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exam flashcards
science
104
Science
8th Grade
12/15/2005

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Term
apparent magnitude
Definition
the brightness of a star as seen from earth
Term
Bing Bang
Definition
the initial explosion that, according to theory resulted in the formation and expansion of the universe
Term
Binary star
Definition
a star system that contains two stars
Term
Black hole
Definition
the remains of an extermely massice star pulled into a samll volume by the force of gravity.
Term
constellation
Definition
a pattern of stars in the sky.
Term
elliptical galaxy
Definition
a galaxy shaped like a falttened ball tat can cantain mostly old stars.
Term
galaxy
Definition
a giant structure that contains dust,gases,and hundereds of billions of stars.
Term
giant star
Definition
a very large star, much larger than the sun
Term
giant star
Definition
a very large star, much larger than the sun
Term
irregular galaxy
Definition
a galaxy that does not have a regualr shape
Term
Light-year
Definition
the distance that light travels in one year.
Term
Nebula
Definition
a large amount of gas and dust in space spread out in an immense volume.
Term
Neutron star
Definition
a tiny star that remanins after a supernova explosion
Term
observatory
Definition
a building that contains one or more telescopes
Term
parallax
Definition
the apparent change in position of an object when seen from different places
Term
protostar
Definition
a contracting could of gas and dust, the earliest stage of a stars life
Term
pulstar
Definition
a neutron star that produces radio waves
Term
quasar
Definition
a distant galaxy witha black hole at its center
Term
spectograph
Definition
an instrument that breaks the lgiht from one object into colors that photographs the resulting spectrum.
Term
spiral galaxy
Definition
a galaxy whose arms curve outward in a pinwheel pattern
Term
supernova
Definition
the explosion of a dying giant or supergiant star
Term
universe
Definition
all of space and everything in it
Term
white drawf
Definition
the remaining hot core of a star after its outer layers have expanded and drifted out into space
Term
element
Definition
a substance that cannot be broken down into any other substances by chemical or physical means
Term
atom
Definition
the smallest particle of an element
Term
nucleus
Definition
the control center of the cell that directs the cells activities and determines the cells characteristcs; also the central core of and atom containing protons and usually neutrons
Term
proton
Definition
a small positively charged particle in the nucleus of an atom
Term
neutron
Definition
small uncharged particle in the neucleus of an atom
Term
electron
Definition
a tiny negatively chraged, high-energy particle that moves in the spcae outside the neucleus of an atom
Term
atomic number
Definition
the number of protons in the neucleus of an atom
Term
atomic mass
Definition
the average mass of one atom of an element
Term
valence electron
Definition
the electrons that are farthest away from or most loosly held or by the neucleus of an atom and are involved in chemical reactions
Term
chemical bond
Definition
the force that holds two atoms together
Term
electron dot diagram
Definition
a representation of the number of valence electrons in an atom, using dots placed around the symbol of an element
Term
periodic table
Definition
an arrangement of the elements in order of atomic number numbers in which elements w. similar proerties are grouped in columns
Term
group
Definition
elements in the same vertical column of the periodic table;also called a family
Term
period
Definition
a horizontal row of elements in the periodic table
Term
metal
Definition
an element that easily gives up its valence electron in a chemical reaction and that can be classified based on physical properties (such as hardness,shininess,ease of maleability and ductility)
Term
nonmetal
Definition
an element that lacks most of its properties of metals
Term
metalloid
Definition
and element taht has some of the characteristics of metals and some of the chracteristics of nonmetals
Term
chemical reaction
Definition
a process in which substances undergo chemical changes
Term
precipitate
Definition
a solid that forms from a solution during a chemical reaction
Term
endothermic reaction
Definition
a reaction that absorbs energy in the form of hear
Term
exothermic reaction
Definition
a reaction that reeases energy in the form of hear
Term
molecule
Definition
a combination or two or more atoms that are bonded together
Term
compound
Definition
a substance made of two or more substances that creates a new material
Term
chemical equation
Definition
a short, easy way to show a chemical reaction, using symbols instead of words
Term
formula
Definition
a combination of symbols that shows the ratio of the elements in a compound
Term
subscript
Definition
a number in a chemical formula that tells the number of atoms in a molecule or that ratio of elements in a compound
Term
reactants
Definition
a substance that enters into a chemical reaction
Term
products
Definition
a substance formed as a result of a chemical reaction
Term
conservation of mass
Definition
the principle stating that matter is neither created nor destroyed during a chemical reaction
Term
coefficient
Definition
a number placed in front of a chemical formula in an equation that indicates how many atoms or molecules of each reactant and product take part in the reaction
Term
synthesis
Definition
a chemical reaction in which two or more simple substances combine to form a new more complex substance
Term
decomposition
Definition
a chemical reaction that breaks down a compound into simpler products
Term
replacement
Definition
a reaction in which one element replaces another in a compound or in which two elements in different compounds trade places
Term
activation energy
Definition
the minimum amount of energy needed to start a chemical reaction
Term
concentration
Definition
the amount of one material dissolved in a given amount of another material
Term
catalyst
Definition
a material that increases the rate of a chemical reaction by lowering the activation energy
Term
enzyme
Definition
a biological catalyst that lowers the activation energy of reactions in cells
Term
inhibitor
Definition
a material that decreases tha rate of a reaction
Term
polymer
Definition
a large complex molecule built from smaller molecules bonded together
Term
monomer
Definition
small carbon-based molecules that make up the links in a polymer chain
Term
plastic
Definition
a synthetic polymer that can be molded or shaped
Term
composite
Definition
a combination of two or more substances that creates a new material
Term
alloy
Definition
a mixture made of two or more elements, at least one of which is a metal, that has the properties of a metal
Term
ceramic
Definition
a hard crystalline solid made by heating clay and other materials to high temp.
