Question

Suppose that a dominant allele (P) codes for a polka-dot tail and a recessive allele (p) codes for a solid colored tail. In addition, suppose that a dominant allele (L) codes for long eyelashes and a recessive allele (l) codes for short eyelashes. If two individuals heterozygous for both traits (tail color and eyelash length) mate, what's the probability of the phenotypic combinations of the offspring? A. 1:1 ratio (half are polka-dot tails and short eyelashes; half are solid tails and long eyelashes) B. 1:1 ratio (half are polka-dot tails and long eyelashes; half are solid tails and short eyelashes) C. 9:3:3:1 ratio (9 polka-dot tails and long eyelashes, 3 polka-dot tails and short eyelashes, 3 solid tails and short eyelashes, 1 solid tail and short eyelash) D. 9:3:3:1 ratio (9 polka-dot tails and short eyelashes, 3 polka-dot tails and short eyelashes, 3 solid tails and long eyelashes, 1 solid tail and long eyelash)

Answer 1

If two individual are heterozygous for both traits then there genotype will each look like this PpLl. To find the probability, you need to do a cross with both traits. Each parent has the possibility of giving the following combinations: PL, Pl, pL, pl.
 
                 PL        Pl         pL           pl
PL         PPLL     PPLl     PpLL        PpLl        
Pl          PPLl      PPll      PpLl          Ppll
pL         PpLL     PpLl      ppLL        ppLl
pl          PpLl      Ppll       ppLl          ppll

Polka dot tail/ long lashes: 9/16
Polka dot tail/ short lashes: 3/16
Solid Tail / long lashes: 3/16
solid tail/ short lashes 1/16

The answer is (C) 9:3:3:1 ratio with 9 polka dot tails and long eyelashes, 3 polka dot tails and short eyelashes, 3 solid tails and long eyelashes (there seems to be a typo in the question) and 1 short tail short eyelash