A female purebred white cat and a male purebred black cat had a litter of 12 kittens. Out of the 12 kittens, all but 3 were black. How many female kittens were there?
Answer
9
x= recessive: white
X= dominant: black
A purebred, female, white cat would have the alleles xx for fur colour (white). A purebred, male, black cat would have the alleles YX (black).
The possible allele combinations for offspring are as follows (set up a Punnett Square)
Xx……Yx
Xx……Yx
Every female kitten would be black, with a recessive allele for white fur. Every male kitten would be white. There are 9 black kittens, so that means there are 9 female kittens.