Unit 4 Outcome 2 Biology key terms

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AOS 2: Change Over Time

Adaptations: a feature of an organism that helps it to survive- that is, live long enough to produce viable offspring. Includes structure, behaviour, physiological mechanisms and biochemical reactions

Adaptive radiation: the process where organisms that have a recent common ancestor develop different adaptations in response to different environmental selection pressures

Allele frequency: the relative number of an allele in a population

Allopatric speciation: the process of formation of one or more new species from an existing population by geographical separation

Analogous structures: features of organisms that have similar functions but different basic structure

Artificial selection: the selection by humans/breeders of animal pr plants with desirable phenotypes and genotypes for selective breeding to produce individuals with specific characteristics

Biogeography: the study of the distribution of species

Biological evolution: a change in the inherited traits of a population of species over successive generations

Carbon dating: the analysis used to determine the relative age of organic material based on the content of 14C

Cenozoic: the 4th geological era from about 65 millions years before today

Cline: a gradual change in a characteristic or feature across the geographical range of a species or population

Cloning: making an exact replica of a gene or genetically identical cells/organisms arisen from a parent

Coevolution: the evolution of two species in tandem so that the two depend on each other

Comparative anatomy: the study of the similarities and differences between the anatomy of different species

Comparative embryology: comparison of the development of embryos of two or more species

Convergent evolution: the process whereby organisms that do not have recent common ancestors develop similar adaptations because they live in similar habitats (ie. similar selection pressures)

Cultural evolution: The continuous developmental process of a culture from simple to complex forms and from homogeneous to heterogeneous qualities.

Divergent evolution: the process whereby organisms that have different adaptations from their recent ancestors survive in changed habitats; or, the process whereby organisms with a recent common ancestor develop different adaptations in different habitats

DNA hybridisation: the process of pairing of complementary DNA chains or parts of chains

Evolution: the process of gradual change in a population of organisms that gives rise to a new species

Extinction: the process of death of all members of a population or species

Fitness: the measure of biological success of an organism in terms of the number of viable offspring it produces

Fossil: the preserved remains or traces of an organism

Fossil record: the collection of fossils of all sorts that provides the record of extinct life

Founder effect: the effect of genetic drift that occurs when a few individuals carrying a small proportion of the original gene pool are isolated from a population and interbreed

Gene flow: transfer of genes between populations

Gene pool: the collection of genes and their alleles present in a population of organisms

Gene therapy: a genetic engineering procedure designed to correct a genetic disorder

Genetic bottleneck: the change in the gene pool of a species brought about by the breeding of individuals carrying a small proportion of the alleles of the parent population

Genetic drift: the change in allele frequencies in a population due to chance: the action of the founder effect or the bottleneck effect

Genetic fitness: the ability of a particular trait being more able to survive

Genetic screening: examining DNA molecules to test for genetic disorders

Geological time: the geological time scale used to measure the time the earth has developed; divided into eons, eras, periods and epochs

Germ line gene therapy: the altering of gametes in order to affect their function in any offspring in any potential offspring

Germ cell: cells that give rise to gametes

Gondwana: southern precursor continent

Half-life: time required for an element to decay by a half- eg. Carbon, potassium, argon etc.

Hardy-Weinburg equilibrium: 5 principles that a population is required to have if equilibrium is to be met; very rare if not impossible in real life:

1. Small population

2. Random mating: every individual has an equal chance of mating

3. No migration

4. No selection pressure

5. No mutation

Heterozygous advantage: the case in which the heterozygous genotype has a higher relative fitness than the homozygous dominant or recessive genotype

Hominid: member of family Hominidae, eg. Man and distant relatives

Homo-: same

Homo sapiens: human

Homologous structures: features of organisms that have the same basic structure but may have different function

Inbreeding: mating of two closely related species

Inheritance of acquired traits: the theory that traits acquired by an organism during their lifetime to adapt to the environment can be passed down to offspring, originating from Lamarck

Isolation: (geographical, etc)

Jean-Baptiste Lamarck: see inheritance of acquired traits.


Macroevolution: evolution on a large scale over geological time and resulting in new taxonomic groups (new species)

Mesozoic era: the 3rd geological era from about 245 million years ago to about 65 million years ago

Microevolution: small changes in a population’s gene pool that lead to the accumulation of new characteristics, but don’t lead to the formation of a new species

Mitochondrial DNA: the circular molecules of DNA that are found in mitochondria and are less than 100 kilobases in length- from the maternal line

Molecular clock: a process that looks at differences between certain proteins of different species to determine the time at which the two species diverged from a common ancestor

Monoculture: the large-scale cultivation of a single species of plant in one area

Natural selection: a natural process that occurs in ecosystems where, at a particular time, certain members of a species that are more suited to the prevailing conditions within that given area are more likely to reproduce and pass on their alleles to the next generation

Neanderthal man: extinct robust human of Middle Palaeolithic in Europe and western Asia, said to be ancestors of Homo sapiens

Neo-Darwinism: the theory of evolution based on Darwin’s original theory of evolution of species through the process of natural selection together with current understandings and theories of genetics and inheritance

Out of Africa hypothesis: every living human being is a descendent of a small group from Africa

Paleozoic: the 2nd geological era from about 570 to 245 million years ago

Parapatric speciation: a type of speciation where populations that are initially isolated from each other partially diverge genetically, are then geographically reunited and are unable to interbreed because they have developed different reproductive behaviours

Parallel evolution hypothesis: development of similar trait in different but not closely related species who share a common ancestor

Phylogeny: evolutionary relationships that exist between species

Pluripotent: having more than one potential outcome

Polyploidy: the possession of one or more complete extra sets of chromosomes in each cell

Primate: an organism that has flattened nails, bicuspid teeth, a flattened face with a short nose and forward facing eyes, a tendency to upright locomotion and a well developed brain, known for thorough parental care of offspring

Radioactive isotope: an unstable element that occurs in varying forms, often used to determine age of rocks and fossils

Relative age: the age of something as compared to the age of another thing (ie geological units)

Reproductive isolation: a factor that prohibits interbreeding between individuals of two different species

Selection agents: a factor, usually environmental, that reduces the fitness of a particular phenotype in a population of organisms

Selection pressure: an environmental force altering the frequency of alleles in a population

Selective advantage: the phenotype that confers a survival advantage on an organism over another of the same species

Selective breeding: the process of breeding two particular organisms together to achieve a desired trait/ to influence the traits inherited by the next generation

Speciation: the formation of a new species

Species: a group of organisms that are recognized by morphology and can interbreed, being reproductively isolated from other species

Stem cell differentiation: the process by which these general cells become specific cells

Survival advantage: any characteristic that enables and individual to reproduce more effectively than its competitors- refers to both micro- and macro- evolution

Technological evolution: the advancement of using tools to aid survival

Transformation: a process that mainly occurs in bacteria, in which DNA from another organism is accepted into the genome of the host

Transgenic organisms: having one or more genes in its genome that have come from another organism

Variation: differences in various traits that exist between members of a population

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