6 grade science vocabulary words

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

quickly respond to their environment.

anion - atom that has gained electrons; a negative ion.

anther - part of the stamen that produces

pollen.

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anthracite - hard, brittle coal that is almost pure carbon.

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

element's placement on the periodic table.

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

numerical data.

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.

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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. boiling point - temperature at which a liquid boils. 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.

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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

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