In mice, coat colour is controlled by a single gene with two alleles:
- Y Y\,Y is the dominant allele for a yellow coat.
- y y\,y is the recessive allele for a grey coat.
The homozygous dominant genotype (YYYYYY) is lethal, causing the death of the embryo early in development.
Two yellow mice are crossed. The Punnett square below shows the outcomes of this cross:
What percentage of the surviving offspring are expected to have a yellow coat?
33%33\%33%
50%50\%50%
67%67\%67%
75%75\%75%