A male mouse with a grey coat is mated with an albino female. Their six offspring all have grey fur. The albino female is then mated with a second grey male mouse. Four of the seven offspring in this litter are albino. 1.What are the probable genotypes of the three-parent mice? (4)

2. A male from the first litter is mated with a grey female from the second litter. What is the expected ratio of phenotypes among the offspring? (3)