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119 terms

science vocab

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absolute zero
the lowest possible temperature, about -273 degrees Celsius
acid
a substance that forms hydronium ions in water; having a pH less than 7
acid rain
rain made acid by absorbing sulfur and nitrogen oxides from polluted air
adrenalin
a hormone of the adrenal gland, secreted in times of emergency
air mass
a large body of air characterized by certain values of temperature and humidity
algae
simple, green organisms with cell walls, but without the complex structure of plants
alkali
a strongly basic hydroxide
alloy
a substance composed of two or more metals
alternating current
an electric current that reverses direction periodically
amino acid
organic chemicals with an acid group (-COOH) at one end and an amino group (-NH2) at the other; the constituent molecules of proteins
anemia
substandard concentration of red blood cells
antibody
a blood protein that protects the body from foreign chemicals or microorganisms
aorta
the largest artery, carrying blood out of the left ventricle
artery
a muscular-walled blood vessel that distributes blood to the body tissues
atmosphere
the layer of air surrounding the earth
atom
the smallest part of an element
bacteria
the smallest and simplest one-celled organisms, having neither nucleus nor other organelles
barometer
an instrument for measuring atmospheric pressure
bedrock
the solid rock underlying the loose material at the earth's surface
boiling point
the temperature at which, at any given pressure, the liquid and gas phases of a substance are in equilibrium
calorie
a quantity of heat energy, equal to 4.185 joules; the Large Calorie of the nutritionist is a kilocalorie, equal to 1000 calories
capillary
1) a thin tube into which water can rise by adhesion to the surface 2) a tiny blood vessel connecting an artery to a vein and providing interchange of materials between blood and tissue
catalyst
a substance that increases the rate of a chemical reaction without being used up in the reaction
chemical formula
conventional representation of the atomic composition of a compound
chemical reaction
a process in which the molecules or ionic composition of one or more substances is altered
colon
the large intestine
concentration
the amount of a substance contained in a given volume of a solution or other mixture
conductor
a material through which heat or electrical current may pass
digestion
the process of enzymatic breakdown of large organic molecules into smaller, soluble ones
dilute solution
a solution in which the solute has a low concentration
DNA
deoxyribose nucleic acid, the substance of the genes
ductless gland
an endocrine organ
ecology
the study of the relationships between organisms and with their inorganic environment
electric charge
the property of particles (such as electrons and protons) by which they exert forces on each other without respect to their mass
electric current
a flow of electric charge, typically carried by electrons through a metal or by ions through a solution or a plasma
electromagnetic waves
disturbances in electric and magnetic fields propagating through space
electron
a particle found in all atoms, having a small mass and a single unit of negative electric charge
electrostatic force
the force particles exert on each other because of their electric charge
element
a substance consisting of only one species of atom, so that it cannot be decomposed by chemical means
embryo
an organism in the earliest stages of its development
endocrine organ
a gland that secretes hormones into the blood
energy
a physical quantity having the dimension of work and measured in joules, whose total quantity remains constant through all interactions and transformations
enzyme
a substance, usually a protein, produced by living cells and acting as a catalyst
epicenter
the point on the earth's surface directly above the geological shift that causes an earthquake
erosion
the movement of rock, sand, etc., due to natural forces
esophagus
the tube that carries food from the mouth to the stomach; gullet
evaporation
conversion of a liquid into the gaseous phase by escape of molecules from the surface
evolution
the process by which species undergo drastic changes over long periods of time
excretion
the disposal of metabolic wastes from the body, as by urination
fault
a crack in the earth's crust, along which crustal movement takes place
fermentation
an enzyme-controlled reaction that takes place in the absence of oxygen, such as the conversion of sugar to alcohol by the action of yeast
fertilization
1) the process of applying nutrients to the soil to stimulate plant growth 2) the union of a sperm and an egg cell to form a zygote
fission
1) reproduction of a one-celled organism by splitting into two equal parts 2) the splitting of an atomic nucleus into approximately equal parts, with the release of energy
flood plain
the flat region around an old river, which becomes covered with water at times of high runoff
food chain
an array of organisms in which each serves as food for the one above
fossil
the preserved remains or casts of a long-extinct organism
frequency
the number of cycles completed in a unit time in any cyclic phenomenon, such as a vibration
front
the boundary between two air masses
fusion
1) the melting of a solid 2) a nuclear reaction in which two small nuclei combine to form a larger one, accompanied by the release of energy 3) the union of isogametes of one-celled organisms
