evolution and ecology review

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  • 7/24/2019 Evolution and Ecology Review


    Topic D.1: Origin of Life on Earth

    D.1.1 Describe the four processes needed for the spontaneous origin of life on Earth.

    1) Non-living synthesis of simple organic molecules

    a) Early Earth provided elements + chemicals needed for lifeb) Oceans mixture of inorganic molecules simple organic molecules

    c) Organic chemicals from Earth or space

    !) "ssembly of these molecules into polymersa) #olymeri$ation formation of larger% more complex organic chemicals in oceans

    &) Origin of self-replicating molecules made inheritance possible

    a) DN" re'uires protein en$ymes for replicationb) (N" capable of self-replication

    i) ataly$e its formation from nucleotides *o proteins

    ii) (N"-based catalyst ,ribo$yme)

    c) apable of undergoing evolution by natural selection) #acaging of these molecules into membranes * internal chemistry different from surroundings

    a) losed membrane vesicles form spontaneously from lipids

    b) Different internalexternal environments cellular metabolism

    D.1.2 Outline the experiments of /iller and 0rey into the origin of organic compounds.

    1) Earths Developmenta) 2ormed .3 billion years ago from cloud of dust particles around 4un

    b) 5eat from force of gravity + radioactive decay melted interior dense metallic core ,iron + nicel)

    i) 4urrounded by cool li'uid mantlec) During cooling of crusts% gases from hot interior escaped through volcanoes atmosphere of

    hydrogen% *ater vapor% methane% ammonia% nitrogen and hydrogen sulfide

    d) 6aced of oxygen reducing atmosphere

    e) /onomers of biological molecules formed in shallo* ocean *aters as products of reactions btsimple organic compounds in atmosphere + *ater

    i) #rimeval soup or chemical soup!) /iller and 0reys Experimentsa) 4imulated early Earth conditions

    b) Establish if chemical evolution could occur in primeval soup

    c) 7ater ,5!O)% methane ,5)% ammonia ,N5)% hydrogen ,5!)d) 4ealed in sterile glass tubes + flass connected in loop

    i) 2lass one *ater% one * pair of electrodes

    e) 7ater heated to produce steam% spars produced bt electrodes ,lightning)

    f) /ixture cooled*ater condensed + tricled bac into first flas continuous cycle

    g) "fter 1 *ee% 138 of carbon organic compounds

    i) 1& of !9 natural amino acids

    ii) 5igh concentration of adenine

    D.1.3 4tate that comets may have delivered organic compounds to Earth.

    1) #anspermia

    a) 5ypothesis that life on Earth may have originated by introduction of complex organicchemicalsbacteria via comets

    b) omet small body in solar system orbiting 4un

    c) 4ome bacteria + archaebacteria resistant to extreme conditions% possibly in deep spacei) 4emi-dormant bacteria deep in "ntarctic ice cores

    d) osmic radiation energy for organic molecule synthesis

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    i) omet spectra hydrocarbons% amino acids% peptides

    D.1.4 Discuss the possible locations *here conditions *ould have allo*ed the synthesis of organiccompounds.

    1) "biogenesis

    a) :eneration of life from chemicalsb) 5ydrothermal ;ents


    iv) /artian meteorites ,possibly * fossili$ed bacteria) found in "ntarctica

    D.1.5 Outline t*o properties of (N" that *ould have allo*ed it to play a role in the origin of life.

    1) (N" 7orld 5ypothesisa)

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    c) "ccumulation organisms *hich synthesi$ed protective en$ymes ,e.g. catalase)


  • 7/24/2019 Evolution and Ecology Review


    iii) 4ome hybrids cannot mate * o*n ind but possibly * parent species

    iv) ?n ring species% members of ad@acent populations interbreed successfully ,not if *idely separated)v) an be physically impossible for members of same species to mate

    vi) ?ndividuals forming single gene pool

    f) Evolutionaryi) :roup of organisms sharing uni'ue collection of structural + functional characteristics

    g) ladistic

    i) :roup of organisms sharing common ancestorii) /embers may diverge separate species

    D.2.4 Describe three examples of barriers bet*een gene pools.

