Final answer:
In Mendelian genetics, true-breeding P generation parents are crossed to produce the F1 generation, which are heterozygous and display the dominant phenotype. A Punnett square can predict the genotypes of the F2 generation when F1 self-fertilizes.
Step-by-step explanation:
In Mendelian genetics, the P generation (parental generation) refers to the original true-breeding parents in a breeding experiment. True-breeding means that the parents are homozygous for a certain trait; for instance, they possess either two dominant or two recessive alleles for that particular trait. An example is crossing pea plants that are true-breeding for the dominant yellow seed phenotype with plants that have the recessive green seed phenotype. As a result of this cross, all offspring in the F1 generation (first filial generation) are heterozygous for the trait, meaning that they have one dominant and one recessive allele, thus exhibiting the dominant phenotype due to dominant allele expression.
To predict the genotypes of the subsequent F2 generation (second filial generation), one could employ a Punnett square analysis. This involves allowing the F1 generation plants to self-fertilize, producing the F2 generation, which typically shows a phenotypic ratio of dominant to recessive traits following Mendel's laws of inheritance.