Using a punnet square and an explanation describe if a square-eyed pet mates with another square-eyed pet can they have any round-eyed offspring?

Yes, they can have round-seeded offspring if they are both heterozygous for the square-eyed trait.

Explanation:

The question here involves a gene that codes for eye shape in a pet. Let's assume the square-eyed allele (S) is dominant over the round-eyed allele (s). This means that the S allele will mask the phenotypic expression of s in a heterozygous state (Ss).

Hence, in a heterozygous state (Ss), a square-eyed phenotype will still be produced. However, according to the question, the only way a round-eyed offspring will result from a cross between two square-eyed parents is if they are both heterozygous for the square-eyed trait (Ss).

Therefore, in a cross between a Ss and Ss pet (see punnet square in attached image), which are both square-eyed, four possible offsprings will result with genotypes: SS, Ss Ss, ss

SS and Ss genotypes are both phenotypically square-eyed while ss will be phenotypically round-eyed, since it is a recessive trait and can only be expressed in a homozygous recessive condition.

Thus, following this explanation, 1/4 of the offsprings will be round-eyed if the parents are both heterozygous for square-eyed trait.