Question

Dogs can be yellow, brown or black. The color is decided by two genes: one gene (F) governs hair color (black dominant over brown) while another gene (P) allows placement of color onto the fur. Yellow labs are homozygous recessive for color placement. mate a yellow dog who is homozygous recessive for both traits with a black dog who is heterozygous for both traits and describe their babies.

can someone help me figure out how to set up a punnett square for this?

Answer 1

This is called a dihybrid cross because the trait (dog color) is determined by two different alleles F and P which sort independently.

You're told that the yellow dog is homozygous for both recessive traits so it's a ppff. The dog you cross it with is heterozygous for both traits, so it's PpFf. You put those on either axis of your Punnett Square and go for it.

Clear?

Answer 2

hi, if one of the offspring was Ffpp, would it be yellow, brown or black?

Answer 3

Yellow. Whether or not it has the possibility of being brown/black depends on whether it has at least one dominant P allele. This one doesn't, so it's yellow regardless of whether it is F/f, F/F or f/f.

Answer 4

so if the offspring were:
FfPp
Ffpp
ffPp
ffpp
then would 50% of them be yellow, 25% black and 25% brown?

Answer 5

Yes, at least I think so.

Answer 6

you've helped me a ton :) I'd give you another medal if I could!