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Changes Over Time

Chapter 5 - Cells and Heredity

species a group of similar organisms that can mate with each other and produce fertile offspring.
evolution The gradual change in a species over time.
adaptation A trait that helps an organism survive and reproduce.
scientific theory a well-tested concept that explains a wide range of observations.
natural selection the process by which individuals that are better adapted to their environment are more likely to survive and reproduce thatn other memebers of the same species.
variation any difference between individuals ot the same species.
fossil the preserved remains or traces of an organism that lived in the past.
sedimentary rock rock formed when layers of sediments harded onver millions of years.
petrified rock a fossil formed when minerals replace all or part of an organism.
mold a type of fossil formed when a shell or other hard part of an organism dissolves, leaving an empty space in the shape of the part.
cast a type of fossil that forms when a mold becomes filled in whith minerals that then harden.
relative dating a technique used to determine whcih of two fossils is older.
absolute dating a technique used to determine the actual age of a fossil.
radioactive element An unstable particle that breaks down into a different element.
half-life the time it takes for half of the atoms in a radioactive element to break down.
fossil record the millions of fossils that scientists have collected.
extinct a species that does not have any living members.
gradualism the theory that eveolution occurs slowly but steadily
punctuated equilibria the theory that species evolve during short periods of rapid change.
homologous structure body parts that are structurally similar in related species; provide evidence that the structures were inherited from a common ancestor.
branching tree a diagram that shows how scientists think different groups of organisms are related.
Created by: melaniebird