A six-year-old Caucasian boy was seen by a maxillofacial surgeon to be evaluated for surgical repair of severe jaw misalignment. The boy was deemed an appropriate candidate for surgery at this time, with a second surgery planned during his teen years to complete the correction. The boy was adopted, and no family history was available. He had no personal history of excessive bleeding or bruising. The pre-surgical CBC results including platelet count were within reference ranges. Pre-surgical hemostasis testing is as follows: Ryan L. Reference RangePT 10.5 9-12 secondsAPTT 40 32-46 secondsBleeding time 7 1-9 minutesRequired:Describe the principle and reagents for the PT and APTT.