Final answer:
Mendel's Law of Segregation states that an organism has two alleles for each trait, which separate and go to different gametes during the formation of sex cells, leading to genetic variation in the offspring. This law explains the predictable 3:1 trait ratio seen in Mendel's pea plant experiments.
Step-by-step explanation:
Mendel's Law of Segregation is a foundational principle in genetics and a crucial part of understanding how inheritance works. According to this law, an organism possesses two alleles for any particular trait, and these alleles segregate from one another during the formation of gametes.
More specifically, every individual has two units for each trait, one inherited from each parent. During gamete formation, each gamete receives only one of the two alleles. Upon fertilization, offspring receive a combination of alleles from both parents, restoring the two-allele state.
This segregation of alleles accounts for the genetic variation seen in the offspring.
Through his experiments with pea plants, Mendel discovered that the F₂ generations expressed the dominant and recessive traits in a predictable 3:1 ratio. Mendel's observations support the equal segregation of alleles, which allows geneticists to use tools such as the Punnett square to predict the distribution of inherited traits.
The physical basis of this law is meiosis, the division of sex cells where homologous chromosomes separate and distribute genetic information to daughter cells.