PCBl 3044l Examl 2l Latestl 2026l 2027l

PCBl 3044l Examl 2l (Latestl 2026/l 2027l Update)l Review|l 100%l Verifiedl Questionsl &l Answersl |l Gradel A

Q:l Whatl isl geneticl drift?l Isl geneticl driftl anl examplel ofl naturall selection?l Whatl typesl ofl populationsl arel morel impactedl byl geneticl drift?

Answer:

-Geneticl driftl isl whenl randoml eventsl affectl whichl allelesl arel passedl froml onel generationl tol thel next.l Itl isl greaterl inl smallerl populationsl thanl inl largel ones.

-Geneticl driftl isl notl anl examplel ofl naturall selection,l itl happensl throughl anl entirelyl randoml process.

-Smalll populationsl arel morel impactedl byl geneticl drift.

Q:l Whatl fourl possiblel effectsl canl geneticl driftl havel onl al population?

a.l Whatl isl fixation?l Howl doesl thisl affectl thel geneticl variationl ofl al population?

b.l Whyl canl onlyl mildlyl deleteriousl effectsl increasel vial geneticl driftl andl notl terriblyl deleteriousl ones?l (Hint:l Whatl effectl mightl al terriblyl deleteriousl allelel havel anl organism'sl abilityl tol reproduce?l Arel allelel frequenciesl stilll basedl onl randoml chancel inl thisl case?)l

c.l Howl canl geneticl driftl increasel geneticl differencesl betweenl populations?

Answer:

-Fourl possiblel effectsl ofl geneticl driftl onl al population:

l 1.l Canl causel allelel frequenciesl tol fluctuatel randomlyl overl timel inl smalll populations.l Eventually,l somel allelesl disappearl froml smalll populations,l whilel othersl reachl fixation.

l 2.l Geneticl driftl reducesl thel population'sl geneticl variation,l makingl thel individualsl withinl thel populationl morel similarl geneticallyl tol onel another.

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l 3.l Geneticl driftl canl increasel thel frequencyl ofl al harmfull allele.

l 4.l Geneticl driftl canl increasel geneticl differencesl betweenl populationsl becausel randoml eventsl mayl causel anl allelel tol reachl fixationl inl onel populationl yetl bel lostl froml anotherl population.l

-Fixationl isl whenl anl allelel occursl inl al populationl atl al frequencyl ofl 100%.l Fixationl causesl lowl geneticl variationl inl al population.

-Geneticl driftl canl "overrule"l thel effectsl ofl naturall selection,l causingl al harmfull allelel tol randomlyl increasel orl decreasel inl frequency.

-l Geneticl driftl canl increasel geneticl differencesl betweenl populationsl becausel randoml eventsl mayl causel anl allelel tol reachl fixationl inl onel populationl yetl bel lostl froml anotherl population.

Q:l Whichl twol effectsl ofl geneticl driftl arel mostl detrimentall tol al population?l Why?

Answer:

-Thel secondl andl thirdl effectsl canl havel direl consequencesl forl smalll populations.l Thisl isl becausel al lossl ofl geneticl variationl canl reducel thel capacityl ofl al populationl tol evolvel inl responsel tol changingl environmentall conditions,l potentiallyl placingl itl atl riskl ofl extinction.l Likewise,l anl increasel inl thel frequencyl ofl harmfull allelesl inl al populationl canl hinderl thel abilityl ofl itsl membersl tol survivel orl reproduce,l againl increasingl thel riskl ofl extinction.

Q:l Whatl isl genel flow?l Whatl effectsl canl genel flowl havel onl al population?

Answer:

-Genel flowl occursl whenl allelesl arel transferredl froml onel populationl tol anotherl vial thel movementl ofl individualsl orl gametes.l (e.g.,l plantl pollen).

-Genel flowl hasl twol importantl effects.l First,l byl transferringl allelesl betweenl populations,l itl tendsl tol makel populationsl morel similarl tol onel anotherl genetically.l Second,l genel flowl canl introducel newl allelesl intol al population.

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Q:l Whatl isl adaption?l Whatl featuresl ofl anl organisml canl bel adaptedl tol thel environment?

Answer:

-Adaptationsl arel featuresl thatl evolvel byl naturall selectionl andl improvel anl organism'sl abilityl tol survivel andl reproducel inl itsl environment.

-Thel featuresl ofl anl organisml thatl canl bel adaptedl tol thel environmentl arel theirl structure,l physiology,l andl behavior.

Q:l Whyl isl naturall selectionl consideredl tol bel adaptivel evolution?l Arel traitsl withl anl overalll negativel impactl selectedl forl byl naturall selection?l Whatl arel somel examplesl ofl adaptivel evolution?

Answer:

-Naturall selectionl isl consideredl adaptivel evolutionl becausel itl isl al processl ofl changel inl whichl traitsl thatl conferl survivall orl reproductivel advantagesl tendl tol increasel inl frequencyl overl time.

-Traitsl withl anl overalll negativel impactl arel notl selectedl byl naturall selection.l Whenl naturall selectionl operates,l individualsl withl certainl allelesl predictablyl havel higherl survivall andl producel morel offspringl thanl individualsl withl otherl alleles.

-Naturall selectionl inl soapberryl bugl populationsl causedl adaptivel evolutionl inl whichl al characteristicsl ofl thel organisml (beakl length)l evolvedl tol matchl anl aspectl ofl itsl environmentl (fruitl size)l morel closely.

Q:l Whatl arel clines?

Answer:

-Clinesl arel patternsl ofl changel inl al characteristicl ofl anl organisml overl al geographicall region.

Q:l Howl havel organismsl respondedl tol climatel change?

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Answer:

-Organismsl havel alteredl theirl timingl ofl keyl eventsl inl theirl lives,l suchl asl delayingl thel onsetl ofl winterl dormancyl orl reproducingl earlierl inl thel spring.

Q:l Whatl isl phenotypicl plasticity?

Answer:

-Phenotypicl plasticityl isl thel abilityl ofl onel genotypel tol producel morel thanl onel phenotypel inl differentl environments.

Q:l Howl canl genel flowl limitl adaption?l Whatl doesl itl meanl tol sayl thatl adaptivel evolutionl canl onlyl occurl ifl naturall selectionl forcesl arel strongl enoughl tol overcomel genel flow?

Answer:

-Thel extentl tol whichl adaptivel evolutionl occursl inl eachl populationl dependsl onl whetherl naturall selectionl isl strongl enoughl tol overcomel thel effectsl ofl ongoingl genel flow.

-Naturall selectionl andl adaptivel evolutionl arel drivenl byl ecologicall interactions-l organismsl interactingl withl onel anotherl andl theirl environment

Q:l Isl naturall selectionl perfect?l Explain.

Answer:

-Naturall selectionl isl notl perfect,l thisl occursl becausel anl organism'sl environmentl isl notl static-itl isl al movingl targetl becausel thel abioticl andl bioticl componentsl ofl thel environmentl changel continually.

Q:l Whatl threel factorsl canl limitl evolution?

l a.l Canl adaptivel evolutionl occurl atl al genel ifl nol allelel isl morel beneficiall thanl anotherl orl ifl therel isl onlyl onel availablel allele?l

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