【ThePepperedMothakindofinsectisfoundinEngland.Itislightbrownincolorandlikestosettleontreeswhicharealsolightbrown.Thismakesthemothdifficulttobeseenandbirdsarelesslikelytonoticeandeatit.】
ThePepperedMothakindofinsectisfoundinEngland.Itislightbrownincolorandlikestosettleontreeswhicharealsolightbrown.Thismakesthemothdifficulttobeseenandbirdsarelesslikelytonoticeandeatit.
Butwiththedevelopmentofindustrysmokefromfactoriesbegantoreachthetreeswherethemothsettled.Itmadethetreesblacker.Thensomethingverystrangetookplace:inindustrialareasthePepperedMothbegantochangecolor.Itbecamedarkeraswell.Althoughthechangetookseveralyearssomescientistssoonnoticedthatnewly-bornmothswerealittledarkerthanusual.
AscientistcalledKettleWelldecidedtomakeacarefulstudyofthis.HemarkedsomeofthelightmothsandsomeofthedarkeronesandsetthemfreeinthewoodsnearBirminghamanindustrialcity.Laterheretargetasmanythemarkedmothsaspossible(Theresultwasgiveninthechart).
KettleWell’sresearchwasdoneintheearly1950s.SoonafterwardsBritainintroducednewlawstoreducesmokeandfactorypollution.
CanyouimaginewhatwouldhappentothePepperedMothastheairbecamecleaneragain?
lightmoths
darkermoths
Mothssetfree
201
601
Mothsrecaught
34(16%)
206(34%)
1.ThetreeswherethePepperedMothsettledchangedtheircolorbecause_____________________________.
A.thePepperedMothchangeditscolor
B.thePepperedMothcouldn’tbeeasilyfoundonthem
C.industryinEnglanddevelopedquickly
D.thesmokefromfactoriespollutedthem
2.ThePepperedMothbegantochangeitscolorinindustrialareasbecause _____________________________.
A.itchangeditscolorallthetime
B.itwasfondofthecolorofitslivingplace
C.ithadtoprotectitselfbydoingso
D.itwasaspecialsortofinsect
3.FromtheresultsofKettleWell’sresearchwecanseethat_________________.
A.manymoreofthelightmothswerekilledoreaten
B.morethanone-fifthofthelightmothsescapedbeingkilled
C.threetimesasmanydarkmothswerekeptsafeaslightone