Britannica Sources used in this answer

Why did short pea plants reappear in the second generation of Mendel’s experiments?

Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

Four kittens with different fur patterns-three tabby and one black-and-white-lying together in a box, illustrating genetic variation among offspring. — heredity Each offspring is a combination of its two parents, receiving some dominant traits from its mother and others from its father.

Short pea plants reappeared in the second generation ( $F_{2}$ ) of Gregor Mendel’s experiments because the trait for shortness is recessive, while tallness is dominant.12

In the first generation ( $F_{1}$ ), all hybrid plants were tall because they inherited one allele for tallness ( $T$ ) and one for shortness ( $t$ ). Although the plants were phenotypically tall, they carried the recessive gene for shortness. According to Mendel’s law of segregation, these alleles separate during the formation of gametes.23

When these $F_{1}$ hybrids were self-pollinated, the random union of gametes resulted in an $F_{2}$ generation where some offspring inherited two recessive alleles ( $t t$ ). These individuals expressed the short trait, which had been masked in the previous generation. This process resulted in a characteristic 3:1 ratio of dominant to recessive traits.341