Atrait exhibits 100% concordance for both monozygotic and dizygotic twins. what conclusion can you draw about the role of genetic factors in determining differences in the trait? a. genetic factors are extremely important. b. genetic factors are somewhat important. c. genetic factors are unimportant. d. both genetic and environmental factors are important.

During crossing-over, a. genetic material is exchanged between nonsister chromatids, resulting in new combinations of alleles. b. nonsister chromatids from each homologous chromosome of a tetrad are exchanged, resulting in new combinations of alleles. c. one homologous chromosome of a tetrad is exchanged with another tetrad, resulting in new combinations of alleles. d. sister chromatids from each homologous chromosome of a tetrad are exchanged, resulting in new combinations of alleles. e. genetic material is exchanged between sister chromatids, resulting in new combinations of alleles.