This 9:3:3:1 phenotypic ratio is the classic Mendelian ratio for a dihybrid cross in which the alleles of two different genes assort independently into gametes. Figure 1: A classic Mendelian example of independent assortment: the 9:3:3:1 phenotypic ratio associated with a dihybrid cross (BbEe × BbEe).
How do you write a phenotypic ratio?
Write the amount of homozygous dominant (AA) and heterozygous (Aa) squares as one phenotypic group. Count the amount of homozygous recessive (aa) squares as another group. Write the result as a ratio of the two groups. A count of 3 from one group and 1 from the other would give a ratio of 3:1.
What would a 9 3 3 1 ratio of phenotypes in offspring of a dihybrid cross indicate?
If both parents are heterogeneous for both traits the ratio of phenotypes is the ratio of 9:3:3:1. One trait is dominant and the other trait is recessive. Of the 16 possible offsprings only 1 will have both recessive genes. Only with double recessives will the phenotype show both recessives.
What is dihybrid cross explain with example?
In a dihybrid cross, Mendel took a pair of contradicting traits together for crossing; for example color and the shape of seeds at a time. … While the wrinkled shape and green color of seeds are recessive traits. Then, F1 progeny was self-pollinated. This resulted in four different combinations of seeds in F2 generation.
What is phenotype example?
Examples of phenotypes include height, wing length, and hair color. Phenotypes also include observable characteristics that can be measured in the laboratory, such as levels of hormones or blood cells.