1. How could you find out whether blue eyes or brown eyes is dominant? 1. My thoughts: Would you just cross a blue-eyed individual and a brown-eyed indivdual and observe what's prevalent in their offspring? 2. Gary has 6 fingers on each hand & 6 toes on each foot. His wife Sandy and daughter Stephanie are normal. Extra digits is a dominant trait. What fraction of their children would be expected to have extra digits? My thougts: Let's say R= dominant allele, r= recessive allele. Since Gary has extra digits, I know his genotype is rr, but how do I do if the mother is RR or Rr? 3. Phenylketonuria (PKU) is a genetic defect harming the brain. A normal couple have a baby with PKU. What is the probability that their next child will be affected? What is the probability that if they have 2 more children, neither will be affected?