Science, Grades 9-12 – 141 Words


a pedal that controls the throttle valve


(meteorology) the horizontal transfer of heat or other atmospheric properties

Albert Einstein

physicist born in Germany who formulated the special theory of relativity and the general theory of relativity; Einstein also proposed that light consists of discrete quantized bundles of energy (later called photons) (1879-1955)

Antoine Lavoisier

French chemist known as the father of modern chemistry


a man-made object

atomic bomb

a nuclear weapon in which enormous energy is released by nuclear fission (splitting the nuclei of a heavy element like uranium 235 or plutonium 239)

atomic energy

the energy released by a nuclear reaction

atomic mass

the property of an atom that causes it to have weight

atomic number

quantity of protons in the nucleus of an atom of an element

atomic theory

a theory of the structure of the atom

atomic weight

(chemistry) the mass of an atom of a chemical element expressed in atomic mass units

big bang theory

(cosmology) the theory that the universe originated sometime between 10 billion and 20 billion years ago from the cataclysmic explosion of a small volume of matter at extremely high density and temperature


of or pertaining to a number system having 2 as its base


the branch of molecular biology that studies the use of microorganisms to perform specific industrial processes


a small piece or quantity of something


the tendency to float in water or other liquid


a sequence of data processed as a single unit of information


an abundant nonmetallic element in all organic compounds

carbon atom

an atom of carbon

carbon cycle

the organic circulation of carbon from the atmosphere into organisms and back again

carbon dioxide

a heavy odorless colorless gas formed during respiration and by the decomposition of organic substances; absorbed from the air by plants in photosynthesis


substance that initiates or accelerates a chemical reaction

cell membrane

a thin membrane enclosing the cytoplasm of a cell

cell nucleus

a part of the cell containing DNA and RNA and responsible for growth and reproduction

cell organelle

a specialized part of a cell; analogous to an organ

cell wall

a rigid layer of polysaccharides enclosing a plant membrane

Charles Darwin

English natural scientist who formulated a theory of evolution by natural selection (1809-1882)

chat room

a site on the internet where a number of users can communicate in real time (typically one dedicated to a particular topic)

chemical bond

an electrical force linking atoms


a small fragment of something broken off from the whole


plastid containing chlorophyll and other pigments


a process used for separating mixtures by virtue of differences in absorbency


a threadlike strand of DNA that carries genes

closed-loop system

a control system with a feedback loop that is active


transfer of heat caused by molecular motion in liquid or gas


Polish astronomer who produced a workable model of the solar system with the sun in the center (1473-1543)


the part of a computer that does most of the data processing


the substance inside a cell, not including the nucleus


locate and correct errors in a computer program code


a long linear polymer found in the nucleus of a cell

Doppler effect

change in the apparent frequency of a wave as observer and source move toward or away from each other


pull, as against a resistance


the tendency of a body to return to its original shape

electric motor

a motor that converts electricity to mechanical work

electric potential

the difference in electrical charge between two points in a circuit expressed in volts

electromagnetic radiation

radiation consisting of waves of energy associated with electric and magnetic fields resulting from the acceleration of an electric charge

electromagnetic spectrum

the entire frequency range of electromagnetic waves

electromagnetic wave

radiation consisting of waves of energy associated with electric and magnetic fields resulting from the acceleration of an electric charge


an elementary particle with negative charge

elementary particle

a particle that is less complex than an atom

endothermic reaction

a chemical reaction accompanied by the absorption of heat

Enrico Fermi

Italian nuclear physicist (in the United States after 1939) who worked on artificial radioactivity caused by neutron bombardment and who headed the group that in 1942 produced the first controlled nuclear reaction (1901-1954)


a numerical measure of the uncertainty of an outcome


a complex protein produced by cells that acts as a catalyst

Ernest Rutherford

British physicist (born in New Zealand) who discovered the atomic nucleus and proposed a nuclear model of the atom (1871-1937)

exothermic reaction

a chemical reaction accompanied by the evolution of heat

experimental method

the use of controlled observations and measurements to test hypotheses

external storage

a data storage device that is not the main memory of a computer


of or relating to a temperature scale proposed by the inventor of the mercury thermometer


extensive tract of level open land


the internal structure that gives an artifact its shape

gamma ray

electromagnetic radiation emitted during radioactive decay and having an extremely short wavelength

gene expression

conversion of the information encoded in a gene first into messenger RNA and then to a protein

general theory of relativity

a generalization of special relativity to include gravity

genetic mutation

any event that changes genetic structure

geologic time

the time of the physical formation and development of the earth (especially prior to human history)

geological dating

use of chemical analysis to estimate the age of geological specimens

germ theory

(medicine) the theory that all contagious diseases are caused by microorganisms


a unit of information equal to 1000 megabytes or 10^9 bytes

Golgi apparatus

a netlike structure in the cytoplasm of animal cells

greenhouse gas

a gas that contributes to the greenhouse effect by absorbing infrared radiation

Gregor Mendel

Augustinian monk and botanist whose experiments in breeding garden peas led to his eventual recognition as founder of the science of genetics (1822-1884)


