6th grade science vocabulary words
abiotic factor - nonliving physical or chemical part of an ecosystem; describes the nonliving part of the
environment, including water, rocks, light, and temperature.
abrasion - grinding and wearing away of rock surfaces through the mechanical action of other rock or sand
particles driven by water, wind, or gravity.
absolute dating - any method of measuring the age of an event or object in years.
absolute magnitude - amount of light a star actually gives off; a measure of how bright a star would be if it
were seen from a standard distance.
absolute zero - temperature at which molecular energy is at a minimum (0 K on the Kelvin scale or -
273.16oC on the Celsius scale)
absorption (absorb) - process of taking in; soaking up; or making a part of something.
abyssal plain - large, flat, almost level area of the deep-ocean basin.
abyssal zone - open-ocean zone that extends from about 2 000 meters down to about 6 000 meters down.
acceleration - rate at which speed or direction changes; can be found by dividing the change in speed by the
given time, usually expressed in meters per second.
accuracy - extent to which a measurement is in proximity to the standard or expected value.
acid - substance that increases the H+ concentration when added to a water solution.
acid precipitation - rain, sleet, or snow that contains a high concentration of acids.
acid rain - rain that has become more acidic than normal due to pollution.
activation energy - least amount of energy required to start a particular chemical reaction.
active transport - movement of molecules from where they are less crowded to where they are more
crowded; the process of using energy to move materials through a membrane.
adaptation - any structure or behavior that helps an organism survive in its environment; a characteristic of
an organism that
increases its chance of survival in its environment; a particular development, behavior, or physiological
change in a population of organisms, in response to changes in the populations.
adenosine triphosphate (ATP) - molecule that acts as the main energy source for cell processes.
adoptive family - legal addition of children to the family of non-biological parents.
air mass - large body of air that has nearly the same temperature and humidity as the Earth’s surface over
which it formed.
air pollution - contamination of the atmosphere by the introduction of pollutants from human and natural
sources.
air pressure - measure of the force of air molecules pushing on a surface.
air quality - measure of the pollutants in the air that is used to express how clean or polluted the air is.
air resistance - force of air on moving objects.
alga (plural-algae) - protists that live mostly in water and use sunlight as a source of energy.
allele - any of two or more alternate forms of a gene that an organism may have for a particular trait.
alloy - solid metal dissolved in another solid metal.
alluvial fan - fan-shaped deposit of sediment at the base of a slope, formed as water flows down the slope
and spreads at the bottom.
altitude - distance above sea level.
alveolus (plural-alveoli) - grape-like cluster of tiny “balloons” in the lungs.
ameba (amoeba) - microscopic, unicellular Protist that moves using pseudopod.
amino acid - building block of protein; an organic molecule containing an amino (-NH2) and a carboxyl(-
COOH) group from which proteins are synthesized.
ammonia - poisonous gas made of nitrogen and hydrogen.
amorphous solid - solid that does not keep a definite shape.
amphibian - cold-blooded vertebrate animal that lives in water when it is young and as an adult, it moves
onto land.
amplitude - measure of the energy a wave carries; the maximum distance that the particles of a wave’s
medium vibrate from their rest position; in any periodic function, the maximum absolute variation of the
function.
anabolic (anabolism) - building up process.
anal pore - tiny opening through which a paramecium and other unicellular organisms eliminates waste.
analyze (analysis/plural-analyses) - to separate into parts in order to determine what something is or how it
works; to examine in detail.
anatomy - study of the structure of the body.
anemometer - instrument used to measure wind speed.
angiosperm - plant that has flowers and produces seeds enclosed in
fruit.
Animalia (Animal) - kingdom made up of complex, multicellular organisms that lack cell walls, can usually
move around, and
anion - atom that has gained electrons; a negative ion.
anther - part of the stamen that produces
pollen. 1
antibiotic - substance produced by helpful bacteria that destroys or weakens disease-causing bacteria.
antibody - substance produced in and by the body that protects against specific disease
infections.
anticline - upward fold in a rock layer.
anticyclone - rotation of air around a high-pressure center in the direction opposite to Earth’s rotation.
antigen - any foreign substance that causes an immune response.
aorta - largest artery in the body.
aphelion - in the orbit of a planet or other body in the solar system, the point that is farthest from the sun.
apogee - point of the moon’s orbit farthest from the Earth.
apparent magnitude - brightness of a star as it appears from Earth.
aqueous - solution containing water.
aquifer - body of rock or sediment that stores groundwater and allows the flow of groundwater.
Archaean (plural-Archaea) - kingdom made up of unicellular prokaryotic cells that can survive in extreme
environments.
archeology (archaeology) - study of the cultural remains of ancient people.
archipelago - group or chain of islands clustered together in a sea or ocean.
area - a measure of the size of a surface or a region.
artery - blood vessel that carries blood away from the heart.
artesian spring - spring whose water flows from a crack in the cap rock over the aquifer.
artificial satellite - any human-made object placed in orbit around a body in space.
arthropod - invertebrate animal with an exoskeleton, a segmented body, and jointed legs.
asexual reproduction - formation of an organism from a single cell; form of reproduction in which new
individuals are formed
without the involvement of gametes.
assumption (assume) - is something taken for granted or accepted as true without proof.
asteroid - tiny chunks of rock of varying sizes that orbit the sun.
asteroid belt - area in space where hundreds of thousands of asteroids orbit the sun between Mars and
Jupiter.
asthenosphere - solid, plastic layer of the mantle beneath the lithosphere; layer made of rock that flows very
slowly,
which allows tectonic plates to move on top of it.
astronomical unit (AU) - average distance from Earth to the sun, which is used to measure vast distances in
space. (approximately 150 million kilometers)
astronomy - study of planets, stars and other objects beyond the Earth.
atmosphere - mixture of gases that surround Earth, other planets, moons or stars.
atoll - ring of coral reefs that surrounds an island that has sunk beneath the waves.
atom - tiny particle of matter consisting of a nucleus that contains protons and neutrons and an electron
cloud that contains
electrons; the smallest unit of a chemical element that can still retain the properties of that element; building
block of
matter.
atomic mass - average of the masses of all the existing isotopes of an element.
atomic mass unit (amu) - unit used to measure the masses of subatomic particles; a proton has a mass of
one amu.
atomic number - number of protons in the nucleus of an atom; number that identifies the kind of atom; the
number determines an
ATP - see adenosine triphosphate.
atrium (plural-atria) - upper heart chamber.
aurora - bands of light given off by collisions of particles in the Earth’s upper atmosphere.
autotroph - organism that makes its own food from simple substances; producer; an organism that captures
energy from sunlight
and uses it to produce energy-rich carbon compounds, usually through the process of photosynthesis.
autumnal equinox - first day of autumn. (September 20 or 21)
average speed - distance traveled divided by the time it takes to travel this distance.
axis (plural-axes) - imaginary line drawn through the center of a body around which the body rotates or
spins; a reference to the
line in a coordinate system or graph.
bacillus (plural-bacilli) - rod-shaped bacterium.
background radiation - energy left from the big bang that is spread evenly throughout the universe.
Bacteria - kingdom made up of unicellular prokaryotic cells that usually have a cell wall and reproduce by
binary fission.
bacteriophage - virus that infects bacterial cells.
bacterium (plural-bacteria) - unicellular, heterotrophic microorganism containing no nuclear membrane.
balanced forces - describes forces acting on an object that cancel each other.
bar graph - tool that uses bars to show the relationships between variables; can be horizontal or vertical and
can display any
barometer - instrument that measures air pressure in the atmosphere.
barrier island - long ridge of sand or narrow island that develops parallel to a coast as a sandbar builds up
above the water’s
surface.
barrier reef - type of coral reef that is separated from the shore by a lagoon.
base - substance that increases the OH- concentration of a solution; a proton acceptor.
batholith - huge, irregularly shaped intrusion that extends deep in the Earth’s
crust. 2
bathyal zone - open-ocean zone that extends from a continental slope down about 2 000 meters.
bay - body of water that is partly enclosed by land.
beach - area of the shoreline that is made up of deposited sediment.
bedrock - layer of rock beneath soil.
behavior - organism’s action in response to a stimulus.
benthic - region near the bottom of a pond, lake, or ocean.
benthos - organisms that live at the bottom of oceans or bodies of fresh water.
bias - preference for a person or thing that interferes with impartial judgment; a prejudice.
