Final answer:
The P generation in genetics stands for the parental generation and comprises the organisms initially crossed in a breeding experiment. In Mendel's experiments with pea plants, this involved crossing true-breeding plants with dominant yellow seeds with those having recessive green seeds.
Step-by-step explanation:
In genetics, the P generation, short for parental generation, refers to the original group of organisms being crossed in a breeding experiment. For example, in Mendel's classic pea plant experiments, he crossed pea plants that were true-breeding for dominant yellow seeds (phenotype) with plants that were true-breeding for recessive green seeds. The result of this cross produced the F1 (first filial) generation of heterozygotes, which exhibited the yellow seed phenotype due to the dominance of the yellow trait. Punnett squares are often utilized to predict the possible genotypes and phenotypes of the subsequent F2 generation that comes from allowing the F1 generation to self-pollinate.
The analysis of these crosses and generation patterns was foundational for Mendel to propose his laws of inheritance. He observed not only the P and F1 generations but continued to study the characteristics of the F2, F3, and further generations, deducing the basic principles of heredity. The observations from the P generation through to these subsequent generations allowed Mendel to formulate his postulates, which became the cornerstone of modern genetics.