Biology - Unit 7 Test

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evolution

evolution

change in genes of a species over time

process by which modern organisms have descended from ancient organisms

Linnaeus

classification system for organisms grouped by similarities: reflects evolutionary relationships

rejected that organisms don’t change over time

Buffon

species share ancestors rather than separately

suggested Earth older: most believed 6000 years old

Erasmus Darwin

living things descended from common ancestor

more-complex forms developed from less-complex

Lamarck

environment change cause behavior change, led to use or disuse of structure, these changes passed on

idea: the inheritance of acquired characteristics - wrong

Cuvier

species could become extinct

fossils in deep layers of rock different from fossils in upper

proposed catastrophism

catastrophism

natural disasters shape landforms & cause mass extinctions

Hutton

gradualism

earth older than believed

gradualism

changes in landforms due to slow changes over long period

Lyell

Principles of Geology

theory of uniformitarianism

influenced Darwin

uniformitarianism

prevailing geologic change theory: geological processes are constant and ongoing

Wallace

1858: writes to Darwin about natural selection

1859: Darwin “The Origin of the Species” acknowledges him

natural selection principles

variation, overproduction, adaptation, descent w modification

differential survival

some in population have phenotypic advantage

selective pressure

changing environment favor some phenotypes over others

radiometric dating

estimate age of fossils use decay of unstable isotopes

half-life

amount of time it takes for half of the isotope to decay

relative dating

estimates time which organism lived: compares fossil placement in rock layers: scientists infer order species existed

index fossils

determine relative rock layer age: existed during specific time, large geographic areas: include fusulinids & trilobites

comparative biochemistry

2 closely-related organisms will have similar DNA sequence: molecular evidence

hox/homebox genes

control development of specific structures

found in many organisms

protein comparisons/molecular fingerprinting: similarities among cell types of different organisms

single gene traits

fewer phenotypes: limited, 2 alleles

change allele frequencies: evolution

polygenic trait

many genotypes/phenotypes, distribution curve

directional selection

moves frequency of an allele in one direction

stabilizing selection

2 opposing forces affect frequency of an allele

disruptive selection

population splits into two subgroups

5 factors to evolution

gene flow, mutation, sexual selection, genetic drift, natural selection

gene flow

join new populations/reproduce, keep neighboring populations similar, low gene flow: increases chance 2 populations evolve differently

genetic drift

loss genetic diversity/harmful alleles common, small pop

bottleneck: event drastically reduces population size

founder: colonize habitat: carry diff allele than larger pop

Hardy-Weinberg equilibrium

large pop, no migration, no mutation, random mating, no natural selection

reproductive isolation

diff pop can’t mate successfully, no gene flow, genetic differences add over generations, leads to speciation

speciation

rise of 2 or more species from 1 existing species

isolation types

behavioral: diff courtship/mating behaviors

geographic: physical barriers

temporal: diff timing of reproductive periods

convergent evolution

evolution toward similar traits in unrelated species

divergent evolution

evolution toward different traits in closely related species

coevolution

2 or more species evolve in response to changes in each other

beneficial/competitive relationships: evolutionary arms race

background extinction

continuous at low rate: same as speciation

affects few species in small area

caused by local changes in environment

mass extinction

rare, destroy many species: global level

caused by catastrophic events - 5 in last 600 million years

punctuated equilibrium

speciation episodes suddenly in geologic time, followed by long periods of little evolutionary change

revised Darwin’s idea: species arose: gradual transformations

adaptive radiation

many species evolve from 1

ancestral species diversifies into many descendants: adapted to wide range of environments

Cenozoic

65 mya – present: primate evolution, mammal diversification, flowering plants

Mesozoic

248-65 mya: evolution reptiles, “Age of the Reptiles”, ferns, mammals, ended with dinosaur extinction

Paleozoic

544-248 mya: all animal phyla develop: “Cambrian explosion”, early land plants develop, ended: mass extinction

early earth

began forming 4.6 bya: not suitable for life, very hot, little O2

cooled 3.8 bya: oceans formed

Miller-Urey experiment

simulation of early earth’s conditions

organic compounds made by passing electrical current to stimulate lightning, through closed system: held gas mixture

meteorite hypothesis

amino acids arrived on Earth through meteorite impact

iron-sulfide bubbles hypothesis

biomolecules formed in compartments on ocean floor

lipid membrane hypothesis

lipid spheres form around organic molecules: cell membrane

RNA

1st genetic material, ribozymes: self replicate

DNA: needs enzymes to replicate

cyanobacteria

oldest known fossils, prokaryotic cells, add O2 to \n atmosphere, deposited minerals

endosymbiosis

relationship: 1 organism lives within body of another mitochondria/chloroplasts: developed: forming eukaryotes

sexual reproduction evolution

increased diversity/variation: advantage, led evolution of multicellular life

multicellularity

more complex organisms: 100 million yrs after sexual reproduction began: evolution occur quickly.

organisms more fit: better competitors

pseudogenes

like vestigial structures: no longer function carried w/ DNA, change as passed through generations: figure evolutionary relationships, similarities: reflect common ancestor

protein comparisons

similarities among cell types revealed by comparing proteins: molecular finger-printing, unique set of proteins found types, computers search databases look for homologous sequences