AP Bio Genetics- Genotypes?

Question

the genotypes of the F1 offspring are all AaBbCcDd. Assuming independent assortment of all four genes, what are the probabilities that the F2 offspring will be:

a) aabbccdd
b) AaBbCcDd
c) AABBCCDD
d) AaBBccDd
e) AaBBCCdd

i really dont understand the question at all. I'm sure that if someone can show work for one of them, i'll be able to figure out the rest. Please, this is due tomorrow, I've been working on this for a week, and I've already done 30 of them. :(

Answer 1

This of these as four monohybrid crosses happening at the same time. Each cross produces a similar pattern in the Punnett square because the parents are heterozygous for every trait. If we think of Rr x Rr, then the four boxes of the Punnett square will be RR, Rr, rR, rr .... 1 RR: 2 Rr: 1rr.

When you work these problems, the answer will be the product of the probabilities of the individual outcome.

For part a)
Probability of getting aa is 1/4.
Probability of getting bb is 1/4.
Probability of getting cc is 1/4.
Probability of getting dd is 1/4.
Multiply them all together ... 1/4*/1/4*1/4*1/4= 1/256

Look at part d)
Probability of Aa is 1/2
Prob of BB is 1/4
Prob of cc is 1/4
Prob of Dd is 1/2
Multiply together for answer: 1/2*1/4*1/4*1/2=1/64

They're pretty quick when you can picture the Punnett square for each pair of alleles.