Final answer:
Mendel's Law of Segregation states that alleles for each trait separate during gamete formation, ensuring each gamete carries only one allele for each trait. The offspring inherits one allele from each parent, resulting in specific phenotypic ratios as observed in Mendel's experiments with pea plants.
Step-by-step explanation:
Mendel's Law of Segregation is a foundational concept in genetics, describing how alleles for a trait separate during the formation of gametes. This law suggests that each parent contributes one unit of genetic material for each trait, and these units, or alleles, segregate during meiosis.
The Law of Segregation ensures that each gamete receives only one allele for each trait, which then pairs with another allele during fertilization, resulting in the offspring having two alleles for each trait.
Mendel observed that true-breeding pea plants with contrasting traits produced an F1 generation expressing the dominant trait, and an F2 generation showing both dominant and recessive traits in a 3:1 phenotypic ratio. This can be demonstrated through Punnett squares, which show how alleles combine from each parent to produce offspring with various combinations of genotypes: homozygous dominant, heterozygous, or homozygous recessive.
The equal segregation of alleles explains why heterozygous individuals can receive one dominant and one recessive allele from either parent. The physical basis of Mendel's Law is the first division of meiosis where homologous chromosomes are separated into different gametes.
At the time of Mendel's research, the meiotic segregation of chromosomes in sexual reproduction was not yet understood by the scientific community, highlighting the groundbreaking nature of Mendel's work.