Final answer:
Exposure of an XY-containing zygote to a chemical mutagen like EMS can result in Hemophilia A due to a mutation in a gene responsible for producing Factor VIII protein.
Step-by-step explanation:
Detailed Answer:
A chemical mutagen such as ethylmethane sulfonate (EMS) can introduce single-base substitutions in DNA. If an XY-containing zygote (fertilized egg) is exposed to EMS, it can lead to a mutation in a gene responsible for producing Factor VIII protein, which is involved in blood clotting. This mutation can result in Hemophilia A, a genetic disorder characterized by decreased or absent Factor VIII protein.