Dihybrid Cross in Pea Plants
A dihybrid cross involves the study of two different traits or characteristics in an organism. In this case, we are examining the round and yellow seed trait (RRYY) and the wrinkled and green seed trait (rryy) in pea plants.

Parental Genotypes
The two parents in this cross have the genotypes RRYY and rryy. The capital letters represent the dominant alleles for each trait, while the lowercase letters represent the recessive alleles. The first parent has both dominant alleles, resulting in round and yellow seeds. The second parent has both recessive alleles, leading to wrinkled and green seeds.

F1 Generation
When these two parents are crossed, the resulting offspring in the F1 generation will all be heterozygous for both traits. The genotype of all the F1 offspring will be RrYy, with round and yellow seeds.

F2 Generation Phenotypes
To determine the phenotypic ratio in the F2 generation, we need to consider the possible combinations of alleles that can arise from the F1 generation.

Possible Gametes from F1 Generation
The F1 generation individuals can produce four different types of gametes due to the independent assortment of alleles during meiosis. The possible gametes are: RY, Ry, rY, and ry.

Crossing the F1 Generation
When the F1 generation individuals are crossed, their gametes can combine in various ways. Let's examine all the possible combinations:

- RY x RY: This cross will produce offspring with round and yellow seeds (RRYY).
- RY x Ry: This cross will produce offspring with round and yellow seeds (RRYy).
- RY x rY: This cross will produce offspring with round and green seeds (RRyy).
- RY x ry: This cross will produce offspring with round and green seeds (RRyy).
- Ry x RY: This cross will produce offspring with round and yellow seeds (RRYy).
- Ry x Ry: This cross will produce offspring with round and yellow seeds (RrYy).
- Ry x rY: This cross will produce offspring with round and green seeds (Rryy).
- Ry x ry: This cross will produce offspring with round and green seeds (Rryy).
- rY x RY: This cross will produce offspring with round and green seeds (RRyy).
- rY x Ry: This cross will produce offspring with round and green seeds (Rryy).
- rY x rY: This cross will produce offspring with wrinkled and yellow seeds (rrYy).
- rY x ry: This cross will produce offspring with wrinkled and green seeds (rryy).
- ry x RY: This cross will produce offspring with round and green seeds (RRyy).
- ry x Ry: This cross will produce offspring with round and green seeds (Rryy).
- ry x rY: This cross will produce offspring with wrinkled and green seeds (rryy).
- ry x ry: This cross will produce offspring with wrinkled and green seeds (rryy).

Phenotypic Ratio in F2 Generation
Now, let's count the number of offspring with each phenotype:

Round and yellow seeds (RRYY): 1
Round and yellow seeds (RRYy): 2
Round and green seeds (RRyy): 2
Round and green seeds (