Dominant and recessive traits Transitional Reasoning Download PDF

Questions

1. 1.

   A researcher studying coat texture in a rodent population crosses two rough-coated parents and observes that approximately 25% of their offspring have smooth coats, while the remaining 75% have rough coats. When two smooth-coated individuals from this lineage are subsequently mated together, all of their offspring across multiple litters exclusively produce smooth coats. Based on these experimental results, which conclusion correctly describes the relationship between these alleles and the genotypes of the original parents?

   • A) The smooth-coat allele is dominant, and both original parents are homozygous recessive for the trait.
   • B) The trait shows incomplete dominance, meaning both original parents must possess two identical dominant alleles.
   • C) The rough-coat allele is dominant to the smooth-coat allele, and both original parents are heterozygous.
   • D) The rough and smooth alleles are co-dominant, causing the smooth-coated offspring to represent a homozygous dominant genotype.