Final answer:
A Punnett square for the P generation cross between purple smooth (PPSS) and yellow rough (ppss) pea plants results in an F1 generation of all heterozygous purple smooth (PpSs) offspring. The Punnett square for an F1 generation cross of PpSs x PpSs would show a dihybrid cross, resulting in a variety of genotypic combinations in the F2 generation.
Step-by-step explanation:
To answer your question regarding the creation of Punnett squares for crosses involving pea plants with purple smooth and yellow rough traits, we must use the principles of Mendelian genetics.
For the P generation cross (purple smooth - PPSS x yellow rough - ppss), the offspring in the F1 generation would all be heterozygous for both traits (PpSs), showing the dominant phenotypes, purple and smooth. This is because both traits are inherited in a simple dominant-recessive pattern, so the dominant allele P (purple) suppresses the expression of the recessive allele p (yellow), and the dominant allele S (smooth) does the same to the recessive allele s (rough).
For the F1 generation cross (PpSs x PpSs), we are looking at a dihybrid cross. Each parent can produce four types of gametes (PS, Ps, pS, and ps), and we align these along the top and left side of the Punnett square. There are 16 possible combinations, and each box represents the genotype of the potential offspring. To visualize the full Punnett square and the resulting genotypic ratios, you would draw a 4x4 grid and fill in the combinations accordingly. The phenotypic ratio for the F2 generation can then be determined based on the dominance relationship of the alleles.