big bang theory - states the universe was formed by the explosion of a small amount of very dense and hot
matter.
bile - substance produced by the liver that aids in digestion.
binary fission - form of asexual reproduction for prokaryotic cells such as bacteria.
binary star - double star system in which two stars revolve around each
other.
binomial nomenclature - naming system in which organisms are given two names: a genus and species.
biodiversity - existence of a wide range of different species in a given area or specific period of time.
biology - study of life and all living things; ecology, zoology, and botany are examples of biological
sciences.
biomass - plant material, manure, or any other organic matter that is used as an energy source.
biomes - large geographic areas with similar climates and ecosystems; the six most common are tundra,
taiga, temperate forest,
tropical rain forest, grassland, and desert; a complex biotic community characterized by the interaction of
living
organisms and climatic factors.
biosphere - all living organisms on Earth in the air, on the land, and in the waters; the part of Earth where
life exists.
biotic factor - living thing in an ecosystem; describes the living part of the environment relating to, caused
by, or
produced by living organisms.
bituminous - dark brown or black coal found deep within the Earth and called soft coal.
black hole - core of a very massive star that remains after a supernova explosion.
blizzard - blinding snow storm with winds of at least 56 km/hr, usually with temperatures below -7 oC.
blue shift - shift toward the blue end of the spectrum of a star moving toward the Earth.
boiling - process in which particles of a liquid change to gas, travel to the surface of the liquid and then into
the air.
bone - hard stiff material containing the minerals calcium and phosphorus.
botany - study of plants.
Boyle’s Law - law stating that the volume of a fixed amount of gas varies indirectly with the pressure of the
gas.
bronchus (plural-bronchi) - tube that branches off from the trachea.
budding - reproductive process in yeast, in which a new yeast cell is formed from a tiny bud.
butte - flat-topped rock or hill formation with steep sides.
caldera - large, circular depression that forms when the magma chamber below a volcano partially empties
and causes the ground
above to sink.
calorie - unit of energy; the amount of heat needed to raise one gram of water one degree Celsius at standard
atmospheric pressure.
canyon - deep valley with very steep sides—often carved from the Earth by a river.
cape - pointed piece of land that sticks out into a sea, ocean, lake or river.
capillary - tiny thin-walled blood vessel.
carbohydrate - organic compound made up of the elements carbon, hydrogen and oxygen, and a main
source of energy for living
things; include sugars and starches used for energy or as structural materials.
carbonation - process in which carbonic acid reacts chemically with another substance.
carbon cycle - continuous movement of carbon through Earth, its atmosphere, and the living things on Earth.
cardiac muscle - muscle found only in the heart.
carnivore - animal or plant that consumes or obtains nutrients from animals.
carrying capacity - maximum size that a population can reach in an ecosystem.
cartilage - strong, flexible connective tissue that supports such structures as the nose and ears.
catabolic (catabolism) - breaking down process.
cast - type of fossil that forms when sediments fill in the cavity left by a decomposed organism.
catalyst - substance that speeds up or slows down chemical reactions, but is not itself changed by the
reaction; a substance that
speeds up or slows down the rate of a reaction without being consumed or altered.
cation - atom that has lost electrons; a positive ion.
cause - reason for an action or a condition.
cavern -
cave.
cell - smallest, basic unit of structure and function in a living thing; building block of life.
cell membrane - thin, flexible envelope of protoplasm that forms the outer covering of an animal cell and
that is inside the cell
wall of a plant cell; controls movement of materials into and out of the cell.
cell theory - major theory based on observations and conclusions by many scientists that states that the cell
is the basic unit of life,
organisms are composed of one or more cells, and all cells come from other cells.
cellular respiration (respiration) - process in which cells use oxygen to release energy stored in sugars.
cellulose - forms the rigid cells walls of plants; organic compound made of long chains of glucose
molecules. 3
cell wall - outermost boundary of plant and bacterial cells.
Celsius (oC) - temperature scale used in the metric system at which water freezes at 0o and boils at 100o.
cementation - process by which sediments are cemented together by minerals dissolved in water to form
sedimentary rock.
centrifugal - motion away from the center of axis.
centrioles - one of the two tiny parts found in the centrosome composed of microtubules.
centripetal force - inward force on a particle or object moving in a circular path.
centrosome - small organelle just outside the nucleus that contains the centrioles and is involved with
mitosis.
cepheid variable - pulsating variable star; star that varies in brightness and size.
chain of infection - series of infections that is directly or immediately connected to a particular source.
change of state - physical change that occurs when matter changes to another state.
channel - path that a stream follows.
characteristic - property, feature, quality or trait that describes an object.
Charles’s Law (Charles’) - law stating that the volume of a fixed amount of gas varies directly with the
temperature of the gas.
chemical change - change a substance undergoes when it turns into another
substance.
chemical digestion - breaking down of food by enzymes.
chemical energy - energy that is stored in the chemical composition of matter; the energy released when a
chemical compound
reacts to produce new compounds.
chemical equation - description of a chemical reaction using symbols and formulas.
chemical formula - combination of chemical symbols used as a shorthand for the names of chemical
substances.
chemical property - property that describes a substances ability to change into another substance.
chemical reaction - process by which a substance is changed into another substance through a
rearrangement or new combination
of its atoms.
chemical rock - sedimentary rock formed from large amounts of minerals when a body of water dries up.
chemical symbol - shorthand way of representing the elements; usually consists of one or two letters, the
first of which is always
capitalized, but the second is never capitalized.
chemical weathering - breakdown and alteration of rocks at or near Earth’s surface as a result of
chemical processes.
chemistry - study of what substances are made of and how they change and combine.
chlorofluorocarbons (CFCs) - group of chemical compounds used in refrigerators, aerosol sprays, and foam
packaging that
chloroplast - large, irregularly shaped organelle that contains the green pigment needed for photosynthesis.
chordate - animal with a notochord, a dorsal hollow nerve cord, and gill slits.
chromatin - material that makes up the chromosomes found in the nucleus.
chromosome - thick, rod-like object found in the nucleus that directs the activities of the cell and passes on
the traits of the cell to
new cells.
chromosphere - middle layer of the sun’s atmosphere.
cilium (plural-cilia) - small, hair-like projection on the outside of a cell used for movement.
cinder - small volcanic bomb about the size of a golf ball.
cinder cone - volcano made mostly of cinders and other rock particles that have been blown into the air.
circle graph - tool used to show the parts of a whole.
circuit - interconnection of electrical elements forming a complete path for the flow of current.
circulatory system - body system that transports materials.
cirrus cloud - feathery, fibrous cloud that forms at a very high altitude.
class - classification group between phylum and order.
classification - is the grouping of living things according to similar characteristics.
classification key - system for identifying organisms by using pairs of descriptions.
classify - to group information, objects, or ideas based on their similarities.
clastic rock - sedimentary rocks made up of rock fragments mixed with sand, clay and mud.
cleavage - breakage of a mineral along definite lines or smooth, flat surfaces.
cliff - steep face of rock and soil.
climate - pattern of weather that occurs in a particular area over a long period of time.
climate zone - one of the major divisions in a system for classifying the climates of different regions based
on characteristics they
have in common.
climax community - community that has reached the final stage of ecological succession.
cloud - collection of small water droplets or ice crystals suspended in the air, which forms when the air is
cooled and condensation
occurs.
cnidarian - invertebrate animal that has a body with radial symmetry, tentacles with stinging cells, and a
central internal cavity.
coal - fossil fuel that forms underground from partially decomposed plant material.
coastal plain - low, flat area along the coast.
coastline - location where land and ocean surface meet.
coccus (plural-cocci) - sphere-shaped bacterium.
coefficient - number placed in front of a chemical formula in a chemical equation so that the equation is
balanced. 4
cold - is the absence of heat.
cold-blooded - having a body temperature that can change somewhat with changes in the temperature of the
environment.
cold front - type of front that forms when a mass of cold air meets and replaces a mass of warm air.
colonial - unicellular organisms that live independently but clustered side by side.
coma - cloud of gas and dust surrounding the nucleus of a comet.
comet - object made of ice, gas and dust that orbits the sun.
commensalism - interaction between two species in which one species benefits without harming the other.
communicable - capable of spreading from one diseased person or animal to another person or animal,
either directly or indirectly.
