Some dogs have erect ears; others have drooping ears. Some dogs bark when following scent; others are silent. Erect ears and barking are due to dominant alleles located on different chromosomes. If two dihybrids are crossed, A) the most common phenotype is drooping ears and barking. B) all droopy-eared, silent dogs are pure-breeding. C) the least common phenotype is drooping ears and barking. D) there will be no phenotypes or genotypes that resemble the original parents. E) there will be no offspring that resemble the F ₁ generation.

Question

Quizplus · Accepted Answer

In a dihybrid cross, the least common phenotype is the one with both recessive traits. Droopy ears and silent behavior are recessive, so droopy-eared, silent dogs are homozygous recessive for both traits, making them pure-breeding.

Some Dogs Have Erect Ears; Others Have Drooping Ears