<P> In fertilization and breeding experiments (and especially when discussing Mendel's laws) the parents are referred to as the "P" generation and the offspring as the "F1" (first filial) generation . When the F1 offspring mate with each other, the offspring are called the "F2" (second filial) generation . One of the common diagrams used to predict the result of cross-breeding is the Punnett square . </P> <P> When studying human genetic diseases, geneticists often use pedigree charts to represent the inheritance of traits . These charts map the inheritance of a trait in a family tree . </P> <P> Organisms have thousands of genes, and in sexually reproducing organisms these genes generally assort independently of each other . This means that the inheritance of an allele for yellow or green pea color is unrelated to the inheritance of alleles for white or purple flowers . This phenomenon, known as "Mendel's second law" or the "law of independent assortment," means that the alleles of different genes get shuffled between parents to form offspring with many different combinations . (Some genes do not assort independently, demonstrating genetic linkage, a topic discussed later in this article .) </P> <P> Often different genes can interact in a way that influences the same trait . In the Blue - eyed Mary (Omphalodes verna), for example, there exists a gene with alleles that determine the color of flowers: blue or magenta . Another gene, however, controls whether the flowers have color at all or are white . When a plant has two copies of this white allele, its flowers are white--regardless of whether the first gene has blue or magenta alleles . This interaction between genes is called epistasis, with the second gene epistatic to the first . </P>

What is the difference between biology and genetics