If a cross is made in a pea plant between round yellow parent with a genotype Rr YY another Round Yellow parent with Rr Yy, what is the phenotypic ratio of resultant offspring?

Parent with RrYY genotype can form the gametes with genotype as RY and rY. Parent with genotype Rr Yy can form gametes with the genotypes as RY, Ry, rY and rY. When random fertilisations take place between these gametes of parents, there is formation of offspring with the genotypes for Round and Yellow are RRYY(1), RrYY (2), RrYy (2) and RRYy (1) – a total of 6 round and yellow. Wrinkled and yellow are two one each of rrYY and rrYy. Hence the ratio is 6 : 1 i.e. 3 : 1.