communications satellite - artificial satellite that beams television programs, radio messages, telephone
conversations, and other information all over the world.
community - all the populations of organisms belonging to different species and sharing the same
geographical area.
compaction - process by which layers of sediments are pressed together to form sedimentary rock.
competition - struggle among living things to get the proper amount of food, water and energy from the
environment.
composite volcano - volcano built up of alternating layers of rock particles and lava
composition - chemical makeup of a rock; describes either the minerals or other materials in the rock.
compound - substance made up of molecules that contain more than one kind of atom; two or more elements
chemically
combined; a substance made up of at least two different elements held together by chemical bonds that
can only be
broken down into elements by chemical processes.
compound light microscope - microscope containing more than one lens that uses light to make an object
look larger.
compound machine - combination of two or more simple machines.
compression - stress that occurs when forces act to squeeze an object.
compressional wave - wave in which matter in the medium moves forward and backward in the same
direction the wave travels.
concentration - relative amount of a particular substance, a solute, or mixture.
conclusion - summary of the results of the experiment where data is analyzed to determine the meaning of
what
happened in the experiment.
condensation - process in which a gas loses heat energy and changes into a liquid; the act of making more
dense or compact.
conditioning - process in which behavior is modified so that a response associated with one stimulus
becomes associated with
another stimulus.
conduction - transfer of energy that occurs when molecules bump into each other; the transmission of heat
through a medium and
without the motion of the medium; the process by which energy is transferred from a warmer object to a
cooler object by
means of physical contact.
conifer - cone-bearing trees and shrubs that usually keep their leaves or needles during all the seasons of the
year.
conjugation - type of sexual reproduction in unicellular organisms in which hereditary material is
exchanged.
conservation - controlled use and/or maintenance of natural resources; the wise use of and preservation of
natural resources.
conservation of energy - states that energy cannot be created nor destroyed but only changed from one form
to another.
conservation of mass (conservation of matter) - states that mass cannot be created or destroyed.
constant - factor in an experiment that does not change.
constellation - group of stars in which people thought they saw imaginary figures of animals or people; a
star pattern identified
and named as a definite group.
constructive boundary - type of plate boundary where new material is added to the plates.
consumer - organism that feeds on other organisms for food. (heterotroph)
contact metamorphism - type of metamorphism that occurs when rocks are heated by contact with magma
or lava.
continental climate - climate that occurs in the interior of a continent, with large temperature differences
between seasons.
continental crust - section of the Earth’s crust that makes up the Earth’s landmasses.
continental drift (theory of continental drift) - states that the continents once formed a single land mass,
broke up, and drifted to
their present locations.
continental glacier - large, slowly moving sheets of ice that can cover an entire continent.
continental polar - cold, dry air mass that forms over northern Canada.
continental rise - gently sloping section of the continental margin located between the continental slope and
the abyssal plain.
continental shelf - gently sloping section of the continental margin located between the shoreline and the
continental slope.
continental slope - steeply inclined section of the continental margin located between the continental rise
and the continental shelf.
continental tropical - dry, hot air mass that forms over Mexico in the summer.
contractile vacuole - cell organelle that pumps excess water out of the cell.
control (controlled variable) - standard used for comparison in an experiment; experiment run exactly the
same way as the
experiment with the variable, but the variable is left out.
convection - transfer of heat energy by the circulation or movement of gases or liquids; the movement of
matter due to
differences in density that are caused by temperature variations.
convection current - any movement of mater that results from differences in density; may be vertical,
circular, or cyclical.
convergent boundary - area where two tectonic plates collide.
cooperation - interaction between two or more living things in which they work
together. 5
coral reef - limestone structure built from the shells of coral animals in war, shallow ocean waters.
core - central part of the Earth below the mantle.
Coriolis effect - curving of the path of a moving object from an otherwise straight path due to the Earth’s
rotation.
corona - outermost layer of the sun’s atmosphere.
cosmology - study of the origin, properties, processes, and evolution of the universe.
covalent bond - chemical bond between two atoms of the same or different elements in which each atom
shares an electron.
crater - bowl-shaped depression that forms on the surface of an object when a falling body strikes the
object’s surface or when an
explosion occurs.
crest - highest point of a wave.
crevasse - crack on the surface of a glacier.
crust - thin, solid, outermost layer of the Earth covering the mantle.
cryosphere - frozen part of the Earth’s surface; includes the polar ice caps, continental ice sheets, glaciers,
sea ice, and permafrost.
crystal - natural solid substance that has a definite geometric shape.
crystalline solid - solid made up of crystals.
cumulonimbus cloud - large cloud that produces thunderstorms.
cumulus cloud - puffy cloud with a flat bottom that forms at an altitude of 2.4 to 13.5
kilometers.
cycle - series of events or actions that repeat themselves regularly; a physical and/or chemical process in
which one material
continuously changes locations and/or forms.
cyclic behaviors - innate behaviors, such as migration or hibernation that occur in a repeated pattern, often
in response to changes
in the environment.
cyclone - area in the atmosphere that has lower pressure than the surrounding areas and has winds that spiral
toward the center.
cytoplasm - thick, gelatin-like substance outside the nucleus; holds the organelles.
data table - tool used to display information in rows and columns so that it is easier to read and understand.
datum (plural-data) - recorded observations and measurements; information gathered by observation or
experimentation that can
be used in calculating or reasoning.
day - time required for Earth to rotate once on its axis.
deciduous - trees and shrubs that drop their leaves when winter comes.
decomposer - any organism that feeds or obtains nutrients by breaking down organic matter from dead
organisms.
deep current - stream-like movement of ocean water far below the surface caused by differences in density.
deep-water zone - zone of a lake or pond below the open-water zone, where no light reaches.
deflation - form of wind erosion in which fine, dry soil particles are blown away.
deforestation - removal of trees and other vegetation from an area.
deformation - bending, tilting, and breaking of Earth’s crust; the change in the shape of rock in response to
stress.
dehydration - excessive loss of water.
delta - buildup of sediment deposited in a triangular or fan shape at the mouth of a river or stream.
density - mass per unit volume, or how much mass is contained in a given volume of an object; number of
individuals in the same
species that live in a given area.
deoxyribonucleic acid (DNA) - nucleic acid that stores the information needed to build proteins and carries
genetic information
about an organism; present in all cellular organisms.
dependent variable - factor being measured or observed in an experiment; a factor that responds to, or
depends on, other factors;
factor that changes as a result of manipulation of one or more independent variable. (outcome variable)
deposition - natural process by which sediments are laid down in new locations.
dermis - lower layer of skin.
desalination - process of removing salt from ocean water.
desert - driest biome on Earth; receives less than 25 cm of rain each year and supports little plant life.
desertification - process by which human activities or climatic changes make areas more desertlike.
desert pavement - is a layer of gravel and larger stones left behind when dry winds blow away fine grained
sediments.
desert soil - soil found in dry regions that contains a large quantity of minerals.
destructive boundary - type of plate boundary where plate material is subducted.
development - act, process or result of maturing.
dew point - at constant pressure and water vapor content, the temperature at which the rate of condensation
equals the rate of
evaporation.
diaphragm - muscle at the bottom of the chest that aids in breathing.
dichotomous key - series of questions, each with only two answers, that can be used to help identify an
organisms genus and
differential weathering - process by which softer, less weather resistant rocks wear away at a faster rate
than harder, more
weather resistant rocks do.
diffraction - bending of waves around a barrier (or obstruction) or traveling through an opening.
diffusion - process by which food, oxygen, water and other materials enter and leave a cell through openings
in the cell
membrane; the movement of molecules from where they are crowded to where they are less
crowded. 6
digestion - process by which food is broken down into simpler substances.
digestive system - body system that breaks down the food into simple substances.
dike - narrow, flat formation of igneous rock formed in vertical cracks in the existing rocks.
direct transmission - transmitting disease organisms in which the agent moves immediately from the
infected person to the
susceptible person, as in person-to-person contact.
disease - illness of the body or mind that interferes with a person’s ability to function normally.
dislocation - forcing a bone out of joint.
divergent boundary - type of plate boundary where the plates move apart, such as a midocean ridge.
diversity - quality of having many differences.
divide - boundary between drainage areas that have streams that flow in opposite directions.
division - in the taxonomy of plants, the group smaller than a kingdom but larger than a class.
division of labor - division of the work that keeps an organism alive among the different parts of its body.
doldrums - is the windless zone of the equator.
domain - one of three divisions in a classification system based on different types of cells: archaea, bacteria,
and eukarya.
dome - raised area shaped roughly like the top half of a sphere created by rising magma.
dome mountain - dome that has been worn away in places to form many separate peaks.
dominance - tendency of certain (dominant) alleles to make the expression of their corresponding
(recessive) alleles.
