Biology · Oct / Nov 2020 · Paper 12 · Question 37

In a species of mouse, fur colour can be black or white. Two black female mice were allowed to mate with the same black male. One female had nine young, all of which were black. The other female had seven young, five black and two white. One of these white mice was male, and is allowed to mate with a heterozygous female. What is the expected ratio of phenotypes of their offspring?

1. A1 black : 1 white
2. B1 black : 3 white
3. C1 black : 2 grey : 1 white
4. D3 black : 1 white

As printed in the paper