a set of tags and rules (conforming to SGML) for using them in developing hypertext documents

hydrogen bomb

a nuclear weapon that releases atomic energy by union of light (hydrogen) nuclei at high temperatures to form helium

hydrogen ion

a positively charged atom of hydrogen


assign an initial value to a computer program


a particle that is electrically charged positive or negative


atom with same atomic number, different number of neutrons

Johannes Kepler

German astronomer who first stated laws of planetary motion

John Dalton

English chemist and physicist who formulated atomic theory and the law of partial pressures; gave the first description of red-green color blindness (1766-1844)


British physicist who invented the Kelvin scale of temperature and pioneered undersea telegraphy (1824-1907)


a unit of information equal to 1000 bytes

Lise Meitner

Swedish physicist (born in Austria) who worked in the field of radiochemistry with Otto Hahn and formulated the concept of nuclear fission with Otto Frisch (1878-1968)


very large in scale or scope or capability

magnetic field

the lines of force surrounding a permanent magnet or a moving charged particle


a unit of information equal to 1000 kilobytes or 10^6 bytes


cell division in sexually reproducing organisms


integrated circuit semiconductor chip that performs the bulk of the processing and controls the parts of a system


kitchen appliance that cooks food by passing an electromagnetic wave through it; heat results from the absorption of energy by the water molecules in the food


an organelle containing enzymes responsible for producing energy


the process by which a cell divides into two smaller cells


a small congenital pigmented spot on the skin

natural object

an object occurring naturally; not made by man

natural selection

a process in which organisms evolve to adapt to environment


a cell that is specialized to conduct nerve impulses


a neurochemical that transmits nerve impulses across a synapse


an elementary particle with zero charge

Newtonian mechanics

the branch of mechanics based on Newton’s laws of motion


a common nonmetallic element that is normally a colorless odorless tasteless inert diatomic gas; constitutes 78 percent of the atmosphere by volume; a constituent of all living tissues

nitrogen cycle

the circulation of nitrogen

nuclear fission

a nuclear reaction in which a massive nucleus splits into smaller nuclei with the simultaneous release of energy

nuclear fusion

a nuclear reaction in which nuclei combine to form more massive nuclei with the simultaneous release of energy


a unit of electrical resistance equal to the resistance between two points on a conductor when a potential difference of one volt between them produces a current of one ampere

operating system

(computer science) software that controls the execution of computer programs and may provide various services


a colorless gas that is a screen for ultraviolet radiation


a document granting an inventor sole rights to an invention

peripheral device

(computer science) electronic equipment connected by cable to the CPU of a computer


involving direct communication or contact between persons or parties


the smallest discrete component of an image on a screen

plate tectonics

the movement or study of the movement of Earth’s crust

potential energy

mechanical energy that a body has by virtue of its position


the exertion of force to a surface


an organic compound essential to living cells


a stable particle with positive charge


Alexandrian astronomer (of the 2nd century) who proposed a geocentric system of astronomy that was undisputed until the late Renaissance

radio wave

an electromagnetic wave with a wavelength between 0.5 cm to 30,000 m

radioactive dating

measurement of the amount of radioactive material (usually carbon 14) that an object contains; can be used to estimate the age of the object

radioactive decay

the spontaneous disintegration of a radioactive substance along with the emission of ionizing radiation


the most common computer memory which can be used by programs to perform necessary tasks while the computer is on; an integrated circuit memory chip allows information to be stored or accessed in any order and all storage locations are equally accessible


the attribute of being superfluous and unneeded


someone who scans verse to determine the number and prosodic value of the syllables


the act of keeping apart


a substance as germanium or silicon whose electrical conductivity is intermediate between that of a metal and an insulator; its conductivity increases with temperature and in the presence of impurities

sex cell

a spermatozoon or an ovum


the act of imitating the behavior of some situation

sound wave

(acoustics) a wave that transmits sound

space probe

a rocket-propelled guided missile that can escape the earth’s atmosphere; makes observations of the solar system that cannot be made by terrestrial observation


unwanted e-mail

special theory of relativity

a physical theory of relativity based on the assumption that the speed of light in a vacuum is a constant and the assumption that the laws of physics are invariant in all inertial systems


the evolution of a biological species

speed of light

the speed at which light travels in a vacuum


the circulation of cytoplasm within a cell


a system that is part of some larger system


a model or standard for making comparisons

thermal equilibrium

a state in which all parts of a system are at the same temperature


a twisting force


any agent that carries and transmits a disease

ultraviolet radiation

radiation lying in the ultraviolet range


a tiny cavity filled with fluid in the cytoplasm of a cell


resistance of a liquid to flowing


take a photograph with a stream of high-energy photons
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