Question

PLEASE HELP! I need explanations and I will give out a medal!

In one type of plant, orange petals (O) are dominant over yellow petals (o) and tall stems (T) are dominant over short stems (t). Complete a dihybrid cross for parents with the genotypes: OOTt × OoTt and answer the following in complete sentences.

Answer 1

List the likelihood of each possible offspring genotype.
List the likelihood of each possible offspring phenotype.

Answer 2

@aaronq

Answer 3

you can construct a punnet square and then find the ratios.

Answer 4

Ok here's my attempt at making a Punnett square without pen and paper... Without the full stops yahoo removes the spaces so it doesn't make sense. Just try to imagine it as a grid :)

I've tried editing it but for some reason it really doesn't like all the full stops so it's cut off the last column. The rightmost gamete (i.e. the fourth at the top) should be Ot and the combinations below should be OOTt, OOtt, oOTt and oOtt.


............OT...........Ot.........OT....

OT......OOTT.......OOTt....OOTT.......O...

Ot......OOTt.........OOtt.....OOTt........

oT.....oOTT.......oOTt......oOTT..........

ot.....oOtT.........oOtt......oOtT........

Ok so you have your 8 gametes top and left and your 16 possible combinations in the middle.

For genotypes:
50% OO - homozygous orange. 50% Oo - heterozygous orange.
25% TT - homozygous tall. 50% Tt - heterozygous tall. 25 % tt - homogenous short.

For phenotypes:
100% orange petals, no yellow.
75% tall stems, 25% short stems.

Sorry it's not in complete sentences but I hope that helps !

Just ask if you need clarification.

Answer 5

Hope this helps