Question

a rooster with grey feathers is mated with a hen of the same phenotype. they produce 15 chicks with grey feather is the simplest explanation for this inheritance pattern? (aks 7e1)
a the trait is recessive, which produces black or white when the grey allele is not present.
b the trait is codominant, which produces grey when black and white are crossed.
c the trait is dominant, which produces grey even when the black and white alleles are present.
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 (recessive): Recessive traits are hidden unless two recessive alleles are present. But here, grey is produced when black and white alleles are present, so not recessive.
• Option B (codominant): Codominance means both traits are expressed simultaneously (e.g., black and white patches), but the problem says grey is produced, not a mix of black and white. Eliminate B.
• Option C (dominant): A dominant trait would mask the other, but grey is produced only when both black and white alleles are present, not when one is dominant. Eliminate C.
• Option D (incompletely dominant): In incomplete dominance, a heterozygous genotype produces a phenotype intermediate between the two homozygous phenotypes. Here, black (homozygous) + white (homozygous) = grey (intermediate), which matches incomplete dominance.

Answer:

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