galaxy
an agglomeration of many millions of stars
gamete
a sex cell, such as egg or sperm
gas
a substance, usually of very low density, that has no surfaces of its own but will spread to fill its container
gene
the particle that carries hereditary info from one generation to another and controls the production of proteins in a living cell
genetics
the study of biological inheritance
glacier
a large mass of ice moving down a valley or across a continent
glucose
the simple sugar that forms the fundamental energy supply of all nucleated organisms
gravity
the mass-dependent force by which any two objects in the universe attract each other
greenhouse effect
the warming of the earth resulting from atmospheric gases trapping heat that reradiates from the earth's surface
habitat
the part of an ecosystem that is occupied by a given organism
heat
energy that passes from one system to another because of a difference in temperature
helix
a spiral shaped like a spring, characteristics of the DNA molecule
herbivore
an animal that eats plants only (what Hibari hates the most)
hormone
a substance, secreted into the blood by an endocrine gland, that controls chemical processes in other parts of the body
humidity
the amount of water vapor in the air
igneous rock
rock formed by the hardening of liquid rock emerging from deep within the earth, either to the surface or within the crust
inertia
the property of objects to remain in a state of rest or uniform motion in a straight line unless acted on by an outside force
infrared rays
electromagnetic waves of wavelength longer than those of visible light, but shorter than microwaves
insulator
a substance that blocks the passage of heat or electric current
insulin
a hormone, produced in the pancreas, that controls the metabolism of glucose
ion
an atom or group of atoms that has acquired either a positive charge or a negative charge by gaining/losing electrons
isobar
a line on a weather map connecting points of equal barometric pressure
isotope
a variety of an element distinguished by its atomic mass number, but having the same atomic number as all other isotopes of the element
jet stream
a rapidly flowing mass of air high in the atmosphere
Kelvin scale
the SI temperature scale, which has its zero at the absolute zero of temperature
kinetic energy
the energy of an object as measured by its mass and velocity
latent heat
the heat added or removed from a substance that produces a change of phase with no change in temperature
latitude
the distance north or south of the equator measured in degrees
light year
the distance light travels in a year
liquid
a substance that takes the shape of its container, up to a definite upper surface
liter
a unit of volume equal to 1000 cubic cm
longitude
the distance east or west of the prime meridian, measured in degrees
lunar eclipse
condition in which the earth comes between the sun and the moon so that the moon is in the earth's shadow
magnet
a device made of a ferromagnetic material, such as steel, which can exert forces on other such materials
magnetism
the excess force exerted on each other by charges in motion
mass
the quantity of substance in an object measured either by its acceleration when a force is applied or by its gravitational attraction to other objects
melting
the change of matter from solid to liquid
melting point
the temperature at which the solid and liquid phases of a substance can exist in equilibrium
mineral
an earth substance with specified chemical constitution
molecule
a particle consisting of one or more atoms bound together, and comprising the smallest quantity of a non-ionic substance
muscle
an organ that controls body functions by carrying electrochemical impulses
natural selection
the tendency of individuals or species best adapted to a particular environment to leave larger numbers of offspring
nerve
an organ that controls body functions by carrying electrochemical impulses
neuron
a nerve cell
neutron
a neutral particle that is part of the nuclei of atoms, with mass slightly larger than that of a proton
nitrogen
a gaseous element that makes up 79 percent of the atmosphere
nucleus
1) the massive, charged center of an atom, composed of protons and neutrons 2) a structure in a cell, surrounded by a membrane and containing the chromosomes 3) a particle of dust in the atmosphere around which water condenses, forming a raindrop
organic compound
a molecular chemical compound based on carbon
osmosis
the diffusion of water through a membrane
outcrop
the part of the bedrock protruding through overlying sediments
ovary
in animals, an organ that produces egg cells; part of the stigma of a flower that contains the ovules
thermometer
a device for measuring temperature
toxin
a poisonous substance produced by bacteria
vaccine
a material used to induce immunity to a specific disease
vertebrae
the bones that are arrayed linearly to form the back-bone of vertebrates
virus
a submicroscopic particle that can become self-reproducing inside a living cell
volt
the unit of measure of electric potential difference, which provides the condition for the flow of an electric current
weight
the gravitational force that the earth or other astronomical object exerts on an object near its surface
X-ray
electromagnetic radiation of wavelength shorter than ultraviolet
zygote
a cell formed by the fusion of two gametes