In dogs, length of hair is controlled by a gene with 2 alleles. Short hair is dominant to long hair. Two heterozygous short-haired dogs are crossed and they produce a short-haired puppy. What is the probability that the puppy is heterozygous?
A) 1/2
B) 2/3
C) 1/3
D) 3/4
E) 1/4

Question

Quizplus · Accepted Answer

The cross of two heterozygous short-haired dogs (Ss x Ss) results in a genotypic ratio of 1SS:2Ss:1ss. Since the puppy is short-haired, it can either be SS or Ss. Given this, the probability of the puppy being heterozygous (Ss) out of the short-haired possibilities (SS or Ss) is 2/3.

In Dogs, Length of Hair Is Controlled by a Gene