Two new pure-breeding strains of mouse (strain 1 and strain 2)have been obtained.Crosses between strain 1 and wild type,as well as crosses between strain 2 and wild type and between strain 1 and strain 2 always produce 100% wild-type mice. What kind(s)of interactions can be deduced from these results?

Question

Quizplus · Accepted Answer

The fact that crosses between strain 1 and strain 2 always produce 100% wild-type mice indicates that the two strains complement each other - meaning that they have mutations in different genes that together result in a wild-type phenotype. The fact that crosses between each strain and wild type also produce 100% wild-type mice suggests that the mutations in both strains are recessive and therefore show dominance when paired with wild type. Therefore, both complementation and dominance can be deduced from these results, making choice D the best option. Epistasis is not necessarily indicated by these results as there is no evidence of one gene masking the expression of another.

Two New Pure-Breeding Strains of Mouse (Strain 1 and Strain