Doppler effect - apparent change in the wavelengths of light that occurs when an object is moving toward or
away from the Earth.
drainage basin - area drained by a main river and its channels.
drainage system - network of rills, gullies, and streams that forms a river.
drumlin - oval-shaped mound of till.
ductility (ductile) - ability of a substance to be pulled into thin strands without breaking.
dune - mound of sand built up by wind.
dwarf planet - celestial body that orbits the sun, is round because of its own gravity, but has not cleared its
orbital path; celestial
body similar to a planet but orbiting in a zone that has many other objects in it.
earthquake - shaking of the ground caused by a sudden release of energy in the Earth’s crust along a fault.
Earth system - all of the nonliving things, living things, and processes that make up the planet Earth,
including the solid Earth, the
hydrosphere, the atmosphere, and the biosphere.
echinoderm - invertebrate sea animal with a spiny skeleton, a water vascular system, and tube feet.
eclipse - total or partial blocking out of the sun or moon by a shadow.
ecological succession - process of gradual change from one community of organisms to another.
ecology - study of how living things interact with each other and their environment.
ecosystem - integrated unit of a biological community, its physical environment, and interactions.
ectotherm - animal whose body temperature changes with environmental conditions.
edema - too much
water.
efficiency - ability of a machine to convert work input to work output; always less than 100 percent in real
machines due to some
loss to friction or heat; a machine’s output work divided by its input work and multiplied by 100.
effort force (Fe) - force applied to a machine.
elastic rebound - sudden return of elastically deformed rock to its undeformed shape.
electromagnet - magnet consisting of a coil of wire wrapped around a core that becomes strongly
magnetized when current flows
electromagnetic radiation - emission and propagation of the entire range of electromagnetic spectrum
including: gamma rays,
x-ray, ultraviolet radiation, visible light, microwaves, and radio waves.
electromagnetic spectrum - arrangement of different forms of light in order of increasing frequency and
decreasing wavelength.
electromagnetic wave - transverse wave that does not need a medium to travel; whose speed in a vacuum is
300 000 km per
second and has varying wavelengths and frequencies; waves generated by the oscillation of a charged
particle and
characterized by periodic variations of electric and magnetic fields.
electron - negatively charged particle that moves around the nucleus of an atom in a region called the
electron cloud.
electron cloud - space in which electrons are most likely to be found.
electron microscope - microscope that uses a beam of electrons to magnify the image of an object.
element - pure substance made up of only one kind of atom that cannot be broken down into simpler
substances by ordinary
level.
elliptical orbit - oval or egg-shaped orbit.
El Nino - disturbance of wind patterns and ocean currents in the Pacific Ocean that causes temporary climate
changes in many
emotion - strong
feeling.
7
empirical evidence - observations, measurement and other types of data that people gather and test to
support and evaluate
endocytosis - into the cell.
endoplasmic reticulum (ER) - maze of clear tubular passageways that leads out from the nuclear
membrane; involved in the
manufacture and transport of proteins.
endoskeleton - internal system of bones that protects and supports an animal’s internal organs and also
provides a place for muscle
attachment; skeleton inside the body.
endospore - oval-shaped structure that protects a bacterium.
endotherm - animal that maintains a constant body temperature.
endothermic reaction - chemical reaction that absorbs energy.
energy - capacity for work; a source of usable power.
energy conversion - change from one form of energy to another.
energy efficiency - measurement of useable energy after an energy conversion; the ratio of useable energy to
the total energy after
an energy conversion.
energy level - most likely location in the electron cloud in which an electron can be found.
energy pyramid - pyramidal diagram that compares the amount of energy available at each position, or
level, in the feeding order;
a model used to show the amount of energy available to living things in an ecosystem.
energy resource - natural resource that humans use to generate energy.
energy transfer - change of energy from one form to another.
engineering - application of science and mathematics to solve real-life problems.
entropy - measure of randomness or disorder of a closed system.
environment - sum of conditions affecting an organism, including all living and nonliving things in an area,
such as plants,
animals, water, soil, weather, landforms, and air.
enzyme - special type of protein that regulates chemical activities within the body.
epicenter - place on the Earth’s surface directly above the focus of an earthquake.
epidermis - outermost layer of the skin.
epiglottis - small flap of tissue that closes over the windpipe.
equator - imaginary line at 0o latitude that circles the Earth halfway between the north and south
geographical poles and divides
the Earth into two equal halves.
equinox - occurs twice yearly when the sun appears to cross the celestial equator, with the result that day and
night are the same
length all over the world; the vernal equinox occurs March 20 or 21 and the autumnal equinox occurs
September 20 or 21.
erosion - process of wearing away of the Earth’s surface by breaking down and carrying away soil, rock, or
sediment by wind,
stomach.
estivation - behavioral adaptation for survival during hot, dry summer months, during which an animal
becomes inactive; in
amphibians, involves hiding in cooler, more humid ground.
estrogen - hormone produced by ovaries; responsible for the development and growth of secondary sex
characteristics in females.
estuary - shoreline area where fresh water from a river mixes with salt water from the ocean.
euglena - microscopic, unicellular Protist that is usually green and moves using a flagellum (pl-flagella.)
Eukarya - domain made up of all eukaryotes.
eukaryotic cell (eukaryotes) - more complex type of cell with a true nucleus. (kingdoms: Protista, Fungi,
Plantae, and Animalia)
eutrophication - increase in the amount of nutrients, such a nitrates, in a marine or aquatic ecosystem.
evaporation - process in which a liquid changes into a gas by absorbing heat energy, usually at the surface.
evaporite - sedimentary rock formed when water evaporates and leaves behind mineral deposits.
evidence - thing or things helpful in forming a conclusion or judgment.
excretion - process of getting rid of waste materials.
excretory system - body system that removes body wastes.
exfoliation - breaking off of pieces of rocks that are parallel to the rock’s surface.
exhale - to breathe out.
exocytosis - out of the cell.
exoskeleton - lightweight body covering that protects and supports an arthropod’s body, prevents it from
drying out, and is shed
by molting; a hard outer covering.
exosphere - upper atmosphere.
exothermic reaction - chemical reaction that releases energy.
experiment - organized procedure that is carried out and repeated under controlled conditions in order to
discover, demonstrate, or
test a hypothesis; includes all components of the scientific method.
experimental bias - error that distorts results in a particular way; something that causes certain outcomes to
be favored over
extended family - parents, children, and other relatives such as grandparents, aunts, uncles, and so forth.
extensor - muscle that straightens a
joint. 8
extinction (extinct) - permanent disappearance of a species.
extrusion - igneous rock formation that forms on the Earth’s surface.
extrusive rock - igneous rock formed from melted rock or lava that cools and hardens at or near the Earth’s
surface.
fact - quality of being real or actual.
family - classification group between order and genus; the oldest and most basic social unit.
fat - energy-rich organic compound made up of carbon, hydrogen and oxygen, that is solid at room
temperature.
fault - crack or break in the Earth’s crust along which one block moves relative to another.
fault-block mountain - mountain formed by a block of rock uplifted by a normal fault.
fermentation - energy-releasing, chemical process in which sugars and starches are changed into alcohol
and carbon dioxide when
no oxygen is present.
fern - seedless, vascular, fringe-leafed plant that grow in cool, wooded environments.
fertilization - joining of egg and sperm to make a new cell.
fiber - structure that resembles a thread; it can be a strand of nerve tissue or a cell that is threadlike.
fibrin - substance that traps blood cells and plasma, forming a scab.
first aid - emergency medical care for someone who has been hurt or who is sick.
first law of thermodynamics - states the internal energy in a system remains constant and the change in
thermal energy of a
system is equal to the work done on the system.
fjord - long, narrow sea inlet that is bordered by steep cliffs.
flagellum (plural-flagella) - whip-like structure that propels some one-celled organisms.
flammability - ability to burn.
flexor - muscle that bends a joint when it contracts.
floodplain - area along a river that forms from sediments deposited when the river overflows its banks.
