In guinea pigs, brown coat color allele (B) is dominant over red (b), and the solid color allele (S) is dominant over the spotted (s). The F1 offspring of a cross between true-breeding brown, solid-colored guinea pigs and red, spotted pigs are crossed. What proportion of their offspring (F2) would be expected to be red and solid colored?

Explanation:

As given;

Brown coat color (B) is dominant over (b), so B is dominant over b.

Solid color (S) is dominant over the spotted(s), so S is dominant over s.

crossing between true breeding brown, solid colored guinea pig( BBSS) with red spotted pig( bbss)

so parents are  BBSS× bbss

gametes are, of parent-1; BS, and parent-2: bs

F1 is : BbSs,

cross between F1 and F1

F2 is : BBSS, BBSs, BbSS, BbSsBBssBbssbbSSbbss etc

So red and solid color offspring are (bbS_) = 3/16

the sphincter muscles at the end of the digestive tract is the anus.