Genetics! pls help! thank you very much?

in snapdragons, if red-flowered plants are pollinated by white-flowered plants, the offspring have pink flowers. Draw a Punnett swuare to show (a)result of crossing red-flowered and white-flowered plants and (b)then allowing their offspring to self-pollinate. what are the phenotype ratios in each case?





pls help.. i don't understand this question...


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Genetics! pls help! thank you very much?
Assume there is one gene for flower color:


R is the red allele


r is the white allele





RR is red


Rr is pink


rr is white





Crossing red(RR) and white(rr) flowers


.....R......R


r...Rr.....Rr


r...Rr.....Rr





All pink flowers


--------------------------------------...


The cross of two pink (Rr) flowers:


.....R.......r


R..RR...Rr


r...Rr.....rr





This gives a red:pink:white ratio of 1:2:1.
Reply:thanks for answering my question.. im sorry i wasn't able to pick a best answer coz i didn't have much time to decide.. but i was able to read your answer and use it... thanks a lot! Report It

Reply:It's an example of incomplete dominance (if you don't know that already, look it up and study some more).





R=Red


r=White





For this phenotypic ratio, I am using RR:Rr:rr, because it is incomplete dominance, as opposed to RR and Rr:rr, with a regular example





r r


R Rr Rr





R Rr Rr





It says that that all of this generation, known as F1(F for Filial), that all of the offspring will be pink, the phenotypic ration is 0:4:0





When allowed to self-pollinate, this Punnett square occurs,





R r


R RR Rr





r Rr rr





In this generation, known as F2, the phenotypic ratio is 1:2:1.