Question

How to do Dihybrid Cross on a punnett square???

Answer 1

Do you know what a punnett square is?

Answer 2

Step 1: Determine the parental genotypes from the text above, the word "heteroyzous" is the most important clue, and you would also need to understand that self fertilized means you just cross it with itself.
Step 2: Determine the gametes. This might feel a little like the FOIL method you learned in math class. Combine the R's and Ys of each parent to represent sperm and egg. Do this for both parents
Step 3: Set up a large 4x4 Punnet square, place one gamete set from the parent on the top, and the other on the side
Step 4: Write the genotypes of the offspring in each box and determine how many of each phenotype you have.