Understanding Mendel's F2 Generation
Mendel's experiments with pea plants laid the foundation for genetics. In his studies, he observed the inheritance of single traits, such as flower color or seed shape.
Key Concepts of Mendelian Inheritance
- Parental Generation (P): Mendel began with true-breeding plants (homozygous) for a specific trait, like purple and white flowers.
- First Filial Generation (F1): The offspring from the P generation were all heterozygous (one allele from each parent), displaying the dominant trait. For instance, all F1 plants had purple flowers.
Phenotypic Ratio in F2 Generation
- Self-Pollination of F1: When F1 plants are self-pollinated, they produce the second filial generation (F2).
- Genotypic Breakdown: The F2 generation consists of the following genotypes:
- 1 homozygous dominant (PP)
- 2 heterozygous (Pp)
- 1 homozygous recessive (pp)
- Phenotypic Ratio: The phenotypes observed in the F2 generation are:
- 3 plants with the dominant trait (purple flowers)
- 1 plant with the recessive trait (white flowers)
Thus, the phenotypic ratio is 3:1, which indicates that for every 4 plants, 3 will display the dominant phenotype, and 1 will display the recessive phenotype.
Conclusion
This 3:1 ratio is a fundamental principle of inheritance, demonstrating how traits are passed from one generation to the next, confirming Mendel's laws of segregation and dominance. Thus, the correct answer to the question about the phenotypic ratio in Mendel's F2 generation for a single trait is indeed option 'B' - 3:1.