Which generation is produced directly from crossing two P-generation organisms?

• A. F1 generation
• B. P generation
• C. F2 generation
• D. G1 generation

Answer: (B)

The generation produced directly from crossing two parental, true-breeding organisms is the F1 generation. In classic genetics, the two parents form the P (parental) generation, and their offspring are the first filial generation, abbreviated F1. This naming reflects the idea of offspring arising from the parents: “filial” means relating to offspring, with F1 being the first set produced by the P generation. In Mendel’s experiments, crossing true-breeding lines typically yields offspring that express the dominant trait and are often heterozygous if the parents were homozygous for contrasting alleles. If you cross the F1 individuals among themselves, you get the F2 generation, which shows segregation of alleles. The G1 label isn’t part of this traditional naming scheme.