Homologous chromosomes pair together to form a ______________.. The process of pairing homologous chromosomes is called________.. In each bivalent. there would be a total of ______ centromeres.. In a bivalent, you should be able to see_____ sister chromatids.. A physical exchange of material between two homologus chromosomes is called______.. The visible evidence that exchange of genetic material has occuredis called a ___________.. . the answer choices are:. chiasma. two. one. eight four. bivalent. crossing over. synapsis. centromere. cytokinesis