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. 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) C. 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) D. 1:1 ratio (half are polka-dot tails and long eyelashes; half are solid tails and short eyelashes)

Answer 1

The genotype of heterozygous would be PpLl.

Formed gametes are PP  Pl  pL  pl

Parents: PpLl  x PpLl

 

The correct answer is B. 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)

 

Polka-dot tails and long eyelashes: PPLL PPLl PpLL PpLl PPLl PpLl PpLL PpLl PpLl

Polka-dot tails and short eyelashes: PPll Ppll Ppll

Solid tails and long eyelashes: ppLL ppLl pp Ll

Solid tail and short eyelash: ppll