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NEET 2025, Biology Q4: Mendel's laws of Inheritance

NEET2025Biology
Q.

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 cf the F2 generation?

  1. A

    Phenotypic ratio - 9 : 7

  2. B

    Phenotypic ratio - 1 : 2 : 1

  3. C

    Phenotypic ratio - 3 : 1

  4. D

    Phenotypic ratio - 9 : 3 : 3 : 1

Solution

This is Mendel's classical dihybrid cross. Round (R) is dominant over wrinkled (r), and yellow (Y) is dominant over green (y).

Crossing pure RRYY rryy gives an F1 of RrYy (all round yellow). Selfing F1 with independent assortment produces the F2 phenotypic ratio:

— round yellow : round green : wrinkled yellow : wrinkled green.

Concept behind this question

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