    1) :enetic ?solationa) ommonest re'uirement for speciation

    b) "ccumulation of different allele fre'uencies

    c) /aintained by reproductive isolating mechanismsd) #re$ygotic ?solation

    i) Bygotes not formed bc gametes dont meet + fertili$e

    ii) =emporal ?solation /ateflo*er at different timesiii) Ecological ?solation occupy different same region but different habitats


  • 7/24/2019 Evolution and Ecology Review


    D.2.6 ompare allopatric and sympatric speciation.

    1) 4peciationa) #rocess by *hich one or more species arise from previously existing species

    b) One species ne* species intraspecific speciation

    i) ?f occurs *hile populations are physically separated allopatric speciation,1) :eographical barrier blocs gene flo* adaptations to ne* environment changes in allele +

    gene fre'uencies reproductive isolation

    ii) ?f occurs *hile populations are occupying same area sympatric speciationc) ! speciesne* species interspecific speciation

    D.2.7 Outline the process of adaptive radiation.

    1) "daptive (adiationa) :roup of organisms share homologous structures *hich are differentiated to perform variety of


    b) Occurs in all taxonomic group except speciesc) 4hared features adaptations to particular environments

    D.2.8 ompare convergent and divergent evolution.

    1) onvergent Evolutiona) Distantly related organisms evolve similar traits as they adapt to similar environments or ecological


    b) (esult in analogous structuresc) 4imilarity due to pressure from natural selection

    !) Divergent Evolution

    a) =*o or more adaptations have common evolutionary origin but have diverged over time ,adaptiveevolution)

    b) (esult in homologous structures

    c) 4imilarity due to common origin&) #arallel Evolution

    a) =*o species maintain same degree of similarity *hile each undergoes evolutionary changeindependently

    D.2. Discuss ideas on the pace of evolution including gradualism and punctuated e'uilibrium.

    1) #unctuated E'uilibrium

    a) /any species sho* stasis throughout much of geological historyb) "ccount for observed gaps in fossil record

    c) (apid evolutionary change occurs during speciation

    d) Occurred in small portion of population at edge of geographical range ,higher selective pressure inperipheral populations) peripatric speciation

    !) #hyletic :radualism

    a) /ost evolutionary change relatively slo* but not uniform rateb) One species gradually transforms into another

    &) 4tabili$ing 4election

    a) Operates *hen environmental conditions favorable to particular phenotype + competition isntsevere

    b) Eliminates extreme phenotypes maintains phenotypic stability% doesnt promote evolutionary


    ) Directional 4electiona) (esponse to gradual environmental changes

    b) #ressure to move mean to*ard ne* mean

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    c) 6eads to stabili$ing selection

    3) Disruptive 4electiona) 2luctuating conditions favor presence of ! phenotypes

    b) /ay split into ! sub-populations + later speciation

    D.2.1! Describe one example of transient polymorphism.1) #olymorphism

    a) Existence of ! or more forms of same species *in population

    b) =ransient #olymorphismi) One allele displacing anotherii) ExC ?ndustrial /elanism in

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    1) #rimates

    a) 5umans% lemurs% moneys% gibbons% apes ,orangutans% gorillas% chimpan$ees)b) "pes + humans distinguished by being tailless + free motion of arms over head

    c) :rasping limbs opposable thumb grip for po*er + precision

    d) (otating forelimb hand can rotate through 1G9H

    e) 4tereoscopic vision eyes close together on face * parallel optical axes

    f) ;isual activity increased numbers of rodscones * o*n nerve cells

    g) (educed olfaction reduced snout allo*ing flatter faceh) Enlarged sullexpanded area for cerebrum% ventral foramen magnum

    i) 6arge brain increased sensorymotor areas% deeply fissured

    @) 2e* offspring longer gestation

    ) 4ocial dependencycorporate activities% group cohesion

    l) "dapted to arboreal ,tree-d*elling) life pre-adapted ,fortuitous) human ancestors to ne* niches

    *hen "frican forests gave *ay to drier grassland savannas 3 mya

    D.3.5 Outline the trends illustrated by the fossils ofArdipithecus ramidus%Australopithecus includingA.

    afarensisandA. africanus% andHomoincludingH. habilis%H. erectus%H. neanderthalensisandH.sapiens.

    1) 4ulls and

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    f) 6ong life span

    ) 5ominid Evolution

    'en#s of


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