In cats, the allele for long hair is recessive to the allele for short hair (so short hair is dominant). if two cats that are heterozygous for hair length (aa x aa) have offspring, what percentage of the offspring will have long hair.

25%,1:3 This is due to the heterozygous condition to produce on homozygous long and one homozygous short then two heterozygous short. ie 1:2:1, but short is dominant and heterozygous short ate taken to be short, thus modifying the ratio to 1:3,1:3 is 25%:75%. therefore homozygous long is 25%.