Explain Mendel's law of independent assortment with the help of a dihybrid cross. Show the phenotypic and genotypic ratios obtained in the F2 generation.

Q: Explain Mendel's law of independent assortment with the help of a dihybrid cross. Show the phenotypic and genotypic ratios obtained in the F2 generation.

Introduction to the Law of Independent Assortment\nMendel's Law of Independent Assortment states that when two pairs of traits are combined in a hybrid, segregation of one pair of characters is independent of the other pair of characters. In other words, alleles of two (or more) different genes get sorted into gametes independently of one another. The allele a gamete receives for one gene does not influence the allele received for another gene. Explanation through Dihybrid Cross\nA dihybrid cross involves the inheritance of two different pairs of contrasting characteristics simultaneously. Mendel crossed pure breeding pea plants with round yellow seeds (RRYY) with wrinkled green seeds (rryy). Parent Generation (P): Round Yellow (RRYY) × Wrinkled Green (rryy) Gametes from P: RY and ry F1 Generation: All offspring had the genotype RrYy and showed the phenotype round yellow seeds, demonstrating the dominance of round and yellow traits over wrinkled and green traits. Selfing of F1 Generation\nWhen F1 plants (RrYy) were self-pollinated, the gametes produced by each parent were of four types in equal proportions: RY, Ry, rY, and ry. Punnett Square Analysis\nA 16-square Punnett square is used to combine these four types of gametes from male and female parents. The combinations result in four distinct phenotypes in the F2 generation: Round Yellow: 9 plants Round Green: 3 plants Wrinkled Yellow: 3 plants Wrinkled Green: 1 plant F2 Generation Ratios Phenotypic Ratio: 9 : 3 : 3 : 1 (Round Yellow : Round Green : Wrinkled Yellow : Wrinkled Green) Genotypic Ratio: A complex 1 : 2 : 1 : 2 : 4 : 2 : 1 : 2 : 1 ratio representing various homozygous and heterozygous combinations. Conclusion\nThis clearly demonstrates that the genes for seed shape (round/wrinkled) and seed color (yellow/green) inherited independently of each other, proving the Law of Independent Assortment.

Question

Accepted Answer

Introduction to the Law of Independent Assortment
Mendel's Law of Independent Assortment states that when two pairs of traits are combined in a hybrid, segregation of one pair of characters is independent of the other pair of characters. In other words, alleles of two (or more) different genes get sorted into gametes independently of one another. The allele a gamete receives for one gene does not influence the allele received for another gene. Explanation through Dihybrid Cross
A dihybrid cross involves the inheritance of two different pairs of contrasting characteristics simultaneously. Mendel crossed pure breeding pea plants with round yellow seeds (RRYY) with wrinkled green seeds (rryy). Parent Generation (P): Round Yellow (RRYY) × Wrinkled Green (rryy) Gametes from P: RY and ry F1 Generation: All offspring had the genotype RrYy and showed the phenotype round yellow seeds, demonstrating the dominance of round and yellow traits over wrinkled and green traits. Selfing of F1 Generation
When F1 plants (RrYy) were self-pollinated, the gametes produced by each parent were of four types in equal proportions: RY, Ry, rY, and ry. Punnett Square Analysis
A 16-square Punnett square is used to combine these four types of gametes from male and female parents. The combinations result in four distinct phenotypes in the F2 generation: Round Yellow: 9 plants Round Green: 3 plants Wrinkled Yellow: 3 plants Wrinkled Green: 1 plant F2 Generation Ratios Phenotypic Ratio: 9 : 3 : 3 : 1 (Round Yellow : Round Green : Wrinkled Yellow : Wrinkled Green) Genotypic Ratio: A complex 1 : 2 : 1 : 2 : 4 : 2 : 1 : 2 : 1 ratio representing various homozygous and heterozygous combinations. Conclusion
This clearly demonstrates that the genes for seed shape (round/wrinkled) and seed color (yellow/green) inherited independently of each other, proving the Law of Independent Assortment.

CBSE · Class 10 · Science · HeredityExplain Mendel's law of independent assortment with the help of a dihybrid cross. Show the phenotypic and genotypic ratios obtained in the F2 generation.

Explanation through Dihybrid Cross\nA dihybrid cross involves the inheritance of two different pairs of contrasting characteristics simultaneously. Mendel crossed pure breeding pea plants with round yellow seeds (RRYY) with wrinkled green seeds (rryy).

Selfing of F1 Generation\nWhen F1 plants (RrYy) were self-pollinated, the gametes produced by each parent were of four types in equal proportions: RY, Ry, rY, and ry.

Punnett Square Analysis\nA 16-square Punnett square is used to combine these four types of gametes from male and female parents. The combinations result in four distinct phenotypes in the F2 generation:

F2 Generation Ratios

Conclusion\nThis clearly demonstrates that the genes for seed shape (round/wrinkled) and seed color (yellow/green) inherited independently of each other, proving the Law of Independent Assortment.