Final answer:
Mendel's law of segregation explains that genes that control characteristics separate and go to different gametes, leading to the 3:1 ratio observed in the F2 generation of pea plants. The law is based on meiosis, where homologous chromosomes segregate into daughter nuclei, although this wasn't understood in Mendel's era.
Step-by-step explanation:
Understanding Mendel's Law of Segregation
The law of segregation is Mendel's first law stating that the two factors, or genes, controlling a characteristic segregate or separate into different gametes. Observations by Mendel of true-breeding pea plants led to findings in which the F1 generation expressed the dominant trait, while the F2 generation showed both dominant and recessive traits in a 3:1 ratio. This discovery was made possible by the equal segregation of alleles, which is demonstrated through the use of Punnett squares to predict offspring outcomes. The law of segregation is rooted in meiosis' first division, where homologous chromosomes and their respective genes are divided into different gametes, leading to an equal likelihood of offspring inheriting one allele or the other.
The physical basis of the law is found in meiosis, particularly the separation of homologous chromosomes into daughter nuclei, ensuring that each gamete carries a single allele for each gene. This biological process was not understood in Mendel's time but is recognized today as the mechanism underpinning the law of segregation.