Apex Biology Unit 7
Early Earth
Terms
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- adaptive radiation
- Repeated speciation events originating from one or few species
- topography
- The surface features of an area, such as mountains, rivers and valleys.
- protoplanets
- Regions of condensed matter that serve as a starting point for the formation of a planet.
- substitution mutation
- Mutation in which a single base is replaced, potentially altering the gene product.
- index fossils
- Fossils that are characteristic of sedimentary rock from a particular span of geologic time.
- bottleneck
- A stressful period in which few organisms of a population survive, resulting in loss of genetic variation in the population.
- polyploidy
- Condition in which an organism or cell has more than two complete sets of chromosomes.
- mold
- the space left in a rock by an organism or its parts that have decayed
- chemical evolution
- The evolution of the first single-celled life forms from simple inorganic molecules
- 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.
- radiocarbon dating
- Form of radioactive dating that measures the amount of radioactive carbon in an object.
- isolating mechanisms
- Any environmental, behavioral, mechanical or anatomical barriers that prevent members of different populations from producing viable offspring.
- speciation
- The evolutionary process of the formation of new species.
- diversification
- One or multiple adaptive radiation events resulting in multiple species.
- 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.
- homologous structures
- Anatomical structures that may look different or perform different functions but that share a common ancestor.
- ecological niche
- A specific role of a species within an ecosystem, including its use of resources, and relationships with other species.
- 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
- 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
- galaxy
- A system composed of a large number of stars, gas and dust orbiting a common center of gravity.
- 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.
- regulatory sequences
- Non-coding portions of DNA that provide marker regions to start DNA expression.
- induced mutations
- Mutations that originate external to the cell, possibly caused artificially by radiation or chemicals, usually for experimental purposes
- permineralization
- The process by which minerals replace parts of an organism.
- organic
- In chemistry, any chemical compound containing carbon.
- germ line mutation
- An inherited mutation passed on down to subsequent generations
- spontaneous mutations
- Mutations that originate within the cell due to the failure of cellular replication or of the DNA's repair mechanisms.
- paleontologist
- Scientist who studies the forms of life existing in prehistoric times, as represented by the fossils of plants, animals, and other organisms.
- universe
- All matter and energy, including the earth and the galaxies
- enzymes
- Proteins specialized for catalyzing (speeding up) chemical reactions, including DNA expression.
- population genetics
- The study of how collections of genes are passed from generation to generation and the variation of such genes
- fossil record
- The orderly collection of fossils found from all different periods of time.
- gene flow
- The exchange of genes between species or between different populations of the same species.
- periods
- Subdivisions of an era in geologic time.
- specialization
- When different cells in an organism express certain genes more or less to give the cells different functions.
- analogous structures
- Anatomical structures that may look similar or perform similar functions but that have different evolutionary origins.
- phenotype
- The outward appearance of a particular trait.
- genotype
- A specific combination of alleles for a certain gene.
- geologic timetable
- Timeline of ages and events that highlights the appearance (and disappearance) of different groups of organisms over time.
- radioactive isotope
- A form of a chemical element that is unstable and decomposes to a different element while giving off energy and radioactive particles.
- polygenic trait
- A feature or characteristic resulting from the expression of many genes, such as height or body weight.
- founder effect
- Genetic effects resulting from bottleneck caused when one or a few individuals begins a new population.
- epochs
- Subdivisions of a period in geologic time.
- 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.
- petrification
- The process by which organic material is turned into stone.
- imprint
- Impression left in soft material, important in the study of fossils.
- hybrid zone
- Area where two populations' ranges overlap resulting in offspring that are a mix of the two populations' gene pools.
- genetic drift
- Changes in allele frequencies from generation to generation that result from random processes.
- isotopes
- Forms of elements that have different numbers of neutrons in their nucleus.
- planets
- celestial bodies moving in an elliptical orbit round a star
- cast
- A three-dimensional copy of the outside of an organism.
- 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.
- variation
- A difference between two members of the same species.
- adaptation
- A physical or behavioral change that improves a population's survival in a given environment.
- 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).
- artificial selection
- Changes that occur in a species over time due to selective breeding or preference by humans.
- our solar system
- The sun together with the nine planets and all other celestial bodies that orbit the sun.
- chromosomal mutation
- Change in a DNA sequence that affect an entire chromosome or multiple chromosomes.
- 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.
- 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.
- gene pool
- The sum of genetic information for an interbreeding population (species).
- allele frequency
- The relative proportion of a specific allele within a population
- frameshift mutations
- Types of mutations that result from insertion or deletion of a single nucleotide into the normal DNA sequence.
- somatic mutation
- Mutation arising in body cells that is not genetically transmitted to offspring; some may result in cancer.
- vestigial structure
- A type of homologous structure that remains in an organism through evolution, but which no longer serves any biological function.
- 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.
- 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).
- 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
- eras
- Largest divisions of geologic time.
- half life
- The time for half the atoms in a radioactive substance to disintegrate
- geology
- The structure and composition of a certain region on the Earth's crust.
- fossil
- Preserved evidence of an organism; often consisting of bones, teeth or other body parts but sometimes including impressions of the organism.