| Term | Definition |
|---|
| universe | All matter and energy, including the earth and the galaxies |
| galaxy | A system composed of a large number of stars, gas and dust orbiting a common center of gravity. |
| our solar system | The sun together with the nine planets and all other celestial bodies that orbit the sun. |
| planets | celestial bodies moving in an elliptical orbit round a star |
| protoplanets | Regions of condensed matter that serve as a starting point for the formation of a planet. |
| protoplanet hypothesis | A widely accepted explanation for the formation of Earth and the solar system from the condensation of dust and other matter in the gases surrounding the sun. |
| organic | In chemistry, any chemical compound containing carbon. |
| chemical evolution | The evolution of the first single-celled life forms from simple inorganic molecules |
| endosymbiosis | Process through which early prokaryotic cells are thought to have engulfed other, smaller cells and eventually incorporated them as organelles; these cells evolved into modern-day eukaryotes. |
| specialization | When different cells in an organism express certain genes more or less to give the cells different functions. |
| fossil | Preserved evidence of an organism; often consisting of bones, teeth or other body parts but sometimes including impressions of the organism. |
| petrification | The process by which organic material is turned into stone. |
| permineralization | The process by which minerals replace parts of an organism. |
| mold | the space left in a rock by an organism or its parts that have decayed |
| cast | A three-dimensional copy of the outside of an organism. |
| imprint | Impression left in soft material, important in the study of fossils. |
| paleontologist | Scientist who studies the forms of life existing in prehistoric times, as represented by the fossils of plants, animals, and other organisms. |
| geologic timetable | Timeline of ages and events that highlights the appearance (and disappearance) of different groups of organisms over time. |
| eras | Largest divisions of geologic time. |
| periods | Subdivisions of an era in geologic time. |
| epochs | Subdivisions of a period in geologic time. |
| index fossils | Fossils that are characteristic of sedimentary rock from a particular span of geologic time. |
| isotopes | Forms of elements that have different numbers of neutrons in their nucleus. |
| half life | The time for half the atoms in a radioactive substance to disintegrate |
| topography | The surface features of an area, such as mountains, rivers and valleys. |
| geology | The structure and composition of a certain region on the Earth's crust. |
| descent with modification | The idea that organisms can pass down traits such that one generation will be slightly different than the previous generation; over time, the more beneficial traits tend to survive. |
| adaptation | A physical or behavioral change that improves a population's survival in a given environment. |
| natural selection | The theory that only the organisms with the most suited genotype in their preferred living area will be able to survive when abiotic stress is applied on the species |
| variation | A difference between two members of the same species. |
| evolution | The gradual process by which small changes that occur due to natural selection accumulate to change an organism to a new and more adapted form |
| radioactive dating | The method of determining the age of an object by comparing the amount of radioactive substance (which breaks down at a certain rate) in the object to the amount of the same radioactive substance in similar objects present on Earth today. |
| radioactive isotope | A form of a chemical element that is unstable and decomposes to a different element while giving off energy and radioactive particles. |
| radiocarbon dating | Form of radioactive dating that measures the amount of radioactive carbon in an object. |
| artificial selection | Changes that occur in a species over time due to selective breeding or preference by humans. |
| fossil record | The orderly collection of fossils found from all different periods of time. |
| gradualism | The theory that Earth's topography and geology were formed by the accumulation of a large number of small events caused by everyday natural processes. |
| homologous structures | Anatomical structures that may look different or perform different functions but that share a common ancestor. |
| vestigial structure | A type of homologous structure that remains in an organism through evolution, but which no longer serves any biological function. |
| analogous structures | Anatomical structures that may look similar or perform similar functions but that have different evolutionary origins. |
| population genetics | The study of how collections of genes are passed from generation to generation and the variation of such genes |
| gene pool | The sum of genetic information for an interbreeding population (species). |
| induced mutations | Mutations that originate external to the cell, possibly caused artificially by radiation or chemicals, usually for experimental purposes |
| spontaneous mutations | Mutations that originate within the cell due to the failure of cellular replication or of the DNA's repair mechanisms. |
| germ line mutation | An inherited mutation passed on down to subsequent generations |
| somatic mutation | Mutation arising in body cells that is not genetically transmitted to offspring; some may result in cancer. |
| chromosomal mutation | Change in a DNA sequence that affect an entire chromosome or multiple chromosomes. |
| substitution mutation | Mutation in which a single base is replaced, potentially altering the gene product. |
| frameshift mutations | Types of mutations that result from insertion or deletion of a single nucleotide into the normal DNA sequence. |
| regulatory sequences | Non-coding portions of DNA that provide marker regions to start DNA expression. |
| enzymes | Proteins specialized for catalyzing (speeding up) chemical reactions, including DNA expression. |
| allele frequency | The relative proportion of a specific allele within a population |
| polygenic trait | A feature or characteristic resulting from the expression of many genes, such as height or body weight. |
| directional selection | Natural selection that acts against one type of extreme form of a polygenic trait to reduce genetic variation and change the average value of a trait within a population. |
| stabilizing selection | Natural selection that acts against extreme forms of a polygenic trait to reduce genetic variation while not changing the average value of a trait within a population. |
| disruptive selection | Natural selection that acts against intermediate forms of a polygenic trait to increase genetic variation while not changing the average value of a trait within a population |
| genetic drift | Changes in allele frequencies from generation to generation that result from random processes. |
| bottleneck | A stressful period in which few organisms of a population survive, resulting in loss of genetic variation in the population. |
| gene flow | The exchange of genes between species or between different populations of the same species. |
| species | A group of interbreeding natural populations that are reproductively isolated from other such groups; the most specific taxonomic level. |
| reproductive isolation | Condition in which a population is unable to breed with other populations of the same species. |
| speciation | The evolutionary process of the formation of new species. |
| isolating mechanisms | Any environmental, behavioral, mechanical or anatomical barriers that prevent members of different populations from producing viable offspring. |
| pre-zygotic isolating mechanism | Non-biological or biological process that prevents interbreeding between populations prior to fertilization (for example, different mating behaviors or incompatible sexual organs). |
| post-zygotic isolating mechanism | A biological process that prevents successful production of offspring after fertilization (for example, failure of the embryo to develop or infertility of offspring). |
| polyploidy | Condition in which an organism or cell has more than two complete sets of chromosomes. |
| genotype | A specific combination of alleles for a certain gene. |
| phenotype | The outward appearance of a particular trait. |
| founder effect | Genetic effects resulting from bottleneck caused when one or a few individuals begins a new population. |
| hybrid zone | Area where two populations' ranges overlap resulting in offspring that are a mix of the two populations' gene pools. |
| adaptive radiation | Repeated speciation events originating from one or few species |
| diversification | One or multiple adaptive radiation events resulting in multiple species. |
| ecological niche | A specific role of a species within an ecosystem, including its use of resources, and relationships with other species. |
Combine with other sets
Share on Facebook
Share on MySpace