flower - reproductive structure of an angiosperm, containing male and female parts.
focus (plural-foci or focuses) - point beneath the Earth’s surface where rocks first break and move during an
earthquake.
folding (fold) - bending of rock layers due to stress; (bend in a rock.)
foliated rock - texture of some metamorphic rocks in which mineral crystals are arranged in parallel bands
along which the rocks
tend to break.
food chain - transfer of energy through various stages as a result of feeding patterns of a series of
organisms.
food vacuole - spherical part that forms from pseudopods that engulf and digest captured
food.
food web (food cycle) - interconnected feeding relationships in a food chain found in a particular place and
time.
foot wall - block of rock below a fault.
force - quality that tends to produce movement or acceleration of a body in the direction of its application;
push or a pull; can be
measured by the amount of acceleration it can give a mass; has size and direction.
forest soil - soil that forms under a cover of leaves and other plant remains and contains very little humus.
fossil - remains or traces (whole or part) of past plant and animal life that has been preserved in sedimentary
rock.
fossil fuel - nonrenewable energy resource that began to form millions of years ago from remains of once-
living plants and
animals; provides energy and includes coal, oil, and natural gas.
fossil record - historical sequence of life indicated by fossils found in layers of Earth’s crust.
foster family - child care provided in a family setting by non-biological parents.
fracture - mineral breakage that forms an irregular surface that may be rough or jagged; a bone break.
freezing - change of a liquid to a solid.
freezing point - temperature at which a liquid changes to a solid.
freezing rain - rain that freezes when it hits the ground or another surface and coats the surface with ice.
frequency - number of waves that pass a given point in one second; measured in waves per second, or hertz
(Hz).
friction - force that resists motion between two objects in contact and that always acts opposite to the
direction of motion.
fringing reef - type of coral reef that touches the shoreline of a volcanic island.
front - boundary between air masses of different densities and usually different temperatures.
frost action - mechanical weathering process caused by the repeated freezing and melting of water.
fruit - ripened ovary of a flowering plant that contains the seeds.
fulcrum - pivot point of a lever.
full moon - phase of the moon when the entire lighted side of the moon is visible.
function - special, normal, or proper activity of an organ or part. ( job; what it does; physiology)
Fungus (plural-Fungi) - kingdom made up of multicellular eukaryotic cells that have no movement,
reproduce by spores, and
get food by breaking down substances to absorb the nutrients.
galaxy - large collection of stars, gases, and dust that are part of the universe bound together by gravitational
forces.
gall bladder - organ in the digestive system that stores bile.
gamete - sex cell: the egg or the sperm.
gamma ray - electromagnetic radiation with wavelengths shorter than those of x-rays and having greater
energy and penetrating
gas - phase in which matter has no definite shape or
volume. 9
gas giant - planet that has a deep, massive atmosphere, such as Jupiter, Saturn, Uranus, or Neptune.
gasohol - mixture of gasoline and alcohol that is used as a fuel.
gem - rare, very valuable and beautiful mineral.
gene - specific part of a chromosome or sequence of DNA that determines a particular feature or
characteristic in an organism.
genetic material - nucleic acid (DNA) that is present in all living cells and contains the information needed
for a cell’s growth,
maintenance, and reproduction.
genotype - sum total of the genetic information contained in an organism.
genus (plural-genera) - group of organisms that are closely related; classification group between family and
species.
geocentric - Earth-centered.
geologic column - ordered arrangement of rock layers that is based on the relative ages of the rocks and in
which the oldest rocks
are at the bottom.
geology - study of the Earth’s origin, history, and structure.
geologist - scientist that studies the Earth’s origin, history, and structure.
geosphere - all the features on Earth’s surface and everything below the surface; the mostly solid, rocky part
of the Earth; extends
from the center of the core to the surface of the crust.
geostationary (geosynchronous) orbit - orbit that is about 36 000 km above Earth’s surface and in which a
satellite is above a
fixed spot on the equator; orbit in which a satellite moves at a speed that exactly matches the Earth’s rate of
rotation.
geothermal energy - energy produced from the heat energy within the Earth that can be used to generate
electricity.
germ - microorganism, especially one that causes disease.
germination - beginning of growth of a new plant from a spore or a seed.
gestation - in mammals, the period of time spent by a developing offspring inside the mother’s body.
geyser - natural hot spring that occasionally sprays water and steam above the ground.
giant star - star with a diameter 10 to 100 times as large as the sun.
gill - respiratory organ that filters oxygen dissolved in water.
glacial drift - rock material carried and deposited by glaciers.
glacier - large mass of moving ice and snow that exists year
round.
Global Positioning System (GPS) - determines the position, speed, and direction of a person anywhere on
Earth.
global warming - rise in global temperatures because of the increase of greenhouse gases in the atmosphere.
global wind - wind that travels long distances in steady patterns over several weeks.
globular cluster - stars grouped in huge spherical clusters.
Glossopteris - extinct seed fern that grew about 250 million years ago.
glucose - simple sugar into which all carbohydrates are broken down in the body to produce energy.
Golgi apparatus (body) - secretory structure consisting of a stack of flat sacs that store and convert or
modify proteins.
gram (g) - basic unit of mass in the metric system. (kilogram is commonly used instead of gram)
graph - diagram that shows the relationship; tool used to collect, organize, and summarize data in a visual
way so that it is easy to
use and understand.
grasslands - temperate and tropical regions that receive between 25 cm and 75 cm of precipitation each year
and are dominated by
climax communities of grasses.
grassland soil - very rich, fertile soil that is excellent for growing crops.
gravity - force of attraction between objects that is due to their masses.
greenhouse effect - heat-trapping process in which heat becomes trapped by cloud layers and cannot escape
back into space;
warming of the surface and lower atmosphere of Earth that occurs when water vapor, carbon dioxide, and
other gases
absorb and reradiate thermal energy; prevents Earth from being too cold to support life.
greenhouse gases - gases, such as carbon dioxide and methane, that absorb and give off infrared radiation as
part of the
greenhouse effect.
groundwater - water that soaks into the ground and collects in the small spaces between bits of rock and
soil.
growth - stage in the process of growing; a measure of progressive development.
gulf - part of the ocean that is partly surrounded by water. (larger than a bay)
gullet - funnel-shaped structure in the paramecium and other unicellular organisms.
guyot - flat-topped seamount.
gymnosperm - plant that produces seeds that are not enclosed in flowers or fruit.
habitat - place in an ecosystem where an organism normally lives; the natural environment in which a
living thing gets all that it
needs to live.
hail - layered lumps or balls of ice that fall from cumulonimbus clouds.
half-life - amount of time required for half of an original sample of radioactive material to decay or undergo
radioactive
transformation.
hanging wall - block of rock above a fault.
harbor - sheltered area of water where ships may anchor safely.
hardness - ability of a mineral to resist being scratched.
hard water - water containing large amounts of dissolved minerals.
Haversian canal - passageway running through the thick bone, containing blood vessels and
nerves. 10
heat - transfer of energy from an object with a higher temperature to an object with a lower temperature.
heat of fusion - amount of heat energy required to convert a unit mass of substance from a solid to a
liquid through melting at a
constant temperature and pressure.
heat of vaporization - amount of heat energy needed to change a unit mass of substance from a liquid to a
gas at its boiling point.
heliocentric - sun-centered.
hemoglobin - iron-containing substances in red blood cells.
herbivore - animal that eats only plants.
heredity - passing of genetic traits from parent to offspring.
