, irregular; Milky Way is a spiral galaxy; universe expansion evidenced by redshift and cosmic microwave background; Big Bang theory describes origin ~13.8 billion years ago.

Light-year is distance light travels in one year (~9.46 × 10^12 km); astronomical unit (AU) is average Earth-Sun distance (~1.5 × 10^8 km).

Cell theory: all living things made of cells; cells are basic unit of life; cells arise from existing cells. Prokaryotes lack nucleus; eukaryotes have membrane-bound organelles.

Organelles: nucleus (DNA control), ribosomes (protein synthesis), mitochondria (ATP production), chloroplasts (photosynthesis), endoplasmic reticulum (transport), Golgi apparatus (packaging), lysosomes (digestion), cell membrane (selective barrier).

Photosynthesis: 6CO2 + 6H2O + light → C6H12O6 + 6O2 in chloroplasts; cellular respiration: C6H12O6 + 6O2 → 6CO2 + 6H2O + ATP in mitochondria.

Cell division: mitosis produces identical diploid cells for growth and repair; meiosis produces haploid gametes with genetic variation through crossing over and independent assortment.

DNA structure: double helix with sugar-phosphate backbone and complementary base pairs A-T, C-G; DNA replicates semiconservatively; genes code for proteins via transcription and translation.

Mendelian genetics: dominant and recessive alleles; genotype vs phenotype; Punnett squares predict offspring ratios; law of segregation and law of independent assortment.

Mutations are changes in DNA sequence; can be harmful, beneficial, or neutral; sources include replication errors and mutagens; variation is raw material for evolution.

Evolution by natural selection: variation exists, more offspring produced than survive, individuals with advantageous traits reproduce more, traits become more common over generations.

Evidence for evolution: fossil record, comparative anatomy (homologous structures), embryology, molecular biology (DNA similarities), and observed adaptation.

Levels of organization: cells → tissues → organs → organ systems → organism; four tissue types: epithelial, connective, muscle, nervous.

Circulatory system: heart pumps blood through arteries, veins, capillaries; blood carries oxygen, nutrients, hormones, wastes; red blood cells contain hemoglobin for O2 transport.

Respiratory system: nose, trachea, bronchi, lungs, alveoli; gas exchange occurs in alveoli by diffusion; diaphragm contracts during inhalation.

Digestive system: mechanical and chemical breakdown; enzymes (amylase, protease, lipase) catalyze hydrolysis; nutrients absorbed in small intestine; water reabsorbed in large intestine.

Nervous system: neurons transmit electrical impulses; central nervous system (brain, spinal cord) and peripheral nervous system; reflex arcs bypass brain for quick response.

Endocrine system: glands secrete hormones into blood; insulin lowers blood glucose, glucagon raises it; negative feedback maintains homeostasis.

Immune system: innate defenses (skin, mucus, inflammation) and adaptive immunity (B cells produce antibodies, T cells destroy infected cells); vaccines stimulate immunity.

Skeletal and muscular systems: bones support and protect, muscles contract to move bones; antagonistic muscle pairs (biceps/triceps) produce movement.

Health: balanced diet, exercise, sleep, hygiene, and avoiding harmful substances support homeostasis; pathogens cause infectious disease; noninfectious diseases include genetic and lifestyle conditions.

Levels of ecology: organism, population, community, ecosystem, biome, biosphere; habitat is where an organism lives, niche is its role.

Energy flow: sunlight → producers (photosynthesis) → consumers (herbivores, carnivores, omnivores) → decomposers; only about 10% of energy transfers between trophic levels; food webs show interconnected chains.

Biogeochemical cycles: carbon (photosynthesis, respiration, combustion, decomposition), nitrogen (fixation, nitrification, denitrification), water (evaporation, condensation, precipitation, runoff), phosphorus (rock weathering, uptake, decomposition).

Population growth: exponential when resources unlimited; logistic when carrying capacity limits growth; limiting factors include food, water, space, disease, predation.

Symbiosis: mutualism (both benefit), commensalism (one benefits, other unaffected), parasitism (one benefits, other harmed); competition occurs when organisms need same resources.

Biodiversity includes genetic, species, and ecosystem diversity; threats include habitat loss, invasive species, pollution, overharvesting, climate change.

Natural resources: renewable (solar, wind, water, biomass) replenish naturally; nonrenewable (fossil fuels, minerals) are finite; conservation and efficiency reduce depletion.

Human impact: pollution, deforestation, greenhouse gas emissions, and urbanization alter ecosystems; sustainability meets present needs without compromising future generations.

Succession: primary succession starts on bare rock (lichens, mosses); secondary succession follows disturbance where soil remains; climax community is stable end stage.