NameDatePeriod
Worksheet:PunnettSquare Review
1.Inpeaplants,tall(T)plantsaredominantovershort(t)plants.Completethefollowingcrossesandgivethegenotypicandphenotypicratiosofoffspring.
a.TTxtt
b.Ttxtt
c.TtxTt
2.Inpeaplants,purpleflowers(P)aredominantoverwhite(p)flowers.Completethefollowingcrossesandgivethegenotypicandphenotypicratiosofoffspring.
a.Aheterozygouspurpleplantiscrossedwithahomozygouspurpleplant.
b.Acrossbetweentwopeaplantsproducesoffspringinwhichapproximately50%oftheflowersarewhiteand50%arepurple.Whatarethegenotypesoftheparents?Showpunnettsquaretosupportyouranswer.
c.Acrossbetweentwopurplepeaplantsyieldsapproximately25%oftheoffspringexhibitingwhiteflowers.Whatarethegenotypesoftheparents?Showpunnettsquaretosupportyouranswer.
3.Awidow’speakinhumansisdeterminedbyadominant/recessiveinheritance.Aperson whoispurebredforwidow’speakiscrossedwithapersonwhoispurebredfornowidow’speak.Alloftheoffspringhaveawidow’speak.Whichtraitisdominantandwhichisrecessive?Showpunnettsquaretosupportyouranswer.
4.Inguineapigs,blackfurisdominant.Ifablackguineapigiscrossedwithawhiteguineapigandthelittercontainsawhiteoffspring,thegenotypeoftheblack-hairedparentisprobably?Showpunnettsquaretosupportyouranswer.
5.Inminks,brownisdominantoversilver-bluecolor.
a.Whatoffspringwouldyoupredictifyoucrossedahomozygousbrownminkwithasilver-bluemink?Showpunnettsquaretosupportyouranswer.
b.WhatwouldthegenotypicandphenotypicratiosoftwoF2generationminkfromtheaboveproblembeiftheywerecrossed?Showpunnettsquaretosupportyouranswer.
6.Insnapdragons,redisnotcompletelydominantoverwhiteflowers.
a.Whatcolorflowerswouldyouexpectwhenyoucrossaredflowerwithawhiteflower?Whatwouldbethegenotypicandphenotypicratiosoftheoffspringbe?
b.CrosstwooftheF1generationfromabove.Whatwouldbethegenotypicandphenotypicratiosoftheoffspringbe?
7.Indragons,theabilitytobreathfireisarecessivetrait.Homozygousdominantdragonscannotproducefireorsmokeatall.Heterozygousdragonscanproducesmoke,butnofire.
a.Crossafirebreathingdragonwithahomozygousdominantdragon.Whatwouldbethegenotypicandphenotypicratiosoftheoffspringbe?
b.Crosstwosmoke-producingonlydragons.Areanyoftheoffspringabletoproducefire?Showpunnettsquaretosupportyouranswer.
8.Incattle,redandwhitehairarecodominant.Theheterozygousconditionisroancolored(containsbothredhairandwhitehair)
a.Crossaredcowandawhitecow.Whatwouldbethegenotypicandphenotypicratiosoftheoffspringbe?
b.Woulditbepossibletohaveanyredcattlewhentworoancattlearecrossed?Showpunnettsquaretosupportyouranswer.
9.InGuineapigs,thegenotype(BB)isblack,andthegenotype(bb)iswhitecolor,and(Bb)isgreycolor,Thegene(B)and(b)aresex-linked.
a.Whattypeofoffspringaretobeexpectedinacrossbetweenablackfemaleandawhitemale?
b.Aheterozygousfemaleiscrossedwithawhitemale.Whataretheexpectedgenotypicandphenotypicratiosoftheoffspring?
c.Woulditeverbepossibletoproduceamalewithgreyhair?Explain
10.Thechartbelowshowstheinheritanceofhumanbloodtypes.Therearefourdifferentphenotypespossible:A,B,AB,andO.TheallelesAandBarecodominant,andtheOalleleisrecessivetobothAandB.
a.ApersonwithIAIBiscrossedwithapersonwhoisIAIA.Whatarethegenotypicandphenotypicratiosoftheoffspring?
b.ApersonwithtypeABbloodiscrossedwithapersonwithtypeOblood.Whatarethegenotypicandphenotypicratiosoftheoffspring?
DIHYBRIDPUNNETTSQUAREPRACTICEPROBLEMS
ProblemA:Supposethatblack hair (B)isdominantoverblondehair(b) andbrowneyes(E)aredominantover blueeyes(e).
Thefatherhasblackhair(heterozygous)andbrowneyes(heterozygous)andthemotherhasblondehairandblueeyes.
Genotypeoffather–BbEeGenotypeofmother-bbee
1.Whatpercentoftheoffspringwillbetotallyheterozygous?
2.Whatisthephenotyperatio?
3.Whatpercentoftheoffspringwillhaveblondehair andblueeyes?
ProblemB:Usingthesametraitsasabove,crossacompletelyrecessivepersonwithablondehair andhomozygousbrowneyedperson.
- Whatpercentoftheoffspringwillbetotallyheterozygous?
- Whatisthephenotyperatio?
- Whatpercentoftheoffspringwillhaveblondehair andblueeyes?