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 long eyelashes; half are solid tails and short eyelashes) B. 9:3:3:1 ratio (9 polka-dot tails and short eyelashes, 3 polka-dot tails and long eyelashes, 3 solid tails and short eyelashes, 1 solid tail and long eyelash) C. 9:3:3:1 ratio (9 polka-dot tails and long eyelashes, 3 polka-dot tails and short eyelashes, 3 solid tails and long eyelashes, 1 solid tail and short eyelash) D. 1:1 ratio (half are polka-dot tails and short eyelashes; half are solid tails and long eyelashes)

Answer 1

Making a Punnet square for this, will make it easier to get the right answer. First take into consideration the genotype of each parent. It says that both individuals are heterozygous for both traits. So each of them have a gentoype of PpLl. Using the foil method, we can come up with the Punnet square:

PL Pl pL pl
PL PPLL PPLl PpLL PpLl
Pl PPLl PPll PpLl PPll
pL PpLL PpLl ppLL ppLl
pl PpLl Ppll ppLl ppll

Now the possible phenotypic combinations would be:
Polka dot tail, Long eyelashes: PpLl or PPLL
Polka dot tail, short eyelashes: Ppll or PPll
Solid color tail, Long eyelashes: ppLl or ppLL
Solid color tail, short eyelashes: ppll

Next step is to count how many times their genotype comes out in the Punnet square.

The first combination occurs 9 times.
The second combination occurs 3 times.
The third combination occurs 3 times.
The fourth combination occurs 1 time.

The ratio is the 9:3:3:1 (9 polka dot long, long; 3 polka-dot, short, 3 solid, long; 1 solid, short)

The answer is letter C.