dihybrid cross destroyer bio

[BRZ24]

---

Members don't see this ad.

question:
A dihybrid cross was done between tall round peas. Tall is dominant to short and round is dominant to wrinkled. What fraction of the offspring will be short and wrinkled?



How the hell are we supposed to figure out the genotype of the parents and do the cross?

if I make
T= tall
t= short
R=round
r=wrinkled

there are two possibilities of genotypes that each parent can have that is tall and round
TtRr
TTRR

wtf???

 

[dent4]

When dealing with a heterozygous dihybrid cross, the phenotypic ratio will more than likely ALWAYS be in a 9:3:3:1 ratio.
9/16- tall, round
3/16- tall, wrinkled
3/16- short, round
1/16- short, wrinkled ANSWER

No need to waste time and draw out the dihybrid cross.

 

[BRZ24]

When dealing with a heterozygous dihybrid cross, the phenotypic ratio will more than likely ALWAYS be in a 9:3:3:1 ratio.
9/16- tall, round
3/16- tall, wrinkled
3/16- short, round
1/16- short, wrinkled ANSWER

No need to waste time and draw out the dihybrid cross.

How do you know if the parents are heterozygous?

I can have both of them to be heterozygous and homozygous and still be tall and round

 

[Dgeorg6]

No where in the question does it state it is heterozygous or not?? If not you just have to assume that they are both heterozygous b\c thats the only way you could get a offspring that is recessive for both traits (unless of course one of the answer choices is 0).

 

[BRZ24]

No where in the question does it state it is heterozygous or not?? If not you just have to assume that they are both heterozygous b\c thats the only way you could get a offspring that is recessive for both traits (unless of course one of the answer choices is 0).

Yep you are right. Wasn't thinking about that

thanks.

 

[dent4]

Sorry forget to reply back, but yes that's exactly why bc if either were to be homozygous you wouldn't receive the homozygous recessive phenotype in the F1 generation.