Download Evolution Change Over Time Unit Summary

Evolution/Change Over Time

Mutation: any change in the DNA of a gene or chromosome
Mutations can cause a cell to produce an incorrect protein during protein synthesis. As a result, the
organism’s trait may be different from what it normally would be.

Cancer: a disease in which cells grow and divide uncontrollably, damaging the parts of the body around them
Cancer begins when mutations disrupt the normal cell cycle, causing cells to divide in an uncontrolled way.
In time, these cells can form a tumor: a mass of abnormal cells.






Species: a group of similar organisms that can mate and produce fertile offspring
Fossil: the preserved remains or traces of an organism that lived in the past
Adaptation: a trait that increases an organism’s ability to survive and reproduce (i.e. beak shape, claw size,
coat color)
Evolution: process by which populations accumulate inherited changes over time.
Scientific Theory: a well-tested concept that explains a wide range of observations.
Artificial selection: process in which only organisms with a desired characteristic are chosen to reproduce
(i.e. domesticated animals and produce)
Darwin hypothesized that species change over many generations and become better adapted to new
conditions.

Natural Selection: the process by which individuals that are better adapted to their environment are more likely to
survive and reproduce more than other members of the same species
o Overproduction: most species produce more offspring than can possibly survive
o Variation: any difference between individuals of the same species
o Competition: Food space and other resources are limited; members of a species must compete with one
other to survive; competition is usually indirect
o Selection: some variations make individuals better adapted to their environment; those individuals are
more likely to survive and reproduce – their offspring may inherit the helpful characteristic; after
many generations, more members of the species will have the helpful characteristic.
Darwin proposed that, over a long time, natural selection can lead to change. Helpful variations may
accumulate in a species, while unfavorable ones may disappear.

Environmental Change: a change in the environment can affect an organism’s ability to survive and
therefore lead to natural selection
Evidence of Evolution: Fossils, patterns of early development, similar body structures, & similarities in
DNA and protein structures all provide evidence that organisms have changed over time.

Homologous structures: structures that related species have inherited from a common ancestor (i.e. bird’s
wing, dolphin’s flipper, & dog’s leg)
A new species can form when a group of individuals remains isolated from the rest of its species long
enough to evolve different traits that prevent reproduction.


Gradualism: small changes that add up to major changes over a long period of time
Punctuated Equilibrium: species evolve during short periods of rapid change, and then don’t change much