Question

5. 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 long 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 long eyelashes, 3 solid tails and short eyelashes, 1 solid tail and long eyelash)

Answer 1

Answer:

C.

Explanation:

According to your problem, you have to two traits to be crossed, tail and eyelashes:

P - polka-dot tail                L - long eyelashes

p - solid colored tail           l - short eyelashes

It says we cross two individuals that are HETEROzygous for both traits, this means that their genotypes have each allele for each trait. So the cross would be:

PpLl x PpLl

Attached is a Punnet for this cross and ratio count for both genotype and phenotype.

The ratio based on phenotype would be the following:

9 polka-long: 3 polka-short: 3 solid-long: 1 solid-short