NEET · Biology · STD 12 - 4. principal of inheritance and variation

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?

A Phenotypic ratio-1:2:1
B Phenotypic ratio-3:1
C Phenotypic ratio- \(9: 3: 3: 1\)
D Phenotypic ratio-9:7

Verified Solution

Answer & Solution

Correct Answer

(C) Phenotypic ratio- \(9: 3: 3: 1\)

Step-by-step Solution

Detailed explanation

A classical dihybrid cross performed by Mendel involves.
A cross which was made between a pure round yellow seeded pea plant (RRYY) with wrinkled green seeded plant (rryy). Yellow colour is dominant over green and round seed shape over wrinkled seed shape.
Phenotypic ratio in F2 generation

Apply the relevant identity from the chapter and substitute the values established in the previous step, keeping the original constraint in view.

Use the simplified expression to isolate the unknown, then plug the result back into the question setup to confirm the working is internally consistent.

Cross-check against a boundary or limiting case. Both the dimensional balance and the qualitative behaviour at the extreme should agree with the candidate answer.

Combine the steps above to identify the correct option. The remaining choices each fail at least one of the consistency, dimensional, or boundary checks.

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