Exceptions Typically, you can trace and predict the patterns of inheritance by completing a monohybrid or dihybrid cross to see the end result of a cross of one gene or two genes. However, some alleles are neither dominant nor recessive, and many traits are controlled by multiple alleles or multiple genes. These four exceptions to this typical pattern of inheritance must be explained through separate patterns. These four exceptions are incomplete dominance, multiple alleles, codominance, and polygenic traits. In each of the sections below, you will review all four exceptions and complete practice scenarios to answer each question set. Information Flag question Information text Incomplete Dominance In incomplete dominance, the heterozygous phenotype is somewhere between the two homozygous phenotypes. Neither allele is completely dominant or recessive. For example, the gene for red flowers is equally as expressive as white flowers. When the two flowers have offspring, a pink color is made. A red carnation crossed with a white carnation they create a pink carnation. Incomplete dominance is a form of inheritance in which one allele for a specific trait is not completely dominant over the other allele, resulting in an intermediate phenotype. Question 1 Not complete Points out of 1.00 Flag question Question text In Japanese four o'clock plants, the red (R) color is incompletely dominant over white (r) flowers, and the heterozygous condition (Rr) results in plants with pink flowers. For the following, construct a Punnett square and give the genotypic and phenotypic ratios of the offspring. In this scenario, you are crossing a heterozygous plant with a homozygous, dominant red plant. {Hint: The first parent genotype needs to go down the left side of the Punnet square, and the second parent genotype needs to go across the top of the Punnett square.} Genotypic and Phenotypic Ratios for Japanese Four O'clocks
