What are the phenotypes for the parents and possible phenotypes for the offspring?1) BB and Bb2) BB and bb3) Rr and Rr4) rr and rr

Expert Answers
pacorz eNotes educator| Certified Educator

I can help you with the genotypes here, but not with the phenotypes, because you did not supply enough information. To discuss phenotypes, which tell how the gene is expressed in the individual, we need to know what genes we are dealing with; in other words, what the letters B and R stand for in this question.

For BB x Bb, half the offspring will be BB and half will be Bb. They will all look alike, as do their parents, because, assuming B is dominant over b (and not codominant or incomplete), every individual has t least one B, and that is what will be expressed in the phenotype.

For BB x bb, all the offspring will be Bb. They will all look like the BB parent, although they carry a hidden recessive gene.

For Rr x Rr, one fourth of the offspring will be RR, half will be Rr, and one fourth will be rr. Thus three fourths will look like the parents, and the remaining one fourth will look different, expressing the recessive trait. Here's the Punnet square for the cross:

For rr x rr, all offspring will be rr and all will look like the parents.