Question

a rooster with grey feathers is mated with a hen of the same phenotype. they produce 15 chicks with grey feathers, 7 chicks with black feathers, and 8 chicks with white feathers. what is the simplest explanation for this inheritance pattern? (aks 7e1)
a the trait is dominant, which produces grey even when the black and white alleles are present.
b the trait is recessive, which produces black or white when the grey allele is not present.
c the trait is codominant, which produces grey when black and white are crossed.
d the trait is incompletely dominant, which produces grey when black and white are crossed.

Explanation:

To determine the inheritance pattern, we analyze each option:

• Option A: If grey were dominant, we wouldn't expect roughly equal numbers of black, white, and grey offspring from two grey parents (since dominant traits would mask others more).
• Option B: A recessive trait would only appear when both alleles are recessive, but here grey parents produce black, white, and grey, so recessive doesn't fit.
• Option C: Codominance means both traits are expressed simultaneously (e.g., speckled), but here grey is a blend, not a mix of black and white.
• Option D: Incomplete dominance occurs when the heterozygous phenotype is an intermediate (blend) of the two homozygous phenotypes. The grey rooster and hen (intermediate) producing grey, black, and white chicks fits incomplete dominance, as black (homozygous) and white (homozygous) can be crossed to produce grey (heterozygous, intermediate).

Answer:

D. The trait is incompletely dominant, which produces grey when black and white are crossed.