Hertzsprung-Russell diagram (H-R diagram) - chart of the relationship between the absolute magnitude
and the surface
temperature of stars.
heterotroph - organism that is not able to make its own food and thus feeds on other organisms; consumer.
heterozygous - cell or organism that has two different alleles for a particular trait.
hibernation - behavioral adaptation for survival during cold, winter months, where an animal becomes
inactive and its metabolic
needs are lowered; in amphibians, involves burying themselves in mud or leaves until temperatures become
warmer.
high-pressure system - usually calm and clear weather system that forms when air sinks down and spreads
out toward areas of
lower pressure as it nears the ground.
high tide - bulge in the ocean on the side of the Earth facing the moon and on the opposite side.
hill - raised area or mound of land.
homeostasis - ability of an organism to keep conditions inside its body the same even though conditions in
its external environment change.
homozygous - cell or organism that has identical rather than different alleles for a particular
trait.
horizon - line where the sky and the Earth appear to meet.
hormone - chemical substance made in the body that triggers a specific response, such as growth.
host - organism in which a parasite lives; a person or organism in whom an infectious pathogen can live and
multiply.
host cell - cell that a virus infects and uses to make copies of itself.
hot spot - volcanically active area of Earth’s surface, commonly far from a tectonic plate boundary.
humidity - amount of water vapor in the air.
humus - dark, organic material formed in soil from the decayed remains of plants and animals.
hurricane - large, swirling, low-pressure system that forms over tropical oceans and has winds of at least
120 km per hour.
hydroelectric energy (power) - production of electricity by the flow of water.
hydrosphere - all of the water on the Earth; 97 percent is salt water and only 3 percent is fresh water.
hypha (plural-hyphae) - threadlike tubes that form the structural parts of the body of a fungus.
hypothesis (plural-hypotheses) - suggested solution or prediction to a scientific problem; “educated” guess;
testable idea or
explanation that leads to scientific investigation.
ice age - period of time during which surface temperatures drop significantly and huge ice sheets spread out
beyond the polar
regions.
ice core - long cylinder of ice obtained from drilling through ice caps or ice sheets; used to study past
climates.
igneous rock - type of rock formed from cooled and hardened magma or lava.
immune system - human body’s network of cells and organs that produce disease-fighting antibodies.
immunity - body’s ability to resist infection.
impermeable membrane - when materials will not pass through a membrane.
imprinting - type of learning in which an animal forms a social attachment to another organism soon after
birth or hatching.
inclined plane - simple machine that uses a slanted surface that makes it easier to move a mass from a lower
point to a higher
point; allows heavy loads to be lifted by using less force over a greater distance.
incubation - process of keeping eggs warm by bodily heat until they hatch.
incubation period - time between contact with a source of infection and the outbreak of symptoms.
independent variable - one factor changed by the person doing the experiment in order to study changes in
the dependent
variable; factor that is deliberately manipulated. (test variable)
index fossil - fossil that is used to establish the age of a rock layer because the fossil is distinct, abundant,
and widespread and the
species that formed the fossil existed for only a short span of geologic time.
indicator - chemical compound that changes color depending on the pH of the solution or other chemical
change.
indirect transmission - transmitting disease organisms in which the agents do not pass directly from an
infected person to a
susceptible person but by means of an intermediate host.
inertia - property of a mass to resist changes in motion; measure of an object’s ability to remain at rest or to
keep moving unless
infection - invasion of the body by organisms.
infectious disease - disease caused by microorganisms living in or on the body.
inference (infer) - conclusion based on an observation.
infiltration - process in which water soaks into the soil.
infrared radiation - invisible heat energy from the sun.
ingestion -
eating.
11
inhale - to breathe in.
inlet - small part of a body of water that reaches into a coast.
innate behavior - behavior that an animal is born with and does not have to learn.
inner core - solid, innermost layer of the Earth.
inorganic - composed of material that is not and never was living.
inorganic compound - compound that does not usually contain the element carbon.
insect - arthropod with three body segments, six legs, two antennae, and compound eyes.
instinct - complex pattern of innate behavior.
insulation - substance that reduces the transfer of electricity, heat, or sound.
interaction - condition of acting or having an influence upon something.
interference - ability of two or more waves to combine and form a new wave when they overlap; can be
constructive, forming a
larger wave, or destructive, forming a smaller wave.
International Date Line - transition line for calendar days, located at the 180o meridian (longitude).
International System of Units (SI) - system of units used in science; metric system.
intertidal zone - portion of the shoreline that is covered with water at high tide and exposed to the air at low
tide.
intrusion - igneous rock formed when magma forces its way into sedimentary rock and hardens below or on
the Earth’s surface.
intrusive rock - rock that forms from melted rock or magma that cools and hardens deep below the Earth’s
surface.
invertebrate - animal without a backbone; about 97 percent of animals are invertebrates.
investigation - procedure that is carried out in order to observe a response caused by a stimulus; not a
complete experiment.
atom.
ionosphere - layer of electrically charged particles in the thermosphere.
island - piece of land that is surrounded by water.
isobar - line on a weather map connecting places that have the same air pressure.
isotherm - line on a weather map connecting locations that have the same temperature.
isostasy - balance between the downward force of the crust and the upward force of the mantle.
isotope - atom of a substance that has the same number of protons but a different number of neutrons as
another atom of the same
substance.
isthmus - narrow strip of land connecting two larger landmasses. (has water on two sides)
jet stream - narrow belt of strong winds that flows from west to east at great speeds near the top of the
troposphere.
joint - crack in the crustal rock; a place where bones meet.
Kelvin (K) - temperature scale (SI unit) that has its zero at absolute zero where matter stops moving; water
freezes at 273.15o and
boils at 373.15o.
kettle lake - bowl-shaped lake that was formed as sediment built up around a block of ice left behind by a
glacier.
kilogram - see gram.
kinetic energy - energy possessed by a body because of its motion.
kingdom - largest classification grouping.
Kuiper Belt - region of the solar system that is just beyond the orbit of Neptune and that contains small
bodies made mostly of ice.
Kuiper Belt object - one of the hundreds or thousands of minor planet-sized objects that orbit the sun in a
flat belt beyond
Neptune’s orbit.
laccolith - dome-like intrusion that pushes overlying rocks into an arch and has a flat floor.
lake - filled or partially filled basin of fresh or salt water surrounded by land.
land breezes - nightly movements of air created when cold air over the land forces up the warmer air above
the sea.
land degradation - process by which human activity and natural processes damage land to the point that it
can no longer support
landslide - sudden movement of rock and soil down a slope.
La Nina - change in the eastern Pacific Ocean in which the surface water temperature becomes unusually
cool.
large intestine - organ in the digestive system in which water is absorbed and undigested food is stored.
larva (plural-larvae) - free-living early form of a developing organism that is very different from its adult
form.
larynx - voice box.
lateral fault - crack along which the blocks of rock move horizontally past one another.
lateral moraine - till deposited along the sides of a glacier.
latitude - measure of distance in degrees north or south of the equator.
launch - process of setting a rocket or spacecraft in motion.
lava - hot, molten rock that has reached the Earth’s surface.
lava plateau - layers of lava that build up on a flat area on the Earth’s surface.
law - rule or principle describing a physical relationship that always works in the same way under the same
conditions; descriptive
statement or equation that reliably predicts events under certain conditions.
law of conservation of energy - states that no matter how energy is transferred or transformed, all of the
energy is still present in
one form or another.
law of conservation of matter - states that matter is neither created nor destroyed, only changed in
form. 12
law of definite proportions - states that a given compound is always made of the same elements in the same
proportion by mass.
law of electric charges - states that like charges repel and opposite charges attract.
law of inertia - states that an object’s motion will not change unless that object is acted on by an outside
force.
law of superposition - states that in layers of sedimentary rocks, younger rocks normally lie on top of older
rocks if the layers
have not been disturbed.
leaching - removal of substances that can be dissolved from rock, ore, or layers of soil due to the passing of
water.
legend - key that explains what symbols on a map represent.
lens - curved pieces of glass that bend light rays as they pass through it.
levee - ridgelike deposit of sediments on a flood plain.
lever - simple machine made from a rod or plank that pivots about a point (fulcrum); used to transmit and
enhance power or
motion.
lichen - organism made up of a fungus and a green alga.
life cycle - entire sequence of events in an organism’s growth and development.
life span - maximum length of time a particular organism can be expected to live.
life zone - narrow region of space around a star in which a planet that contains life can exist.
ligament - strong, stringy connective tissue that fastens the bones together in a moveable joint.
light - electromagnetic radiation that lies within the visible range.
lightning - electric discharge that takes place between two oppositely charged surfaces, such as between a
cloud and the ground,
between two clouds, or between two parts of the same cloud.
light-year - distance light travels in one year. (about 9.46 trillion km)
lignite - soft, brown coal with a woody texture.
limiting factor - factor or condition that prevents the continuing growth of a population in an ecosystem.
line graph - tool used to show the relationship between two variables.
lipids - include fats, oils, or waxes used for energy or as structural materials that do not dissolve in water.
liquid - phase in which matter has no definite shape but does have a definite volume.
liter (L) - basic unit of volume in the metric
system.
lithosphere - topmost, solid part of the Earth.
littoral zone - shallow zone of a lake or pond where light reaches the bottom and nurtures plants.
liver - organ that produces bile.
load - materials carried by a stream.
local wind - movement of air over short distances; occurs in specific areas as a rest of certain geographical
features.
loess - many layers of fine sand and silt deposited by wind in the same area.
longitude - measure of distance east and west of the prime meridian.
longitudinal wave - particles of the medium vibrate in the direction of the moving energy; the type of wave
made by sound
energy; L wave.
longshore current - overall direction and movement of water as waves strike the shore at an angle.
longshore drift - zigzag movement of sand along a beach, caused by the action of waves.
love - deep, tender feeling of affection and emotional attachment.
low Earth orbit - orbit that is less than 1 500 km above Earth’s surface.
low-pressure system - large and often stormy weather system that forms when air circles, then moves up to
higher altitudes.
low tide - lowest level of the ocean that occurs between the two high tides.
luminosity - actual brightness of an object such as a star.
lunar eclipse - eclipse that occurs when the Earth comes directly between the sun and the full moon.
lunar phases - different appearances of the moon from Earth throughout the month.
lung - respiratory organ that absorbs oxygen from the air.
luster - way a mineral reflects light.
