Final answer:
When two parents with round seeds are crossed, the offspring will mostly have round seeds due to the dominance of the round seed trait (R) over the wrinkled seed trait (r). If both parents are heterozygous, the offspring will have a 3:1 ratio of round to wrinkled seeds as per Mendelian genetics.
Step-by-step explanation:
When two parents with round seeds are crossed, we can predict the phenotype of the offspring using the principles of Mendelian genetics. Round seeds (R) are dominant to wrinkled seeds (r), as discovered by Gregor Mendel through his experiments with pea plants. If both parents contribute a dominant allele for round seeds, then the offspring will also have round seeds, since they only need one dominant allele to express the trait.
In one of Mendel's experiments, when true-breeding parents with round seeds and wrinkled seeds were crossed, the F₁ offspring all exhibited round seeds because they possessed at least one dominant allele for the trait (Rr). When these F₁ plants were self-pollinated to produce the F₂ generation, the offspring exhibited round and wrinkled seeds in a typical 3:1 Mendelian ratio, with approximately 75% having round seeds and about 25% having wrinkled seeds. Therefore, if both parents have round seeds, it is likely that the majority of the F₂ offspring will have round seeds unless both parents were heterozygous, in which case the Punnett square would predict a 3:1 ratio of round to wrinkled seeds in the offspring.