[Campbell Biology P.332] In Concept Check 14.3, a cross between a gray rooster and a gray he... | Practice Question

In Concept Check 14.3, a cross between a gray rooster and a gray hen produces 15 gray, 6 black, and 8 white chicks. What is the most likely mode of inheritance for feather color in these chickens?

  • A: Complete dominance
  • B: Incomplete dominance
  • C: Epistasis
  • D: Polygenic inheritance

Explanation

The offspring numbers 15 gray, 6 black, 8 white are approximately in a 2:1:1 ratio Gray:Black:White . This 1:2:1 phenotypic ratio from a cross of two identical heterozygotes is the hallmark of incomplete dominance. The gray chickens are heterozygous e.g., BW , while the black BB and white WW are homozygous.