L wave - surface wave.
lysosome - small, round structure involved with the digestive activities of a cell.
machine - any device that makes doing work easier.
magma - hot, molten rock deep inside the Earth.
magma chamber - body of molten rock that feeds a volcano.
magnet - any material that attracts iron or materials containing iron.
magnetic - having the property of attracting iron and certain other materials by virtue of a surrounding field
of force.
magnetic field - region where magnetic force exists around magnets or electric currents.
magnetic pole - one of two points, such as the ends of a magnet, that have opposing magnetic qualities.
magnetosphere - magnetic field of a planet.
magnitude - measure of a star’s brightness.
main-sequence star - star located in an area that runs from the upper left to the lower right of the
Hertzsprung-Russell diagram.
malleability (malleable) - ability of a substance to be hammered into thin sheets without
breaking.
mammal - warm-blooded vertebrate animal whose young feed on milk produced by the mother’s mammary
glands.
mantle - layer of rock between the Earth’s crust and core.
maria - dark, broad, smooth, lowland area on the
moon. 13
marine climate - climate influenced by a nearby ocean, with generally mild temperatures and steady
precipitation.
maritime polar - air mass that forms over the Pacific Ocean and brings cool air in the summer and heavy
snow in the winter.
maritime tropical - warm, moist air mass that forms over the ocean near the equator.
marrow - soft tissue filling the ends and inner spaces of bones.
mass - measure of the amount of matter in an object.
mass number - sum of the protons and the neutrons in the nucleus of an atom.
material resource - natural resource that humans use to make objects or to consume as food and drink.
mass wasting - downhill movement of loose rock or soil.
matter - anything that has mass and volume. (gas, liquid, or solid)
maturation - emergence of personal and behavioral characteristics through growth processes.
mature river - river that has been developing for thousands of years.
meanders - loop in a river.
measurement - way to describe the world with numbers; can describe objects and events with length,
volume, mass, temperature, and rates.
mechanical advantage (M.A.) - comparison of the effort force to the resistance for a machine; output force
divided by input force.
mechanical digestion - physical action of breaking foods into smaller parts.
mechanical energy - amount of work an object can do because of the object’s kinetic and potential energies.
mechanical wave - wave that can travel only through matter; can be either a transverse or a compressional
wave.
mechanical weathering - process by which rocks break down by natural processes and do not change the
chemical
composition of the rock material. (physical weathering)
medium - material through which a wave travels. (gas, liquid, or solid)
meiosis - form of cell division that halves the number of chromosomes in a male and female sex cell as they
form.
melting - change of a solid to a liquid.
melting point - temperature at which a solid changes to a liquid.
meltwater - stream of water formed by the melting of ice as a valley glacier
moves.
membrane - thin layer of tissue that surrounds or lines a cell, a group of cells, or a cavity; any barrier
separating two fluids.
meniscus - surface of a liquid.
Mercator projection - map projection that has correct shapes of continents, but their areas are distorted; has
lines of longitude
drawn parallel to each other.
meridian - imaginary line used to measure longitude that runs north and south between the Earth’s
geographic poles.
Mesosaurus - extinct reptile that swam in freshwater ponds, lakes, and rivers.
mesosphere - layer of the atmosphere between the stratosphere and the thermosphere and in which
temperature decreases as
altitude increases; strong, lower part of the mantle between the asthenosphere and the outer core.
mesa - land formation with a flat area on top and steep walls. (usually in dry areas)
metabolism - all chemical activities in an organism essential to life.
metal - element that is a good conductor of heat and electricity, is shiny, has a high melting point, is ductile
and malleable and
forms positive ions.
metalloids - elements that have characteristics of both metals and nonmetals, generally are brittle and dull,
and are poor
conductors of heat and electricity.
metamorphic rock - type of rock changed by intense heat, pressure or chemical processes.
metamorphism - changing of one type of rock into another as a result of tremendous heat, great pressure or
chemical reactions.
metamorphosis - developmental process in which an animal changes drastically in body form between the
juvenile and the adult;
can be complete (egg, larva, pupa, and adult) or incomplete (egg, nymph, and adult).
metazoan - multicellular animals that cause scabies and pubic lice.
meteor - bright streak of light produced by a burning meteoroid in Earth’s atmosphere.
meteorite - chunks of rock that strike the Earth’s surface.
meteoroid - relatively small, rocky body that travels through space.
meteorologist - scientist who studies weather.
meteorology - study of the Earth’s atmosphere, weather, and climate.
meter (m) - basic unit of length in the metric system.
methanogen - Archaea that produce methane as a waste product of metabolism.
metric system - universal system of measurement.
microbiology - study of microorganisms.
microclimate - climate of a smaller area within a subclimate.
microorganism - very small organism that can be seen only with a microscope.
microscope - instrument that produces an enlarged image of an object.
microscopic - relating to an object too small to be visible without the use of a microscope.
microwave - high frequency electromagnetic wave used to cook or heat food.
mid-ocean ridge - continuous, seismic mountain range extending across the floor of the world’s major
oceans; area where two
oceanic plates are moving away from each other; area where new crustal material may be released.
migration - instinctive seasonal movement of animals, usually to find food or to reproduce in a better
environment. 14
Milky Way - galaxy in which the Earth’s solar system is
located.
mineral - naturally occurring, inorganic solid that has a definite chemical composition and crystal shape.
mitochondrion (plural-mitochondria) - oval-shaped organelle that is referred to as the powerhouse of a
cell.
mitosis - duplication and division of the nucleus and of the chromosomes during cell reproduction; a process
of nuclear division in
cells during which the number of chromosomes is reduced by half.
mixture - two or more pure substances that are mixed but not chemically combined.
mobile - able to move from place to place.
model - pattern, plan, representation, or description designed to show the structure or workings of an object,
system, or concept.
Moho - boundary between the Earth’s outermost layer and the mantle.
Mohs hardness scale - scale used to determine the hardness of a mineral.
mold - fossil formed in a rock by a dissolved organism that leaves an empty space, showing its outward
shape.
molecule - smallest particle of a substance that has all the physical and chemical properties of that substance;
made up of two or
more atoms that are chemically bonded.
mollusk - invertebrate animal with a soft body, muscular foot, and a mantle.
molting - process of an arthropod shedding its exoskeleton to allow for growth.
momentum - vector quantity that is the product of an object’s mass and velocity; the general effect of
ongoing motion.
month - division of the year that is based on the orbit of the moon around the Earth.
monsoon - major seasonal land and sea breeze; a wind that changes direction with the seasons.
moon - natural satellite that revolves around a planet.
moon phase - fraction of the moon’s disc that is illuminated as seen from Earth; (the eight moon
phases: new moon, waxing-crescent, first quarter, waxing-gibbous, full moon, waning-gibbous, last
quarter, waning-crescent.)
glacier.
moss - seedless, nonvascular, small, grass-like plant that live in moist, cool environments.
motion - change of position over time.
mountain - area of significantly increased elevation on Earth’s surface, usually rising to a summit.
mountain soil - soil found on the slopes of mountain ranges that contains very small amounts of clay and
sand and often no
muck fire - fire that burns organic material in the soil.
