Final answer:
The F1 generation in Mendel's pea plant experiments were the offspring of true-breeding P generation plants and all exhibited the dominant trait. The F2 generation, resulting from F1 self-fertilization, showed a mix of dominant and recessive traits, revealing inheritance patterns.
Step-by-step explanation:
The first filial generation, or F1 generation, in Mendel's experiments with Pea plants (Pisum sativum) resulted from the cross-pollination of the P generation (parental generation) plants that were true-breeding for specific traits. All of the plants in the F1 generation exhibited the dominant trait, such as having violet flowers instead of white, or yellow and round seeds as opposed to green or wrinkled seeds. Through this observation, Mendel postulated the presence of inherited factors (now known as genes) that determine characteristics. When the F1 generation plants self-fertilized, the resulting F2 generation exhibited a mix of the dominant and recessive traits, leading to Mendel's discovery of the principles of inheritance that include the laws of segregation and independent assortment.