Praxis 5005 cheat sheet

Earth's layers from surface inward: crust, mantle, outer core (liquid), inner core (solid); density and temperature increase with depth.

Plate boundaries: divergent boundaries create new crust, convergent boundaries destroy or crumple crust, transform boundaries slide past one another.

Rock cycle: igneous rock forms from cooling magma or lava; sedimentary rock forms by compaction and cementation; metamorphic rock forms under heat and pressure.

Weathering breaks rock in place; erosion transports weathered material by water, wind, ice, or gravity.

Water cycle: evaporation and transpiration add vapor; condensation forms clouds; precipitation returns water; runoff and infiltration move water across and into land.

Earth's rotation on its axis causes day and night (about 24 hours); revolution around the Sun causes a year (about 365.25 days).

Earth's 23.5-degree tilt causes seasons because it changes the angle and duration of sunlight reaching each hemisphere.

Moon phases in order: new, waxing crescent, first quarter, waxing gibbous, full, waning gibbous, third quarter, waning crescent.

Solar eclipse: Moon between Earth and Sun at new moon; lunar eclipse: Earth between Sun and Moon at full moon.

Cell theory: all living things are made of cells, cells are the basic unit of life, and new cells arise from preexisting cells.

Key organelles: nucleus stores DNA; mitochondria carry out aerobic respiration; chloroplasts carry out photosynthesis; ribosomes build proteins.

Photosynthesis: 6CO2 + 6H2O + light energy -> C6H12O6 + 6O2; it occurs in chloroplasts and stores energy in glucose.

Cellular respiration: C6H12O6 + 6O2 -> 6CO2 + 6H2O + ATP; it releases energy from glucose in mitochondria.

Protein synthesis follows DNA -> RNA -> protein; DNA bases A-T and C-G pair, while RNA uses U instead of T.

Mitosis produces two genetically identical diploid cells for growth and repair; meiosis produces four haploid gametes with genetic variation.

Genetics: a dominant allele is expressed when one copy is present; a recessive allele is expressed only when two copies are present.

Natural selection requires heritable variation and differential survival or reproduction, which changes allele frequencies over generations.

Energy flows from producers to consumers to decomposers; about 10 percent of energy transfers to the next trophic level, and the rest is lost as heat.

Newton's first law: an object maintains constant velocity unless a net external force acts on it (inertia).

Newton's second law: F = ma; acceleration is proportional to net force and inversely proportional to mass.

Newton's third law: for every action force, there is an equal and opposite reaction force on a different object.

Motion formulas: speed = distance/time; acceleration = change in velocity/time; momentum = mass x velocity.

Energy conservation: energy changes form but total energy in a closed system remains constant; KE = 1/2 mv^2 and gravitational PE = mgh.

Work = force x distance (when force and motion are parallel); power = work/time; both are measured in joules and watts.

Wave equation: v = f lambda; wave speed equals frequency times wavelength.

Transverse waves oscillate perpendicular to travel; longitudinal waves oscillate parallel; sound is longitudinal and needs a medium.

Matter: atoms are elements; compounds are chemically bonded elements; mixtures are physically combined and can be separated without chemical change.

Scientific investigation: pose a question, form a testable hypothesis, design a controlled experiment, collect data, analyze, and conclude.

Variables: independent variable is changed, dependent variable is measured, and controlled variables are kept constant.

A control group does not receive the treatment and serves as a baseline for comparison.

Engineering design cycle: define the problem and constraints, brainstorm, build a prototype, test, evaluate, and iterate.

Trade-offs: every design choice has costs and benefits; optimize by comparing criteria and constraints.

SI units: length in meters, mass in kilograms, time in seconds, temperature in kelvin; metric prefixes scale by powers of ten.

Accuracy is closeness to the true value; precision is repeatability; random errors reduce precision, systematic errors reduce accuracy.

Data summary: mean = sum/number; median = middle value; mode = most frequent; range = maximum minus minimum.

Models and simulations simplify real systems, so they can explain and predict but must be revised when evidence contradicts them.