explain why when mendel allowed the F1 generation of all tea plants reappeared in the F1 generation.
This phenomenon, known as the reemergence of the parental traits in the F1 generation, can be explained by Mendel's principle of dominance. According to this principle, one allele (or variant) of a gene may be dominant over another, which is recessive. In Mendel's experiments with pea plants, he discovered that when a dominant allele is present, it will always be expressed while the recessive allele will only be expressed if it is present in both copies.
In the case of Mendel's experiments with pea plants, the F1 generation inherited one dominant allele from one parent and one recessive allele from the other parent. Since the dominant allele is always expressed, the dominant trait was visible in the F1 generation. However, the recessive allele was still present in the genetic makeup of the F1 plants, even though it was not visibly expressed.
When these F1 plants were allowed to self-pollinate, the recessive allele had the opportunity to be passed on to the next generation. As a result, some of the offspring in the F2 generation inherited two recessive alleles and expressed the recessive trait, leading to the reappearance of the parental traits in the F2 generation. This reemergence of the parental traits demonstrated that the recessive allele was still present in the genetic makeup of the F1 plants, even though it was not expressed in the previous generation.