Term
glass
Definition
a clear, solid material w. no crystal structure, created by heating sandto a cery high temperature
Term
obtical fiber
Definition
long thin strand of glass or plastic or plastic that can carry light for long distances w/o allowing the light to fade out; can be used for tansmitting messages
Term
isotope
Definition
an atom w. the same number of protons and different number or neutrons from other atoms of the same element
Term
radioactive decay
Definition
the proces in which the atomic nucli of unstable isotopes release fast-moving paritlcles and energy
Term
neuclear reaction
Definition
a reaction involving the praticles in the nucleus of an atom that can change one element into another element
Term
alpha particle
Definition
a form of neuclear radiation consisting of two protons and two neutrons
Term
beta particle
Definition
a electron that is given off by its neucleus during radioactive decay
Term
gamma radiation
Definition
a form of neclear radiation consisting of high-energy waves
Term
half-life
Definition
the length of time needed for half of the atoms of a radioactive isotope to decay
Term
radioactive dating
Definition
the process of determination the age of an object using the half-life of one or more radioactive isotoeps
Term
tracer
Definition
a radioactive isotope that can be followed through the steps of a chemical reaction or industrial process
Term
radiation therapy
Definition
a process in which radioactive elements are used to destroy unhealthy cells.
Term
trait
Definition
a characteristc that an organisim can pass on to its offspring thorugh its genes
Term
heredity
Definition
the passing of traits from parents to offspring
Term
gene
Definition
a segment of DNA on a choromosome that codes for a specific trait
Term
purebred
Definition
an organism that always produces offspring w. the same form of a trait as itself
Term
allele
Definition
the different forms of a gene
Term
dominant allele
Definition
an allele whose trait always shows up in the organism when the allele is present
Term
recessive allele
Definition
an allele that is masked when a dominant allele is present
Term
hybrid
Definition
an organism that has two different alleles for a trait; an organism that is heterozygus for a particular trait
Term
probability
Definition
the liklihood that a particular event will occur
Term
phenotype
Definition
an organisms physical appearence or visible traits
Term
genotype
Definition
an organisms genitic makeup makeup; or allele combinations
Term
heterozygous
Definition
having two different alleles for a trair
Term
homozygous
Definition
having two identical alleles for a trait
Term
codminance
Definition
a condition in which neither of two alleles of a gene is dominant or recessive
Term
multiple alleles
Definition
three or more forms of a gene that code for a single trait
Term
sex-linked gene
Definition
a gene carried on the X and Y chromosome
Term
carrier
Definition
a person who has one recessive allele for a trait one one dominant allele, but does not have a trait
Term
pedigree
Definition
a chart, or family tree, that tracks which members of a family have a particular trait
Term
genetic disorder
Definition
an abnormal condition that a person inherits through genes or chromosomes
Term
amniocentesis
Definition
a technique by which a samll amount of the fluid that surrounds a developing baby is removed; the fluid is analyzed to dertermine whether the baby will have a genetic diorder
Term
karyotype
Definition
a picture of all the chromosomes in a cell arranged in pairs
Term
selective breeding
Definition
the process of selecting a few organisms w. desired traits to serve as parents of the next generation
Term
inbreeding
Definition
a selective breeding method in which two individuals w. identical or similar sets of alleles are crossed
Term
hybridzation
Definition
a selective breeding method in which two genetically different individuals are crossed
Term
clone
Definition
an organism that is geneetically identical to the organism from which it was produced
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