Genes R and Y follow independent assortment. If RRYY produce round yellow seeds and rryy produce wrinkled green seeds, what will be the phenotypic ratio of the F2 generation?  

The correct answer is Phenotypic ratio - 9 : 3 : 3 : 1

Concept:

Mendel proposed some laws to explain his understanding of inheritance. Today, these are called the Principles or Laws of Inheritance.

1. ​Law of Dominance -  It is used to explain the expression of only the dominant character in a monohybrid cross in the F1 generation and the expression of both dominant and recessive in the F2 generation.
2. Law of segregation -  ​It states that the alleles do not show any blending. During gamete formation, the alleles segregate and pass equally and both the characters are recovered as such in the F2 generation.
3. Law of Independent Assortment - It states that during gamete formation, one pair of traits segregates from another pair of traits independently.

Explanation:

In pea plants:

• The round seed (R) is dominant over the wrinkled seed (r)
• The yellow color (Y) seed is dominant over the green color seed (y)

The cross is in the following,

F1:                                                  RrYy (Round and yellow)

Selfing of F1:     RrYy (Round and yellow)   X   RrYy (Round and yellow)

Gametes:                          RY, Ry, rY, ry      X     RY, Ry, rY, ry

The phenotypic ratio produced is 9: 3: 3: 1.

• 9 - Round yellow
• 3 - Round green
• 3 - Wrinkled yellow
• 1 - Wrinkled green

Therefore, in F2 generation two new combination of seeds Round yellow and wrinkled green seeds would be produced that differ from the parent type.