Mendel & Heredity Review Vocabulary review for Chapter 7 in :Biology: Principles & Explorations Tools A B allele copy of a gene codominance two dominant alleles are expressed at the same time dihybrid cross cross involving 2 pairs of contrasting traits dominant trait that is expressed genetics study of heredity genotype set of alleles that an individual has cross pollination tranfer of pollen from 1 plant to the stigma of another plant genetic disorder harmful effects produced by mutated genes hemoglobin protein in blood hemophilia sex-linked recessive blood clotting disorder heredity transmission of traits from parent to offspring heterozygous individual having different factors for a trait homozygous both factors have the same information incomplete dominance trait displayed is an intermediate of both parents monohybrid cross cross involving 1 pair of contrasting traits law of independent assortment states that pairs of alleles separate independently of each other during gamete formation law of segregation states that members of each pairs of alleles separate when gametes are formed multiple alleles traits that have genes with more than 2 alleles mutation changes in genetic material pedigree a family history phenotype physical appearance P generation parental generation phenylketonuria genetic disorder resulting in the lack of an enzyme that converts phenylalanine to tyrosine probability likelihood a specific event will occur Punnett Square diagram used to predict probable outcome of a cross recessive trait that is masked self pollination process when a plant fertilizes itself sex linked trait trait determined by gene found on the X chromosome sickle cell anemia genetic disorder resulting in defective hemoglobin true breeding ensuring that a trait is pure