Step 1: Understand what a dihybrid cross is. It involves two traits, each with two alleles.
Step 2: Identify the traits you are crossing. For example, let's say we are looking at flower color (purple vs. white) and plant height (tall vs. short).
Step 3: Determine the genotypes of the parents. For example, one parent could be homozygous for both traits (PPHH) and the other could be homozygous for the opposite traits (pphh).
Step 4: Use a Punnett square to visualize the possible combinations of alleles from both parents.
Step 5: Count the different phenotypes that result from the combinations in the Punnett square.
Step 6: Calculate the ratio of each phenotype. You will typically find 9 of one phenotype, 3 of another, 3 of a third, and 1 of the last, leading to a 9:3:3:1 ratio.
