The Colour of Wheat Seeds Is Controlled by Two Genes

Multiple Choice

The colour of wheat seeds is controlled by two genes. The alleles (R₁ and r₁) of one gene assort independently to the alleles (R₂ and r₂) of the other gene. R₁ and R₂ produce a red pigment while r₁ and r₂ do not produce any pigment. The effect of the alleles is additive so that R₁/R₁; R₂/R₂ give dark red colour while r₁/r₁; r₂/r₂ produces white. A plant with R₁/r₁; R₂/r₂ has intermediate red colour. A plant heterozygous at both gene loci was allowed to self-fertilise. What proportion of offspring would be expected to have a colour similar to the parent?

A) 0
B) 1/4
C) 3/4
D) 3/8
E) 1/2