Forensic Biology and DNA Analysis Practice Exam 2026 – Free Blood, Semen, and Skeletal Remains Practice Questions and Study Guide

Rh-positive status means the D antigen is present on red blood cells. The defining feature of the Rh blood group system is the presence or absence of the D antigen on the surface of RBCs. If the D antigen is present, the individual is considered Rh-positive; if it is absent, the individual is Rh-negative. The other statements are not correct because Rh status is specifically tied to the D antigen, not to its absence in positives, not to independence from D, and not determined by ABO type, which is a separate blood group system. In practice, serology uses anti-D antibodies to detect the D antigen: if the RBCs agglutinate, they’re Rh-positive; if not, Rh-negative.