mudflow - flow of a mass of mud or rock and soil mixed with a large amount of water.
multicellular - having many cells.
muscle - tissue that has the ability to contract or shorten; a special tissue that causes movement.
muscle strain - problem that occurs when a muscle is overused after it has not been exercised for several
weeks.
muscle tear - separating of the fibers of a muscle by sudden force or stretching.
mutation - process by which a gene undergoes a change in DNA sequence or a structural change.
mutualism - interaction between two species in which both benefit.
nanotechnology - study of the science and technology of building electronic circuits and devices from single
atoms and
NASA - National Aeronautics and Space Administration.
natural gas - mixture of gaseous hydrocarbons located under the surface of the earth, often near petroleum
deposits; used as a
fuel.
natural resource - any type of matter or energy from Earth’s environment that humans use to meet their
needs; includes water,
natural selection - theory stating every organism displays slight variations from other organisms of its kind,
and the struggle for
limited natural resources results in individuals with certain natural variations adapted to their
specific environments.
neap tide - high tide lower than usual during first and third quarter moons; a twice-monthly tide of minimal
range that occurs
when the sun, moon, and Earth are at right angles to each other, thus decreasing the total tidal force
exerted on Earth.
nebula - massive cloud of dust and gas in which stars are probably born.
nebular theory - idea that the solar system began in a vast gas cloud.
nekton - all organisms that swim actively in open water, independent of currents.
nephron - microscopic chemical filtering factory in the kidneys.
neritic zone - ocean area that extends from the low tide line to the end of a continental shelf.
net force - combination of all of the forces acting on an object.
neutral - particle, object, or system that lacks a net charge.
neutron - electrically neutral particle found in the nucleus of an atom.
neutron star - rapidly spinning core of a massive star that remains after a supernova explosion.
new moon - phase of the moon when it is not visible in the sky.
Newton (N) - SI unit for force.
Newton’s laws of motion - three rules describing how things move—an object will move with constant
motion if no net force is
acting on it; an object that has an unbalanced force acting on it will accelerate in the direction of
the force; and forces
occur in equal but opposite pairs.
niche - unique position occupied by a particular species in terms of the area it inhabits and the function it
performs within the
nitrogen cycle - continuous movement of nitrogen through Earth, its atmosphere, and the living things on
Earth.
nodule - potato-sized lump of mineral on the ocean floor.
non-communicable - illness that is not caused by a disease-causing organism; a non-infectious disease.
nonmetal - element that is a poor conductor of heat and electricity, has a dull surface, low melting point, is
brittle, breaks easily
and forms negative ions.
non-point source - pollution that comes from many different sources, such as industries, homes, and
farms.
nonrenewable resource - any resource that cannot be replaced by nature, such as fossil fuels and minerals;
resource that forms at a rate that is much slower than the rate at which the resource is consumed.
nonvascular plant - plant lacking vascular tissue and that absorbs water and other dissolved substances
directly through its cell walls.
normal fault - crack formed when the hanging wall moves down relative to the foot wall.
normal force - upward force of the ground, perpendicular to the surface.
nostril - opening in the nose.
nova - star that suddenly increases in brightness.
nuclear energy - energy locked within the atomic nucleus; the energy released by a fission or fusion
reaction.
nuclear family - parents and their children.
nuclear fission - splitting of an atomic nucleus into two smaller nuclei during which vast amounts of energy
is released.
nuclear fusion - combining two lighter atomic nuclei to form heavier elements which produce large amounts
of energy.
nuclear membrane - thin membrane that separates the nucleus from the protoplasm of the cell.
nucleic acid - large organic compound that stores information that helps the body make the proteins it needs.
nucleolus (plural-nucleoli) - cell structure located in the nucleus and made up of RNA and protein; may
play important role in
nucleus (plural-nuclei) - spherical organelle in eukaryotic cells that contains the genetic material and directs
all the activities of
the cell; positively charged center of an atom containing most of the mass.
nutrient - useable portion of food; a substance that an organism needs to live.
objective - not influenced by emotions or personal prejudices, nor particular to one person.
observation - process of obtaining information by using the senses.
occluded front - type of front that occurs when a cold front overtakes a warm front, pushes it upward, and
meets cool air.
ocean - large body of salt water that surrounds a continent.
ocean basin - depression of the surface of Earth occupied by water.
ocean crust - section of the Earth’s crust under the ocean floor.
ocean current - movement of ocean water that follows a regular pattern.
ocean-floor spreading - process in which the ocean floor on either side of a rift valley is pushed away by
lava erupting from the
oceanographer - scientist who studies the ocean.
oceanography - study of the Earth’s oceans, including their physical features, life forms, and natural
resources.
oil - energy-rich organic compound made up of carbon, hydrogen and oxygen that is liquid at room
temperature.
omnivore - animals that eat both plants and animals.
Oort cloud - spherical region that surrounds the solar system, that extends from the Kuiper Belt to almost
halfway to the nearest
star and that contains billions of comets.
open cluster - group of stars that are close together relative to surrounding stars.
open-water zone - zone of a pond or lake that extends from the littoral zone and that is only as deep as light
can reach.
oral groove - mouth-like indentation in a paramecium and other unicellular organisms.
orbit - path one object takes when moving around another object in space.
order - classification group between class and family.
ore - rock from which metals and other minerals can be removed in usable amounts.
organ - group of different tissues working together.
organelle - parts that make up a cell.
organic - composed of material that is or was living.
organic compound - compound that contains the element carbon.
organic rock - sedimentary rock built up from the remains of living things.
organism - entire living thing made up of one or more cells that carries out all the basic life functions.
organ system (system) - organs that work together to perform certain functions.
osmosis - movement of water through a cell membrane.
outcome variable - factor being measured or observed in an experiment; a factor that responds to, or
depends on, other factors.
(dependent variable)
outer core - liquid layer of the Earth surrounding the inner core.
outwash plain - sediments deposited by rivers of glacial meltwater in a fan-shaped area in front of a terminal
moraine.
ovary - enlarged base of the pistil that holds the ovule.
ovule - organ that produces and holds the eggs in a
flower. 16
oxbow lake - small lake formed when a bend in a river is cut off from the river.
oxidation - process in which oxygen chemically combines with another substance.
ozone (O3) - gas molecule that consists of three oxygen atoms.
ozone layer - stratospheric layer with a high concentration of ozone; protects Earth by absorbing harmful
ultraviolet radiation.
pacemaker - controls the pace at which the heart beats.
paleontologist - scientist who uses the remains or traces of long-dead organisms to form a picture of the
Earth’s past.
pancreas - gland that produces pancreatic juice and insulin.
Pangaea - one large landmass of which all the continents were once a part according to the theory of
continental drift.
parallax - apparent change in the position of an object when viewed from different locations.
parallel - imaginary line used to measure latitude that runs east and west around the Earth.
paramecium (pl-paramecia) - microscopic, unicellular Protist that move by means of cilium (pl-cilia.)
parasite - organism that feeds on other living organisms often harming them in the process.
parasitism - relationship between two species in which one species is harmed while the other benefits.
parent rock - rock formation that is the source of soil.
particle - very small piece of matter such as an atom, molecule, or ion.
particulate - tiny particle or droplet, such as dust, dirt, or pollen that are mixed in with
air.
pathogen - specific cause of disease. (EX-bacteria or virus)
passive transport - movement of materials through a membrane without any input of energy.
peat - soft substance made of decayed plant fiber; softest type of coal.
peer pressure - process by which a person feels forced to do what others want them to do.
pelagic environment - in the ocean, the zone near the surface or at middle depths, beyond the sublittoral
zone and above the
abyssal zone.
peninsula - body of land that is surrounded by water on three sides.
penumbra - outer area of a shadow cast by an object in space onto another object in space in which the light
is only partly blocked.
percolation - movement of water through rock or soil.
perigee - point of the moon’s orbit closest to the Earth.
perihelion - point in the orbit of a planet at which the planet is closest to the sun.
periodic - describes something that occurs or repeats at regular intervals.
periosteum - tough membrane surrounding a long bone.
peristalsis - powerful waves of muscle contractions that push the food through the digestive system.
permeability - capability of a porous substance or membrane to allow a fluid or gas to enter it; the measure
or degree to which a
substance can be penetrated by a liquid or gas.
permeable membrane - when materials will pass through a membrane.
petal - colorful blades that surround the inner parts o